diff --git a/examples/compiled/airport_connections.vg.json b/examples/compiled/airport_connections.vg.json
index 5556a08675..173bc55892 100644
--- a/examples/compiled/airport_connections.vg.json
+++ b/examples/compiled/airport_connections.vg.json
@@ -145,7 +145,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "org_tuple_fields", "value": [{"type": "E", "field": "origin"}]},
+    {
+      "name": "org_tuple_fields",
+      "value": [{"type": "E", "field": "origin", "index": 0}]
+    },
     {
       "name": "org_toggle",
       "value": false,
diff --git a/examples/compiled/bar_count_minimap.vg.json b/examples/compiled/bar_count_minimap.vg.json
index 0169e05242..3131bbeee5 100644
--- a/examples/compiled/bar_count_minimap.vg.json
+++ b/examples/compiled/bar_count_minimap.vg.json
@@ -219,7 +219,7 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Name", "channel": "y", "type": "E"}]
+          "value": [{"field": "Name", "channel": "y", "type": "E", "index": 0}]
         },
         {
           "name": "brush_translate_anchor",
diff --git a/examples/compiled/brush_table.vg.json b/examples/compiled/brush_table.vg.json
index 0d4c1b8797..b66f4b587d 100644
--- a/examples/compiled/brush_table.vg.json
+++ b/examples/compiled/brush_table.vg.json
@@ -236,8 +236,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/circle_bubble_health_income.vg.json b/examples/compiled/circle_bubble_health_income.vg.json
index f86e8ca66c..a5681faea5 100644
--- a/examples/compiled/circle_bubble_health_income.vg.json
+++ b/examples/compiled/circle_bubble_health_income.vg.json
@@ -69,8 +69,8 @@
     {
       "name": "view_tuple_fields",
       "value": [
-        {"field": "income", "channel": "x", "type": "R"},
-        {"field": "health", "channel": "y", "type": "R"}
+        {"field": "income", "channel": "x", "type": "R", "index": 0},
+        {"field": "health", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/concat_bar_layer_circle.vg.json b/examples/compiled/concat_bar_layer_circle.vg.json
index 13d86385e5..7403ff6121 100644
--- a/examples/compiled/concat_bar_layer_circle.vg.json
+++ b/examples/compiled/concat_bar_layer_circle.vg.json
@@ -292,7 +292,9 @@
         },
         {
           "name": "pts_tuple_fields",
-          "value": [{"field": "Major Genre", "channel": "x", "type": "E"}]
+          "value": [
+            {"field": "Major Genre", "channel": "x", "type": "E", "index": 0}
+          ]
         },
         {
           "name": "pts_toggle",
diff --git a/examples/compiled/concat_hover.vg.json b/examples/compiled/concat_hover.vg.json
index cc80790be5..a7c466ca1a 100644
--- a/examples/compiled/concat_hover.vg.json
+++ b/examples/compiled/concat_hover.vg.json
@@ -5,7 +5,13 @@
   "padding": 5,
   "height": 200,
   "data": [
-    {"name": "hover_store"},
+    {
+      "name": "hover_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -76,7 +82,7 @@
         },
         {
           "name": "hover_tuple_fields",
-          "value": [{"type": "E", "field": "_vgsid_"}]
+          "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
         },
         {
           "name": "hover_toggle",
@@ -115,7 +121,7 @@
               "fill": {"value": "transparent"},
               "stroke": [
                 {
-                  "test": "length(data(\"hover_store\")) && vlSelectionTest(\"hover_store\", datum)",
+                  "test": "length(data(\"hover_store\")) && vlSelectionIdTest(\"hover_store\", datum)",
                   "scale": "color",
                   "field": "Cylinders"
                 },
@@ -208,7 +214,7 @@
         },
         {
           "name": "hover_tuple_fields",
-          "value": [{"type": "E", "field": "_vgsid_"}]
+          "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
         },
         {
           "name": "hover_toggle",
@@ -247,7 +253,7 @@
               "fill": {"value": "transparent"},
               "stroke": [
                 {
-                  "test": "length(data(\"hover_store\")) && vlSelectionTest(\"hover_store\", datum)",
+                  "test": "length(data(\"hover_store\")) && vlSelectionIdTest(\"hover_store\", datum)",
                   "scale": "color",
                   "field": "Cylinders"
                 },
diff --git a/examples/compiled/concat_hover_filter.vg.json b/examples/compiled/concat_hover_filter.vg.json
index a3991765ab..5fe2a83c14 100644
--- a/examples/compiled/concat_hover_filter.vg.json
+++ b/examples/compiled/concat_hover_filter.vg.json
@@ -5,7 +5,13 @@
   "padding": 5,
   "height": 200,
   "data": [
-    {"name": "hover_store"},
+    {
+      "name": "hover_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -28,7 +34,7 @@
       "transform": [
         {
           "type": "filter",
-          "expr": "length(data(\"hover_store\")) && vlSelectionTest(\"hover_store\", datum)"
+          "expr": "length(data(\"hover_store\")) && vlSelectionIdTest(\"hover_store\", datum)"
         }
       ]
     },
@@ -106,7 +112,7 @@
         },
         {
           "name": "hover_tuple_fields",
-          "value": [{"type": "E", "field": "_vgsid_"}]
+          "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
         },
         {
           "name": "hover_toggle",
@@ -251,7 +257,7 @@
         },
         {
           "name": "hover_tuple_fields",
-          "value": [{"type": "E", "field": "_vgsid_"}]
+          "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
         },
         {
           "name": "hover_toggle",
diff --git a/examples/compiled/interactive_area_brush.vg.json b/examples/compiled/interactive_area_brush.vg.json
index 49c36df21f..c8476d1d13 100644
--- a/examples/compiled/interactive_area_brush.vg.json
+++ b/examples/compiled/interactive_area_brush.vg.json
@@ -143,7 +143,9 @@
     },
     {
       "name": "brush_tuple_fields",
-      "value": [{"field": "yearmonth_date", "channel": "x", "type": "R"}]
+      "value": [
+        {"field": "yearmonth_date", "channel": "x", "type": "R", "index": 0}
+      ]
     },
     {
       "name": "brush_translate_anchor",
diff --git a/examples/compiled/interactive_bar_select_highlight.vg.json b/examples/compiled/interactive_bar_select_highlight.vg.json
index 341082f21d..3db1118746 100644
--- a/examples/compiled/interactive_bar_select_highlight.vg.json
+++ b/examples/compiled/interactive_bar_select_highlight.vg.json
@@ -6,8 +6,20 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "highlight_store"},
-    {"name": "select_store"},
+    {
+      "name": "highlight_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
+    {
+      "name": "select_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "values": [
@@ -76,7 +88,7 @@
     },
     {
       "name": "highlight_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "highlight_toggle",
@@ -111,7 +123,7 @@
     },
     {
       "name": "select_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "select_toggle",
@@ -148,18 +160,18 @@
           "cursor": {"value": "pointer"},
           "fillOpacity": [
             {
-              "test": "!length(data(\"select_store\")) || vlSelectionTest(\"select_store\", datum)",
+              "test": "!length(data(\"select_store\")) || vlSelectionIdTest(\"select_store\", datum)",
               "value": 1
             },
             {"value": 0.3}
           ],
           "strokeWidth": [
             {
-              "test": "length(data(\"select_store\")) && vlSelectionTest(\"select_store\", datum)",
+              "test": "length(data(\"select_store\")) && vlSelectionIdTest(\"select_store\", datum)",
               "value": 2
             },
             {
-              "test": "length(data(\"highlight_store\")) && vlSelectionTest(\"highlight_store\", datum)",
+              "test": "length(data(\"highlight_store\")) && vlSelectionIdTest(\"highlight_store\", datum)",
               "value": 1
             },
             {"value": 0}
diff --git a/examples/compiled/interactive_bin_extent.vg.json b/examples/compiled/interactive_bin_extent.vg.json
index 592ef9dc23..b1e13d7a03 100644
--- a/examples/compiled/interactive_bin_extent.vg.json
+++ b/examples/compiled/interactive_bin_extent.vg.json
@@ -194,7 +194,7 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "time", "channel": "x", "type": "R"}]
+          "value": [{"field": "time", "channel": "x", "type": "R", "index": 0}]
         },
         {
