Use separate PostgreSQL schemas for sprocs

prairielib/lib/sql-db.js

@@ -7,6 +7,8 @@ const { promisify } = require('util');
 
 const error = require('./error');
 
+let searchSchema = null;
+
 /**
  * Formats a string for debugging.
  *
@@ -180,7 +182,65 @@ module.exports.getClient = function(callback) {
             }
             return ERR(err, callback); // unconditionally return
         }
-        callback(null, client, done);
+        if (searchSchema != null) {
+            const setSearchPathSql = `SET search_path TO ${searchSchema},public`;
+            module.exports.queryWithClient(client, setSearchPathSql, {}, (err) => {
+                if (err) {
+                    done(client);
+                    return ERR(err, callback); // unconditionally return
+                }
+                callback(null, client, done);
+            });
+        } else {
+            callback(null, client, done);
+        }
+    });
+};
+
+/**
+ * Set the schema to use for the search path.
+ *
+ * @param {string} schema - The schema name to use (can be "null" to unset the search path)
+ * @param {(error: Error | null) => void} callback
+ */
+module.exports.setSearchSchema = function(schema, callback) {
+    searchSchema = schema;
+    module.exports.query('CREATE SCHEMA ' + schema, [], (err) => {
+        if (ERR(err, callback)) return;
+        callback(null);
+    });
+};
+
+/**
+ * Get the schema that is currently used for the search path.
+ *
+ * @return {string} schema in use (may be "null" to indicate no schema)
+ */
+module.exports.getSearchSchema = function() {
+    return searchSchema;
+};
+
+/**
+ * Generate, set, and return a random schema name.
+ *
+ * @param {string} prefix - The prefix of the new schema
+ * @param {(error: Error | null, schema: String) => void} callback
+ */
+module.exports.setRandomSearchSchema = function(prefix, callback) {
+    // truncated prefix (max 28 characters)
+    const truncPrefix = prefix.substring(30);
+    // 27-character timestamp in format YYYY-MM-DDTHH-MM-SS-SSSZ
+    const timestamp = (new Date()).toISOString().replace(/-/g, '_').replace(/:/g, '_').replace(/[.]/g, '_');
+    // random 6-character suffix to avoid clashes (approx 2 billion values)
+    const chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('');
+    const suffix = _.times(6, function() {return _.sample(chars);}).join('');
+
+    // schema is guaranteed to have length at most 63 (= 28 + 1 + 27 + 1 + 6)
+    // which is the default PostgreSQL identifier limit
+    const schema = `${truncPrefix}_${timestamp}_${suffix}`;
+    module.exports.setSearchSchema(schema, (err) => {
+        if (ERR(err, callback)) return;
+        callback(null, schema);
     });
 };
 
@@ -419,14 +479,35 @@ module.exports.query = function(sql, params, callback) {
             return true;
         };
         if (handleError(err)) return;
-        paramsToArray(sql, params, function(err, newSql, newParams) {
-            if (err) err = error.addData(err, {sql: sql, sqlParams: params});
+
+        const setSearchPath = function(callback) {
+            if (searchSchema != null) {
+                const setSearchPathSql = `SET search_path TO ${searchSchema},public`;
+                module.exports.queryWithClient(client, setSearchPathSql, {}, (err) => {
+                    if (err) {
+                        if (client) {
+                            done(client);
+                        }
+                        return ERR(err, callback); // unconditionally return
+                    }
+                    callback(null);
+                });
+            } else {
+                callback(null);
+            }
+        };
+
+        setSearchPath(function (err) {
             if (ERR(err, callback)) return;
-            client.query(newSql, newParams, function(err, result) {
-                if (handleError(err)) return;
-                done();
-                debug('query() success', 'rowCount:', result.rowCount);
-                callback(null, result);
+            paramsToArray(sql, params, function(err, newSql, newParams) {
+                if (err) err = error.addData(err, {sql: sql, sqlParams: params});
+                if (ERR(err, callback)) return;
+                client.query(newSql, newParams, function(err, result) {
+                    if