           "name": "brush_translate_anchor",
diff --git a/examples/compiled/interactive_bin_extent_bottom.vg.json b/examples/compiled/interactive_bin_extent_bottom.vg.json
index 5b7970e88e..b111c53dcc 100644
--- a/examples/compiled/interactive_bin_extent_bottom.vg.json
+++ b/examples/compiled/interactive_bin_extent_bottom.vg.json
@@ -283,7 +283,7 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "time", "channel": "x", "type": "R"}]
+          "value": [{"field": "time", "channel": "x", "type": "R", "index": 0}]
         },
         {
           "name": "brush_translate_anchor",
diff --git a/examples/compiled/interactive_brush.vg.json b/examples/compiled/interactive_brush.vg.json
index 14ada8c39e..546613c6cd 100644
--- a/examples/compiled/interactive_brush.vg.json
+++ b/examples/compiled/interactive_brush.vg.json
@@ -13,8 +13,13 @@
         {
           "unit": "",
           "fields": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ],
           "values": [[55, 160], [13, 37]]
         }
@@ -187,8 +192,8 @@
     {
       "name": "brush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/interactive_concat_layer.vg.json b/examples/compiled/interactive_concat_layer.vg.json
index 22ecd986c2..d5841fdff8 100644
--- a/examples/compiled/interactive_concat_layer.vg.json
+++ b/examples/compiled/interactive_concat_layer.vg.json
@@ -306,7 +306,9 @@
         },
         {
           "name": "pts_tuple_fields",
-          "value": [{"field": "Major Genre", "channel": "x", "type": "E"}]
+          "value": [
+            {"field": "Major Genre", "channel": "x", "type": "E", "index": 0}
+          ]
         },
         {
           "name": "pts_toggle",
diff --git a/examples/compiled/interactive_dashboard_europe_pop.vg.json b/examples/compiled/interactive_dashboard_europe_pop.vg.json
index 4383308390..7359ce5bf0 100644
--- a/examples/compiled/interactive_dashboard_europe_pop.vg.json
+++ b/examples/compiled/interactive_dashboard_europe_pop.vg.json
@@ -471,7 +471,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Country", "channel": "y", "type": "E"}]
+          "value": [
+            {"field": "Country", "channel": "y", "type": "E", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -795,7 +797,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Country", "channel": "y", "type": "E"}]
+          "value": [
+            {"field": "Country", "channel": "y", "type": "E", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -1189,12 +1193,14 @@
             {
               "field": "Population_ages_65_and_above_of_total",
               "channel": "x",
-              "type": "R"
+              "type": "R",
+              "index": 0
             },
             {
               "field": "Population_ages_15_64_of_total",
               "channel": "y",
-              "type": "R"
+              "type": "R",
+              "index": 1
             }
           ]
         },
diff --git a/examples/compiled/interactive_global_development.vg.json b/examples/compiled/interactive_global_development.vg.json
index 048e8b026c..388a17c697 100644
--- a/examples/compiled/interactive_global_development.vg.json
+++ b/examples/compiled/interactive_global_development.vg.json
@@ -12,7 +12,7 @@
       "values": [
         {
           "unit": "layer_1_layer_1",
-          "fields": [{"type": "E", "field": "year"}],
+          "fields": [{"type": "E", "field": "year", "index": 0}],
           "values": [1955]
         }
       ]
@@ -141,7 +141,10 @@
       "name": "year_tuple",
       "update": "year_year !== null ? {fields: year_tuple_fields, values: [year_year]} : null"
     },
-    {"name": "year_tuple_fields", "value": [{"type": "E", "field": "year"}]},
+    {
+      "name": "year_tuple_fields",
+      "value": [{"type": "E", "field": "year", "index": 0}]
+    },
     {
       "name": "year_modify",
       "on": [
@@ -164,7 +167,7 @@
     },
     {
       "name": "hovered_tuple_fields",
-      "value": [{"type": "E", "field": "country"}]
+      "value": [{"type": "E", "field": "country", "index": 0}]
     },
     {
       "name": "hovered_modify",
@@ -188,7 +191,7 @@
     },
     {
       "name": "clicked_tuple_fields",
-      "value": [{"type": "E", "field": "country"}]
+      "value": [{"type": "E", "field": "country", "index": 0}]
     },
     {
       "name": "clicked_toggle",
diff --git a/examples/compiled/interactive_index_chart.png b/examples/compiled/interactive_index_chart.png
index 6d1c694a00..d3a7c2db8c 100644
Binary files a/examples/compiled/interactive_index_chart.png and b/examples/compiled/interactive_index_chart.png differ
diff --git a/examples/compiled/interactive_index_chart.vg.json b/examples/compiled/interactive_index_chart.vg.json
index 94b5914f0d..cd63190e9a 100644
--- a/examples/compiled/interactive_index_chart.vg.json
+++ b/examples/compiled/interactive_index_chart.vg.json
@@ -11,7 +11,9 @@
       "values": [
         {
           "unit": "layer_0",
-          "fields": [{"field": "date", "channel": "x", "type": "E"}],
+          "fields": [
+            {"field": "date", "channel": "x", "type": "E", "index": 0}
+          ],
           "values": [1104566400000]
         }
       ]
@@ -127,7 +129,7 @@
     },
     {
       "name": "index_tuple_fields",
-      "value": [{"field": "date", "channel": "x", "type": "E"}]
+      "value": [{"field": "date", "channel": "x", "type": "E", "index": 0}]
     },
     {
       "name": "index_toggle",
diff --git a/examples/compiled/interactive_layered_crossfilter.vg.json b/examples/compiled/interactive_layered_crossfilter.vg.json
index b2d5350c4e..d776499204 100644
--- a/examples/compiled/interactive_layered_crossfilter.vg.json
+++ b/examples/compiled/interactive_layered_crossfilter.vg.json
@@ -288,7 +288,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "distance", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "distance", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -663,7 +665,7 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "delay", "channel": "x", "type": "R"}]
+          "value": [{"field": "delay", "channel": "x", "type": "R", "index": 0}]
         },
         {
           "name": "brush_translate_anchor",
@@ -1038,7 +1040,7 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "time", "channel": "x", "type": "R"}]
+          "value": [{"field": "time", "channel": "x", "type": "R", "index": 0}]
         },
         {
           "name": "brush_translate_anchor",
diff --git a/examples/compiled/interactive_layered_crossfilter_discrete.vg.json b/examples/compiled/interactive_layered_crossfilter_discrete.vg.json
index 4ce170285d..5622bd4683 100644
--- a/examples/compiled/interactive_layered_crossfilter_discrete.vg.json
+++ b/examples/compiled/interactive_layered_crossfilter_discrete.vg.json
@@ -224,7 +224,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "distance", "channel": "x", "type": "R-RE"}]
+          "value": [
+            {"field": "distance", "channel": "x", "type": "R-RE", "index": 0}
+          ]
         },
         {
           "name": "brush_toggle",
@@ -393,7 +395,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "delay", "channel": "x", "type": "R-RE"}]
+          "value": [
+            {"field": "delay", "channel": "x", "type": "R-RE", "index": 0}
+          ]
         },
         {
           "name": "brush_toggle",
@@ -562,7 +566,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "time", "channel": "x", "type": "R-RE"}]
+          "value": [
+            {"field": "time", "channel": "x", "type": "R-RE", "index": 0}
+          ]
         },
         {
           "name": "brush_toggle",
diff --git a/examples/compiled/interactive_legend.vg.json b/examples/compiled/interactive_legend.vg.json
index 5e1c0ccd2e..810cd401b8 100644
--- a/examples/compiled/interactive_legend.vg.json
+++ b/examples/compiled/interactive_legend.vg.json
@@ -94,7 +94,7 @@
     },
     {
       "name": "industry_tuple_fields",
-      "value": [{"type": "E", "field": "series"}]
+      "value": [{"type": "E", "field": "series", "index": 0}]
     },
     {
       "name": "industry_toggle",
diff --git a/examples/compiled/interactive_legend_dblclick.vg.json b/examples/compiled/interactive_legend_dblclick.vg.json
index f76010964b..057780441b 100644
--- a/examples/compiled/interactive_legend_dblclick.vg.json
+++ b/examples/compiled/interactive_legend_dblclick.vg.json
@@ -94,7 +94,7 @@
     },
     {
       "name": "industry_tuple_fields",
-      "value": [{"type": "E", "field": "series"}]
+      "value": [{"type": "E", "field": "series", "index": 0}]
     },
     {
       "name": "industry_toggle",
diff --git a/examples/compiled/interactive_line_brush_cursor.vg.json b/examples/compiled/interactive_line_brush_cursor.vg.json
index d49201148c..ab21f06e4e 100644
--- a/examples/compiled/interactive_line_brush_cursor.vg.json
+++ b/examples/compiled/interactive_line_brush_cursor.vg.json
@@ -108,7 +108,7 @@
     },
     {
       "name": "brush_tuple_fields",
-      "value": [{"field": "date", "channel": "x", "type": "R"}]
+      "value": [{"field": "date", "channel": "x", "type": "R", "index": 0}]
     },
     {
       "name": "brush_translate_anchor",
diff --git a/examples/compiled/interactive_line_hover.vg.json b/examples/compiled/interactive_line_hover.vg.json
index 3639c09689..a3cca6bc8b 100644
--- a/examples/compiled/interactive_line_hover.vg.json
+++ b/examples/compiled/interactive_line_hover.vg.json
@@ -12,7 +12,7 @@
       "values": [
         {
           "unit": "layer_0",
-          "fields": [{"type": "E", "field": "symbol"}],
+          "fields": [{"type": "E", "field": "symbol", "index": 0}],
           "values": ["AAPL"]
         }
       ]
@@ -64,7 +64,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "hover_tuple_fields", "value": [{"type": "E", "field": "symbol"}]},
+    {
+      "name": "hover_tuple_fields",
+      "value": [{"type": "E", "field": "symbol", "index": 0}]
+    },
     {
       "name": "hover_toggle",
       "value": false,
diff --git a/examples/compiled/interactive_multi_line_label.vg.json b/examples/compiled/interactive_multi_line_label.vg.json
index 3e5f7bea26..976b053716 100644
--- a/examples/compiled/interactive_multi_line_label.vg.json
+++ b/examples/compiled/interactive_multi_line_label.vg.json
@@ -91,7 +91,7 @@
     },
     {
       "name": "label_tuple_fields",
-      "value": [{"field": "date", "channel": "x", "type": "E"}]
+      "value": [{"field": "date", "channel": "x", "type": "E", "index": 0}]
     },
     {
       "name": "label_toggle",
diff --git a/examples/compiled/interactive_multi_line_pivot_tooltip.vg.json b/examples/compiled/interactive_multi_line_pivot_tooltip.vg.json
index a46e52142c..1c8f32ae76 100644
--- a/examples/compiled/interactive_multi_line_pivot_tooltip.vg.json
+++ b/examples/compiled/interactive_multi_line_pivot_tooltip.vg.json
@@ -73,7 +73,10 @@
         {"events": [{"source": "view", "type": "mouseout"}], "update": "null"}
       ]
     },
-    {"name": "hover_tuple_fields", "value": [{"type": "E", "field": "date"}]},
+    {
+      "name": "hover_tuple_fields",
+      "value": [{"type": "E", "field": "date", "index": 0}]
+    },
     {
       "name": "hover_toggle",
       "value": false,
diff --git a/examples/compiled/interactive_multi_line_tooltip.vg.json b/examples/compiled/interactive_multi_line_tooltip.vg.json
index 9ae455cc63..15c53d2ac1 100644
--- a/examples/compiled/interactive_multi_line_tooltip.vg.json
+++ b/examples/compiled/interactive_multi_line_tooltip.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "hover_store"},
+    {
+      "name": "hover_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/seattle-weather.csv",
@@ -57,7 +63,7 @@
     },
     {
       "name": "hover_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "hover_toggle",
@@ -139,7 +145,7 @@
         "update": {
           "stroke": [
             {
-              "test": "length(data(\"hover_store\")) && vlSelectionTest(\"hover_store\", datum)",
+              "test": "length(data(\"hover_store\")) && vlSelectionIdTest(\"hover_store\", datum)",
               "value": "black"
             },
             {"value": "transparent"}
diff --git a/examples/compiled/interactive_overview_detail.vg.json b/examples/compiled/interactive_overview_detail.vg.json
index e429262af7..7e80765bd9 100644
--- a/examples/compiled/interactive_overview_detail.vg.json
+++ b/examples/compiled/interactive_overview_detail.vg.json
@@ -248,7 +248,7 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "date", "channel": "x", "type": "R"}]
+          "value": [{"field": "date", "channel": "x", "type": "R", "index": 0}]
         },
         {
           "name": "brush_translate_anchor",
diff --git a/examples/compiled/interactive_paintbrush.vg.json b/examples/compiled/interactive_paintbrush.vg.json
index d66ffbba69..84b87c7b83 100644
--- a/examples/compiled/interactive_paintbrush.vg.json
+++ b/examples/compiled/interactive_paintbrush.vg.json
@@ -7,7 +7,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -48,7 +54,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -93,7 +99,7 @@
           "y": {"scale": "y", "field": "Miles_per_Gallon"},
           "size": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "value": 300
             },
             {"value": 50}
diff --git a/examples/compiled/interactive_paintbrush_color.vg.json b/examples/compiled/interactive_paintbrush_color.vg.json
index 913a4f1e07..5c23d91842 100644
--- a/examples/compiled/interactive_paintbrush_color.vg.json
+++ b/examples/compiled/interactive_paintbrush_color.vg.json
@@ -7,7 +7,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -46,7 +52,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -81,7 +87,7 @@
           "opacity": {"value": 0.7},
           "fill": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
diff --git a/examples/compiled/interactive_paintbrush_color_nearest.vg.json b/examples/compiled/interactive_paintbrush_color_nearest.vg.json
index db0b103e36..a0c2738656 100644
--- a/examples/compiled/interactive_paintbrush_color_nearest.vg.json
+++ b/examples/compiled/interactive_paintbrush_color_nearest.vg.json
@@ -7,7 +7,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -48,7 +54,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -85,7 +91,7 @@
           "opacity": {"value": 0.7},
           "fill": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
diff --git a/examples/compiled/interactive_paintbrush_interval.vg.json b/examples/compiled/interactive_paintbrush_interval.vg.json
index a7bc7dbf2a..76396388f0 100644
--- a/examples/compiled/interactive_paintbrush_interval.vg.json
+++ b/examples/compiled/interactive_paintbrush_interval.vg.json
@@ -174,8 +174,8 @@
     {
       "name": "paintbrush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/interactive_paintbrush_simple_false.vg.json b/examples/compiled/interactive_paintbrush_simple_false.vg.json
index 7a89c340b8..525ce83e68 100644
--- a/examples/compiled/interactive_paintbrush_simple_false.vg.json
+++ b/examples/compiled/interactive_paintbrush_simple_false.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -46,7 +52,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -92,7 +98,7 @@
           "y": {"scale": "y", "field": "Miles_per_Gallon"},
           "size": [
             {
-              "test": "length(data(\"paintbrush_store\")) && vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "length(data(\"paintbrush_store\")) && vlSelectionIdTest(\"paintbrush_store\", datum)",
               "value": 300
             },
             {"value": 50}
diff --git a/examples/compiled/interactive_paintbrush_simple_true.vg.json b/examples/compiled/interactive_paintbrush_simple_true.vg.json
index f039fd7d29..95055f218b 100644
--- a/examples/compiled/interactive_paintbrush_simple_true.vg.json
+++ b/examples/compiled/interactive_paintbrush_simple_true.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -46,7 +52,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -92,7 +98,7 @@
           "y": {"scale": "y", "field": "Miles_per_Gallon"},
           "size": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "value": 300
             },
             {"value": 50}
diff --git a/examples/compiled/interactive_panzoom_splom.vg.json b/examples/compiled/interactive_panzoom_splom.vg.json
index b4d3aaaa81..4183d65cff 100644
--- a/examples/compiled/interactive_panzoom_splom.vg.json
+++ b/examples/compiled/interactive_panzoom_splom.vg.json
@@ -177,8 +177,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -379,8 +384,8 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -562,7 +567,9 @@
         },
         {
           "name": "grid_tuple_fields",
-          "value": [{"field": "Horsepower", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "grid_translate_anchor",
@@ -764,8 +771,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -947,7 +959,9 @@
         },
         {
           "name": "grid_tuple_fields",
-          "value": [{"field": "Acceleration", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "grid_translate_anchor",
@@ -1147,8 +1161,8 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -1330,7 +1344,14 @@
         },
         {
           "name": "grid_tuple_fields",
-          "value": [{"field": "Miles_per_Gallon", "channel": "x", "type": "R"}]
+          "value": [
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            }
+          ]
         },
         {
           "name": "grid_translate_anchor",
@@ -1532,8 +1553,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
@@ -1736,8 +1762,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/interactive_panzoom_vconcat_shared.vg.json b/examples/compiled/interactive_panzoom_vconcat_shared.vg.json
index 1b0b71ce9e..07f6c9d60a 100644
--- a/examples/compiled/interactive_panzoom_vconcat_shared.vg.json
+++ b/examples/compiled/interactive_panzoom_vconcat_shared.vg.json
@@ -106,8 +106,13 @@
         {
           "name": "region_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/interactive_point_init.vg.json b/examples/compiled/interactive_point_init.vg.json
index 9a8f1b4b4e..f4b3baa254 100644
--- a/examples/compiled/interactive_point_init.vg.json
+++ b/examples/compiled/interactive_point_init.vg.json
@@ -12,16 +12,16 @@
         {
           "unit": "",
           "fields": [
-            {"type": "E", "field": "Cylinders"},
-            {"type": "E", "field": "Year"}
+            {"type": "E", "field": "Cylinders", "index": 0},
+            {"type": "E", "field": "Year", "index": 1}
           ],
           "values": [4, 1981]
         },
         {
           "unit": "",
           "fields": [
-            {"type": "E", "field": "Cylinders"},
-            {"type": "E", "field": "Year"}
+            {"type": "E", "field": "Cylinders", "index": 0},
+            {"type": "E", "field": "Year", "index": 1}
           ],
           "values": [8, 1972]
         }
@@ -66,8 +66,8 @@
     {
       "name": "CylYr_tuple_fields",
       "value": [
-        {"type": "E", "field": "Cylinders"},
-        {"type": "E", "field": "Year"}
+        {"type": "E", "field": "Cylinders", "index": 0},
+        {"type": "E", "field": "Year", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/interactive_query_widgets.vg.json b/examples/compiled/interactive_query_widgets.vg.json
index 545c77863f..26c05a8494 100644
--- a/examples/compiled/interactive_query_widgets.vg.json
+++ b/examples/compiled/interactive_query_widgets.vg.json
@@ -13,8 +13,8 @@
         {
           "unit": "layer_0",
           "fields": [
-            {"type": "E", "field": "Cylinders"},
-            {"type": "E", "field": "Year"}
+            {"type": "E", "field": "Cylinders", "index": 0},
+            {"type": "E", "field": "Year", "index": 1}
           ],
           "values": [4, 1977]
         }
@@ -82,8 +82,8 @@
     {
       "name": "CylYr_tuple_fields",
       "value": [
-        {"type": "E", "field": "Cylinders"},
-        {"type": "E", "field": "Year"}
+        {"type": "E", "field": "Cylinders", "index": 0},
+        {"type": "E", "field": "Year", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/interactive_seattle_weather.vg.json b/examples/compiled/interactive_seattle_weather.vg.json
index 4ae517a563..e4d19fa057 100644
--- a/examples/compiled/interactive_seattle_weather.vg.json
+++ b/examples/compiled/interactive_seattle_weather.vg.json
@@ -172,7 +172,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "monthdate_date", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "monthdate_date", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -448,7 +450,9 @@
         },
         {
           "name": "click_tuple_fields",
-          "value": [{"field": "weather", "channel": "color", "type": "E"}]
+          "value": [
+            {"field": "weather", "channel": "color", "type": "E", "index": 0}
+          ]
         },
         {
           "name": "click_toggle",
diff --git a/examples/compiled/interactive_splom.vg.json b/examples/compiled/interactive_splom.vg.json
index 977b8fa8e7..2b71d089be 100644
--- a/examples/compiled/interactive_splom.vg.json
+++ b/examples/compiled/interactive_splom.vg.json
@@ -281,8 +281,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -421,8 +426,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -791,8 +801,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -929,8 +939,8 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -1234,7 +1244,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Horsepower", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -1351,7 +1363,9 @@
         },
         {
           "name": "grid_tuple_fields",
-          "value": [{"field": "Horsepower", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "grid_translate_anchor",
@@ -1718,8 +1732,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -1858,8 +1877,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -2165,7 +2189,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Acceleration", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -2282,7 +2308,9 @@
         },
         {
           "name": "grid_tuple_fields",
-          "value": [{"field": "Acceleration", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "grid_translate_anchor",
@@ -2647,8 +2675,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -2785,8 +2813,8 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -3094,7 +3122,14 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Miles_per_Gallon", "channel": "x", "type": "R"}]
+          "value": [
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            }
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -3211,7 +3246,14 @@
         },
         {
           "name": "grid_tuple_fields",
-          "value": [{"field": "Miles_per_Gallon", "channel": "x", "type": "R"}]
+          "value": [
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            }
+          ]
         },
         {
           "name": "grid_translate_anchor",
@@ -3578,8 +3620,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
@@ -3718,8 +3765,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
@@ -4090,8 +4142,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
@@ -4230,8 +4287,13 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/interactive_stocks_nearest_index.vg.json b/examples/compiled/interactive_stocks_nearest_index.vg.json
index d2e215a442..a8f4da0c99 100644
--- a/examples/compiled/interactive_stocks_nearest_index.vg.json
+++ b/examples/compiled/interactive_stocks_nearest_index.vg.json
@@ -68,7 +68,7 @@
     },
     {
       "name": "index_tuple_fields",
-      "value": [{"field": "date", "channel": "x", "type": "E"}]
+      "value": [{"field": "date", "channel": "x", "type": "E", "index": 0}]
     },
     {
       "name": "index_toggle",
diff --git a/examples/compiled/isotype_grid.vg.json b/examples/compiled/isotype_grid.vg.json
index cfd0b76d02..c155427082 100644
--- a/examples/compiled/isotype_grid.vg.json
+++ b/examples/compiled/isotype_grid.vg.json
@@ -267,8 +267,8 @@
     {
       "name": "highlight_tuple_fields",
       "value": [
-        {"field": "col", "channel": "x", "type": "E"},
-        {"field": "row", "channel": "y", "type": "E"}
+        {"field": "col", "channel": "x", "type": "E", "index": 0},
+        {"field": "row", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/param_expr.vg.json b/examples/compiled/param_expr.vg.json
index ca0bd9994e..1f1370675e 100644
--- a/examples/compiled/param_expr.vg.json
+++ b/examples/compiled/param_expr.vg.json
@@ -49,7 +49,7 @@
     },
     {
       "name": "sel_tuple_fields",
-      "value": [{"type": "E", "field": "Miles_per_Gallon"}]
+      "value": [{"type": "E", "field": "Miles_per_Gallon", "index": 0}]
     },
     {
       "name": "sel_modify",
diff --git a/examples/compiled/selection_bind_cylyr.vg.json b/examples/compiled/selection_bind_cylyr.vg.json
index c4ef29ebb6..fa30918965 100644
--- a/examples/compiled/selection_bind_cylyr.vg.json
+++ b/examples/compiled/selection_bind_cylyr.vg.json
@@ -49,8 +49,8 @@
     {
       "name": "CylYr_tuple_fields",
       "value": [
-        {"type": "E", "field": "Cylinders"},
-        {"type": "E", "field": "Year"}
+        {"type": "E", "field": "Cylinders", "index": 0},
+        {"type": "E", "field": "Year", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_bind_origin.vg.json b/examples/compiled/selection_bind_origin.vg.json
index 8b6c71f01f..0872504875 100644
--- a/examples/compiled/selection_bind_origin.vg.json
+++ b/examples/compiled/selection_bind_origin.vg.json
@@ -40,7 +40,10 @@
       "name": "org_tuple",
       "update": "org_Origin !== null ? {fields: org_tuple_fields, values: [org_Origin]} : null"
     },
-    {"name": "org_tuple_fields", "value": [{"type": "E", "field": "Origin"}]},
+    {
+      "name": "org_tuple_fields",
+      "value": [{"type": "E", "field": "Origin", "index": 0}]
+    },
     {
       "name": "org_modify",
       "on": [
diff --git a/examples/compiled/selection_brush_timeunit.vg.json b/examples/compiled/selection_brush_timeunit.vg.json
index f18b6c35b9..f862206661 100644
--- a/examples/compiled/selection_brush_timeunit.vg.json
+++ b/examples/compiled/selection_brush_timeunit.vg.json
@@ -166,7 +166,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "seconds_date", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "seconds_date", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
diff --git a/examples/compiled/selection_clear_brush.vg.json b/examples/compiled/selection_clear_brush.vg.json
index b42df697ed..66b88bd753 100644
--- a/examples/compiled/selection_clear_brush.vg.json
+++ b/examples/compiled/selection_clear_brush.vg.json
@@ -12,8 +12,13 @@
         {
           "unit": "",
           "fields": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ],
           "values": [[55, 160], [13, 37]]
         }
@@ -180,8 +185,8 @@
     {
       "name": "brush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_composition_and.vg.json b/examples/compiled/selection_composition_and.vg.json
index 21ffb0e8c4..5e717e80f5 100644
--- a/examples/compiled/selection_composition_and.vg.json
+++ b/examples/compiled/selection_composition_and.vg.json
@@ -177,8 +177,8 @@
     {
       "name": "alex_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
@@ -400,8 +400,8 @@
     {
       "name": "morgan_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_composition_or.vg.json b/examples/compiled/selection_composition_or.vg.json
index df9aeacf15..3f81a8c88d 100644
--- a/examples/compiled/selection_composition_or.vg.json
+++ b/examples/compiled/selection_composition_or.vg.json
@@ -177,8 +177,8 @@
     {
       "name": "alex_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
@@ -400,8 +400,8 @@
     {
       "name": "morgan_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_concat.vg.json b/examples/compiled/selection_concat.vg.json
index 3201351e9b..d5c0552124 100644
--- a/examples/compiled/selection_concat.vg.json
+++ b/examples/compiled/selection_concat.vg.json
@@ -203,8 +203,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -507,8 +512,8 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "Displacement", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {"field": "Displacement", "channel": "x", "type": "R", "index": 0},
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
diff --git a/examples/compiled/selection_filter.vg.json b/examples/compiled/selection_filter.vg.json
index 73c168c3cd..a25da1b874 100644
--- a/examples/compiled/selection_filter.vg.json
+++ b/examples/compiled/selection_filter.vg.json
@@ -200,8 +200,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/selection_filter_composition.vg.json b/examples/compiled/selection_filter_composition.vg.json
index cdffdfbf11..2a6790911c 100644
--- a/examples/compiled/selection_filter_composition.vg.json
+++ b/examples/compiled/selection_filter_composition.vg.json
@@ -200,8 +200,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/selection_filter_false.vg.json b/examples/compiled/selection_filter_false.vg.json
index 9609103d4a..a21f86434d 100644
--- a/examples/compiled/selection_filter_false.vg.json
+++ b/examples/compiled/selection_filter_false.vg.json
@@ -200,8 +200,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/selection_filter_true.vg.json b/examples/compiled/selection_filter_true.vg.json
index 73c168c3cd..a25da1b874 100644
--- a/examples/compiled/selection_filter_true.vg.json
+++ b/examples/compiled/selection_filter_true.vg.json
@@ -200,8 +200,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/selection_heatmap.vg.json b/examples/compiled/selection_heatmap.vg.json
index 03f1a9feb1..6cdc2b486c 100644
--- a/examples/compiled/selection_heatmap.vg.json
+++ b/examples/compiled/selection_heatmap.vg.json
@@ -4,7 +4,13 @@
   "padding": 5,
   "style": "cell",
   "data": [
-    {"name": "highlight_store"},
+    {
+      "name": "highlight_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "values": [
@@ -63,7 +69,7 @@
     },
     {
       "name": "highlight_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "highlight_toggle",
@@ -99,21 +105,21 @@
           "fill": {"scale": "fill", "field": "count"},
           "stroke": [
             {
-              "test": "length(data(\"highlight_store\")) && vlSelectionTest(\"highlight_store\", datum)",
+              "test": "length(data(\"highlight_store\")) && vlSelectionIdTest(\"highlight_store\", datum)",
               "value": "black"
             },
             {"value": null}
           ],
           "opacity": [
             {
-              "test": "!length(data(\"highlight_store\")) || vlSelectionTest(\"highlight_store\", datum)",
+              "test": "!length(data(\"highlight_store\")) || vlSelectionIdTest(\"highlight_store\", datum)",
               "value": 1
             },
             {"value": 0.5}
           ],
           "zindex": [
             {
-              "test": "!length(data(\"highlight_store\")) || vlSelectionTest(\"highlight_store\", datum)",
+              "test": "!length(data(\"highlight_store\")) || vlSelectionIdTest(\"highlight_store\", datum)",
               "value": 1
             },
             {"value": 0}
diff --git a/examples/compiled/selection_insert.vg.json b/examples/compiled/selection_insert.vg.json
index a8ab7d3ec1..625f3a8445 100644
--- a/examples/compiled/selection_insert.vg.json
+++ b/examples/compiled/selection_insert.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -45,7 +51,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_modify",
@@ -69,7 +75,7 @@
           "opacity": {"value": 0.7},
           "fill": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
diff --git a/examples/compiled/selection_interval_mark_style.vg.json b/examples/compiled/selection_interval_mark_style.vg.json
index 4382b9bfc6..334a424e00 100644
--- a/examples/compiled/selection_interval_mark_style.vg.json
+++ b/examples/compiled/selection_interval_mark_style.vg.json
@@ -177,8 +177,8 @@
     {
       "name": "alex_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
@@ -400,8 +400,8 @@
     {
       "name": "morgan_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_layer_bar_month.vg.json b/examples/compiled/selection_layer_bar_month.vg.json
index 5e6abd859c..9cd9257625 100644
--- a/examples/compiled/selection_layer_bar_month.vg.json
+++ b/examples/compiled/selection_layer_bar_month.vg.json
@@ -152,7 +152,9 @@
     },
     {
       "name": "brush_tuple_fields",
-      "value": [{"field": "month_date", "channel": "x", "type": "E"}]
+      "value": [
+        {"field": "month_date", "channel": "x", "type": "E", "index": 0}
+      ]
     },
     {
       "name": "brush_translate_anchor",
diff --git a/examples/compiled/selection_multi_condition.vg.json b/examples/compiled/selection_multi_condition.vg.json
index 1428dc4661..14ba65d247 100644
--- a/examples/compiled/selection_multi_condition.vg.json
+++ b/examples/compiled/selection_multi_condition.vg.json
@@ -8,7 +8,13 @@
   "style": "cell",
   "data": [
     {"name": "brush_store"},
-    {"name": "hoverbrush_store"},
+    {
+      "name": "hoverbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -178,8 +184,8 @@
     {
       "name": "brush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
@@ -275,7 +281,7 @@
     },
     {
       "name": "hoverbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "hoverbrush_toggle",
@@ -351,7 +357,7 @@
           "fill": {"value": "transparent"},
           "stroke": [
             {
-              "test": "!length(data(\"hoverbrush_store\")) || vlSelectionTest(\"hoverbrush_store\", datum)",
+              "test": "!length(data(\"hoverbrush_store\")) || vlSelectionIdTest(\"hoverbrush_store\", datum)",
               "value": "teal"
             },
             {
diff --git a/examples/compiled/selection_project_binned_interval.vg.json b/examples/compiled/selection_project_binned_interval.vg.json
index 0dac11e87c..62c8ddad7e 100644
--- a/examples/compiled/selection_project_binned_interval.vg.json
+++ b/examples/compiled/selection_project_binned_interval.vg.json
@@ -167,7 +167,9 @@
     },
     {
       "name": "brush_tuple_fields",
-      "value": [{"field": "Acceleration", "channel": "x", "type": "R"}]
+      "value": [
+        {"field": "Acceleration", "channel": "x", "type": "R", "index": 0}
+      ]
     },
     {
       "name": "brush_translate_anchor",
diff --git a/examples/compiled/selection_project_interval.vg.json b/examples/compiled/selection_project_interval.vg.json
index b8b69a7333..a8cc0afff1 100644
--- a/examples/compiled/selection_project_interval.vg.json
+++ b/examples/compiled/selection_project_interval.vg.json
@@ -166,8 +166,8 @@
     {
       "name": "pts_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_project_interval_x.vg.json b/examples/compiled/selection_project_interval_x.vg.json
index a6c7b0a79e..064c8df463 100644
--- a/examples/compiled/selection_project_interval_x.vg.json
+++ b/examples/compiled/selection_project_interval_x.vg.json
@@ -111,7 +111,7 @@
     },
     {
       "name": "pts_tuple_fields",
-      "value": [{"field": "Cylinders", "channel": "x", "type": "E"}]
+      "value": [{"field": "Cylinders", "channel": "x", "type": "E", "index": 0}]
     },
     {
       "name": "pts_translate_anchor",
diff --git a/examples/compiled/selection_project_interval_x_y.vg.json b/examples/compiled/selection_project_interval_x_y.vg.json
index b8b69a7333..a8cc0afff1 100644
--- a/examples/compiled/selection_project_interval_x_y.vg.json
+++ b/examples/compiled/selection_project_interval_x_y.vg.json
@@ -166,8 +166,8 @@
     {
       "name": "pts_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_project_interval_y.vg.json b/examples/compiled/selection_project_interval_y.vg.json
index 7b2f1c4eb3..11436550ea 100644
--- a/examples/compiled/selection_project_interval_y.vg.json
+++ b/examples/compiled/selection_project_interval_y.vg.json
@@ -111,7 +111,7 @@
     },
     {
       "name": "pts_tuple_fields",
-      "value": [{"field": "Origin", "channel": "y", "type": "E"}]
+      "value": [{"field": "Origin", "channel": "y", "type": "E", "index": 0}]
     },
     {
       "name": "pts_translate_anchor",
diff --git a/examples/compiled/selection_project_multi.vg.json b/examples/compiled/selection_project_multi.vg.json
index 6510ed917c..4bc142370f 100644
--- a/examples/compiled/selection_project_multi.vg.json
+++ b/examples/compiled/selection_project_multi.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "pts_store"},
+    {
+      "name": "pts_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -43,7 +49,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "_vgsid_"}]},
+    {
+      "name": "pts_tuple_fields",
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
+    },
     {
       "name": "pts_toggle",
       "value": false,
@@ -78,7 +87,7 @@
           "fill": {"value": "transparent"},
           "stroke": [
             {
-              "test": "!length(data(\"pts_store\")) || vlSelectionTest(\"pts_store\", datum)",
+              "test": "!length(data(\"pts_store\")) || vlSelectionIdTest(\"pts_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
@@ -92,7 +101,7 @@
           "y": {"scale": "y", "field": "Miles_per_Gallon"},
           "size": [
             {
-              "test": "!length(data(\"pts_store\")) || vlSelectionTest(\"pts_store\", datum)",
+              "test": "!length(data(\"pts_store\")) || vlSelectionIdTest(\"pts_store\", datum)",
               "value": 200
             },
             {"value": 50}
diff --git a/examples/compiled/selection_project_multi_cylinders.vg.json b/examples/compiled/selection_project_multi_cylinders.vg.json
index 67e9703503..de5aea5200 100644
--- a/examples/compiled/selection_project_multi_cylinders.vg.json
+++ b/examples/compiled/selection_project_multi_cylinders.vg.json
@@ -44,7 +44,7 @@
     },
     {
       "name": "pts_tuple_fields",
-      "value": [{"type": "E", "field": "Cylinders"}]
+      "value": [{"type": "E", "field": "Cylinders", "index": 0}]
     },
     {
       "name": "pts_toggle",
diff --git a/examples/compiled/selection_project_multi_cylinders_origin.vg.json b/examples/compiled/selection_project_multi_cylinders_origin.vg.json
index 87c82d1174..a55a465bc7 100644
--- a/examples/compiled/selection_project_multi_cylinders_origin.vg.json
+++ b/examples/compiled/selection_project_multi_cylinders_origin.vg.json
@@ -45,8 +45,8 @@
     {
       "name": "pts_tuple_fields",
       "value": [
-        {"type": "E", "field": "Cylinders"},
-        {"type": "E", "field": "Origin"}
+        {"type": "E", "field": "Cylinders", "index": 0},
+        {"type": "E", "field": "Origin", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_project_multi_origin.vg.json b/examples/compiled/selection_project_multi_origin.vg.json
index 979e2de262..67b71eec0a 100644
--- a/examples/compiled/selection_project_multi_origin.vg.json
+++ b/examples/compiled/selection_project_multi_origin.vg.json
@@ -42,7 +42,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "Origin"}]},
+    {
+      "name": "pts_tuple_fields",
+      "value": [{"type": "E", "field": "Origin", "index": 0}]
+    },
     {
       "name": "pts_toggle",
       "value": false,
diff --git a/examples/compiled/selection_project_single.vg.json b/examples/compiled/selection_project_single.vg.json
index 5cee51d653..4fe0734507 100644
--- a/examples/compiled/selection_project_single.vg.json
+++ b/examples/compiled/selection_project_single.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "pts_store"},
+    {
+      "name": "pts_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -43,7 +49,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "_vgsid_"}]},
+    {
+      "name": "pts_tuple_fields",
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
+    },
     {
       "name": "pts_modify",
       "on": [
@@ -67,7 +76,7 @@
           "fill": {"value": "transparent"},
           "stroke": [
             {
-              "test": "!length(data(\"pts_store\")) || vlSelectionTest(\"pts_store\", datum)",
+              "test": "!length(data(\"pts_store\")) || vlSelectionIdTest(\"pts_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
@@ -81,7 +90,7 @@
           "y": {"scale": "y", "field": "Miles_per_Gallon"},
           "size": [
             {
-              "test": "!length(data(\"pts_store\")) || vlSelectionTest(\"pts_store\", datum)",
+              "test": "!length(data(\"pts_store\")) || vlSelectionIdTest(\"pts_store\", datum)",
               "value": 200
             },
             {"value": 50}
diff --git a/examples/compiled/selection_project_single_cylinders.vg.json b/examples/compiled/selection_project_single_cylinders.vg.json
index 9094df55e4..4b661e34b0 100644
--- a/examples/compiled/selection_project_single_cylinders.vg.json
+++ b/examples/compiled/selection_project_single_cylinders.vg.json
@@ -44,7 +44,7 @@
     },
     {
       "name": "pts_tuple_fields",
-      "value": [{"type": "E", "field": "Cylinders"}]
+      "value": [{"type": "E", "field": "Cylinders", "index": 0}]
     },
     {
       "name": "pts_modify",
diff --git a/examples/compiled/selection_project_single_cylinders_origin.vg.json b/examples/compiled/selection_project_single_cylinders_origin.vg.json
index 67a3fa6102..e7850dbdf1 100644
--- a/examples/compiled/selection_project_single_cylinders_origin.vg.json
+++ b/examples/compiled/selection_project_single_cylinders_origin.vg.json
@@ -45,8 +45,8 @@
     {
       "name": "pts_tuple_fields",
       "value": [
-        {"type": "E", "field": "Cylinders"},
-        {"type": "E", "field": "Origin"}
+        {"type": "E", "field": "Cylinders", "index": 0},
+        {"type": "E", "field": "Origin", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_project_single_origin.vg.json b/examples/compiled/selection_project_single_origin.vg.json
index 87161fb20d..8153205580 100644
--- a/examples/compiled/selection_project_single_origin.vg.json
+++ b/examples/compiled/selection_project_single_origin.vg.json
@@ -42,7 +42,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "Origin"}]},
+    {
+      "name": "pts_tuple_fields",
+      "value": [{"type": "E", "field": "Origin", "index": 0}]
+    },
     {
       "name": "pts_modify",
       "on": [
diff --git a/examples/compiled/selection_resolution_global.vg.json b/examples/compiled/selection_resolution_global.vg.json
index ca0a20cd5c..fd8411e5e0 100644
--- a/examples/compiled/selection_resolution_global.vg.json
+++ b/examples/compiled/selection_resolution_global.vg.json
@@ -239,8 +239,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -651,8 +656,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -1000,7 +1005,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Horsepower", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -1409,8 +1416,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -1760,7 +1772,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Acceleration", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -2167,8 +2181,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -2520,7 +2534,14 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Miles_per_Gallon", "channel": "x", "type": "R"}]
+          "value": [
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            }
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -2929,8 +2950,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
@@ -3343,8 +3369,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/selection_resolution_intersect.vg.json b/examples/compiled/selection_resolution_intersect.vg.json
index be6ea11495..9debdab7e2 100644
--- a/examples/compiled/selection_resolution_intersect.vg.json
+++ b/examples/compiled/selection_resolution_intersect.vg.json
@@ -239,8 +239,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -603,8 +608,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -904,7 +909,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Horsepower", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -1265,8 +1272,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -1568,7 +1580,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Acceleration", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -1927,8 +1941,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -2232,7 +2246,14 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Miles_per_Gallon", "channel": "x", "type": "R"}]
+          "value": [
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            }
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -2593,8 +2614,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
@@ -2959,8 +2985,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/selection_resolution_union.vg.json b/examples/compiled/selection_resolution_union.vg.json
index 4e64c836da..33f048da54 100644
--- a/examples/compiled/selection_resolution_union.vg.json
+++ b/examples/compiled/selection_resolution_union.vg.json
@@ -239,8 +239,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -603,8 +608,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Horsepower", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {"field": "Horsepower", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -904,7 +909,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Horsepower", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -1265,8 +1272,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Miles_per_Gallon", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            },
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -1568,7 +1580,9 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Acceleration", "channel": "x", "type": "R"}]
+          "value": [
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0}
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -1927,8 +1941,8 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Acceleration", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {"field": "Acceleration", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -2232,7 +2246,14 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "Miles_per_Gallon", "channel": "x", "type": "R"}]
+          "value": [
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "x",
+              "type": "R",
+              "index": 0
+            }
+          ]
         },
         {
           "name": "brush_translate_anchor",
@@ -2593,8 +2614,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Acceleration", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Acceleration", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
@@ -2959,8 +2985,13 @@
         {
           "name": "brush_tuple_fields",
           "value": [
-            {"field": "Horsepower", "channel": "x", "type": "R"},
-            {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+            {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+            {
+              "field": "Miles_per_Gallon",
+              "channel": "y",
+              "type": "R",
+              "index": 1
+            }
           ]
         },
         {
diff --git a/examples/compiled/selection_toggle_altKey.vg.json b/examples/compiled/selection_toggle_altKey.vg.json
index 362b0a21d9..168e9c6462 100644
--- a/examples/compiled/selection_toggle_altKey.vg.json
+++ b/examples/compiled/selection_toggle_altKey.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -45,7 +51,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -80,7 +86,7 @@
           "opacity": {"value": 0.7},
           "fill": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
diff --git a/examples/compiled/selection_toggle_altKey_shiftKey.vg.json b/examples/compiled/selection_toggle_altKey_shiftKey.vg.json
index 580346ab5f..a19d358759 100644
--- a/examples/compiled/selection_toggle_altKey_shiftKey.vg.json
+++ b/examples/compiled/selection_toggle_altKey_shiftKey.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -45,7 +51,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -80,7 +86,7 @@
           "opacity": {"value": 0.7},
           "fill": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
diff --git a/examples/compiled/selection_toggle_shiftKey.vg.json b/examples/compiled/selection_toggle_shiftKey.vg.json
index 74e6934c78..226b03aa2f 100644
--- a/examples/compiled/selection_toggle_shiftKey.vg.json
+++ b/examples/compiled/selection_toggle_shiftKey.vg.json
@@ -6,7 +6,13 @@
   "height": 200,
   "style": "cell",
   "data": [
-    {"name": "paintbrush_store"},
+    {
+      "name": "paintbrush_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -45,7 +51,7 @@
     },
     {
       "name": "paintbrush_tuple_fields",
-      "value": [{"type": "E", "field": "_vgsid_"}]
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
     },
     {
       "name": "paintbrush_toggle",
@@ -80,7 +86,7 @@
           "opacity": {"value": 0.7},
           "fill": [
             {
-              "test": "!length(data(\"paintbrush_store\")) || vlSelectionTest(\"paintbrush_store\", datum)",
+              "test": "!length(data(\"paintbrush_store\")) || vlSelectionIdTest(\"paintbrush_store\", datum)",
               "scale": "color",
               "field": "Cylinders"
             },
diff --git a/examples/compiled/selection_translate_brush_drag.vg.json b/examples/compiled/selection_translate_brush_drag.vg.json
index d1cdcabe39..e39738fa75 100644
--- a/examples/compiled/selection_translate_brush_drag.vg.json
+++ b/examples/compiled/selection_translate_brush_drag.vg.json
@@ -171,8 +171,8 @@
     {
       "name": "brush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_translate_brush_shift-drag.vg.json b/examples/compiled/selection_translate_brush_shift-drag.vg.json
index 98fb5ffac4..8422d55fbb 100644
--- a/examples/compiled/selection_translate_brush_shift-drag.vg.json
+++ b/examples/compiled/selection_translate_brush_shift-drag.vg.json
@@ -171,8 +171,8 @@
     {
       "name": "brush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_translate_scatterplot_drag.vg.json b/examples/compiled/selection_translate_scatterplot_drag.vg.json
index 36a295788c..a879fbb10a 100644
--- a/examples/compiled/selection_translate_scatterplot_drag.vg.json
+++ b/examples/compiled/selection_translate_scatterplot_drag.vg.json
@@ -68,8 +68,8 @@
     {
       "name": "grid_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_translate_scatterplot_shift-drag.vg.json b/examples/compiled/selection_translate_scatterplot_shift-drag.vg.json
index 3d2fb1a988..6c011944ef 100644
--- a/examples/compiled/selection_translate_scatterplot_shift-drag.vg.json
+++ b/examples/compiled/selection_translate_scatterplot_shift-drag.vg.json
@@ -68,8 +68,8 @@
     {
       "name": "grid_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_type_interval.vg.json b/examples/compiled/selection_type_interval.vg.json
index b8b69a7333..a8cc0afff1 100644
--- a/examples/compiled/selection_type_interval.vg.json
+++ b/examples/compiled/selection_type_interval.vg.json
@@ -166,8 +166,8 @@
     {
       "name": "pts_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_type_interval_invert.vg.json b/examples/compiled/selection_type_interval_invert.vg.json
index 8233581046..dff0c4aed0 100644
--- a/examples/compiled/selection_type_interval_invert.vg.json
+++ b/examples/compiled/selection_type_interval_invert.vg.json
@@ -166,8 +166,8 @@
     {
       "name": "pts_tuple_fields",
       "value": [
-        {"field": "Cylinders", "channel": "x", "type": "E"},
-        {"field": "Origin", "channel": "y", "type": "E"}
+        {"field": "Cylinders", "channel": "x", "type": "E", "index": 0},
+        {"field": "Origin", "channel": "y", "type": "E", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_type_point.vg.json b/examples/compiled/selection_type_point.vg.json
index b708485bfc..9452e6f16f 100644
--- a/examples/compiled/selection_type_point.vg.json
+++ b/examples/compiled/selection_type_point.vg.json
@@ -4,7 +4,13 @@
   "padding": 5,
   "style": "cell",
   "data": [
-    {"name": "pts_store"},
+    {
+      "name": "pts_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -52,7 +58,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "_vgsid_"}]},
+    {
+      "name": "pts_tuple_fields",
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
+    },
     {
       "name": "pts_toggle",
       "value": false,
@@ -85,7 +94,7 @@
         "update": {
           "fill": [
             {
-              "test": "!length(data(\"pts_store\")) || vlSelectionTest(\"pts_store\", datum)",
+              "test": "!length(data(\"pts_store\")) || vlSelectionIdTest(\"pts_store\", datum)",
               "scale": "color",
               "field": "__count"
             },
diff --git a/examples/compiled/selection_type_single_dblclick.vg.json b/examples/compiled/selection_type_single_dblclick.vg.json
index 3af3267c2f..d75fe166a4 100644
--- a/examples/compiled/selection_type_single_dblclick.vg.json
+++ b/examples/compiled/selection_type_single_dblclick.vg.json
@@ -4,7 +4,13 @@
   "padding": 5,
   "style": "cell",
   "data": [
-    {"name": "pts_store"},
+    {
+      "name": "pts_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -52,7 +58,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "_vgsid_"}]},
+    {
+      "name": "pts_tuple_fields",
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
+    },
     {
       "name": "pts_toggle",
       "value": false,
@@ -85,7 +94,7 @@
         "update": {
           "fill": [
             {
-              "test": "!length(data(\"pts_store\")) || vlSelectionTest(\"pts_store\", datum)",
+              "test": "!length(data(\"pts_store\")) || vlSelectionIdTest(\"pts_store\", datum)",
               "scale": "color",
               "field": "__count"
             },
diff --git a/examples/compiled/selection_type_single_mouseover.vg.json b/examples/compiled/selection_type_single_mouseover.vg.json
index 074bf81eac..ee49459723 100644
--- a/examples/compiled/selection_type_single_mouseover.vg.json
+++ b/examples/compiled/selection_type_single_mouseover.vg.json
@@ -4,7 +4,13 @@
   "padding": 5,
   "style": "cell",
   "data": [
-    {"name": "pts_store"},
+    {
+      "name": "pts_store",
+      "transform": [
+        {"type": "formula", "expr": "datum.values[0]", "as": "_vgsid_"},
+        {"type": "collect", "sort": {"field": "_vgsid_"}}
+      ]
+    },
     {
       "name": "source_0",
       "url": "data/cars.json",
@@ -52,7 +58,10 @@
         {"events": [{"source": "view", "type": "dblclick"}], "update": "null"}
       ]
     },
-    {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "_vgsid_"}]},
+    {
+      "name": "pts_tuple_fields",
+      "value": [{"type": "E", "field": "_vgsid_", "index": 0}]
+    },
     {
       "name": "pts_toggle",
       "value": false,
@@ -85,7 +94,7 @@
         "update": {
           "fill": [
             {
-              "test": "!length(data(\"pts_store\")) || vlSelectionTest(\"pts_store\", datum)",
+              "test": "!length(data(\"pts_store\")) || vlSelectionIdTest(\"pts_store\", datum)",
               "scale": "color",
               "field": "__count"
             },
diff --git a/examples/compiled/selection_zoom_brush_shift-wheel.vg.json b/examples/compiled/selection_zoom_brush_shift-wheel.vg.json
index 486f386940..1caed4c748 100644
--- a/examples/compiled/selection_zoom_brush_shift-wheel.vg.json
+++ b/examples/compiled/selection_zoom_brush_shift-wheel.vg.json
@@ -171,8 +171,8 @@
     {
       "name": "brush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_zoom_brush_wheel.vg.json b/examples/compiled/selection_zoom_brush_wheel.vg.json
index d1cdcabe39..e39738fa75 100644
--- a/examples/compiled/selection_zoom_brush_wheel.vg.json
+++ b/examples/compiled/selection_zoom_brush_wheel.vg.json
@@ -171,8 +171,8 @@
     {
       "name": "brush_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_zoom_scatterplot_shift-wheel.vg.json b/examples/compiled/selection_zoom_scatterplot_shift-wheel.vg.json
index 878cb75f29..19017008f7 100644
--- a/examples/compiled/selection_zoom_scatterplot_shift-wheel.vg.json
+++ b/examples/compiled/selection_zoom_scatterplot_shift-wheel.vg.json
@@ -68,8 +68,8 @@
     {
       "name": "grid_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/selection_zoom_scatterplot_wheel.vg.json b/examples/compiled/selection_zoom_scatterplot_wheel.vg.json
index 36a295788c..a879fbb10a 100644
--- a/examples/compiled/selection_zoom_scatterplot_wheel.vg.json
+++ b/examples/compiled/selection_zoom_scatterplot_wheel.vg.json
@@ -68,8 +68,8 @@
     {
       "name": "grid_tuple_fields",
       "value": [
-        {"field": "Horsepower", "channel": "x", "type": "R"},
-        {"field": "Miles_per_Gallon", "channel": "y", "type": "R"}
+        {"field": "Horsepower", "channel": "x", "type": "R", "index": 0},
+        {"field": "Miles_per_Gallon", "channel": "y", "type": "R", "index": 1}
       ]
     },
     {
diff --git a/examples/compiled/trellis_selections.vg.json b/examples/compiled/trellis_selections.vg.json
index c3150da132..36b89e1f1f 100644
--- a/examples/compiled/trellis_selections.vg.json
+++ b/examples/compiled/trellis_selections.vg.json
@@ -236,7 +236,7 @@
         },
         {
           "name": "brush_tuple_fields",
-          "value": [{"field": "X", "channel": "x", "type": "R"}]
+          "value": [{"field": "X", "channel": "x", "type": "R", "index": 0}]
         },
         {
           "name": "brush_translate_anchor",
@@ -369,8 +369,8 @@
         {
           "name": "grid_tuple_fields",
           "value": [
-            {"field": "X", "channel": "x", "type": "R"},
-            {"field": "Y", "channel": "y", "type": "R"}
+            {"field": "X", "channel": "x", "type": "R", "index": 0},
+            {"field": "Y", "channel": "y", "type": "R", "index": 1}
           ]
         },
         {
@@ -444,7 +444,10 @@
           "name": "xenc_tuple",
           "update": "xenc_X !== null ? {fields: xenc_tuple_fields, values: [xenc_X]} : null"
         },
-        {"name": "xenc_tuple_fields", "value": [{"type": "E", "field": "X"}]},
+        {
+          "name": "xenc_tuple_fields",
+          "value": [{"type": "E", "field": "X", "index": 0}]
+        },
         {
           "name": "xenc_modify",
           "on": [
diff --git a/examples/compiled/vconcat_flatten.vg.json b/examples/compiled/vconcat_flatten.vg.json
index 550666178a..281ec56e0e 100644
--- a/examples/compiled/vconcat_flatten.vg.json
+++ b/examples/compiled/vconcat_flatten.vg.json
@@ -116,7 +116,10 @@
             }
           ]
         },
-        {"name": "pts_tuple_fields", "value": [{"type": "E", "field": "id"}]},
+        {
+          "name": "pts_tuple_fields",
+          "value": [{"type": "E", "field": "id", "index": 0}]
+        },
         {
           "name": "pts_toggle",
           "value": false,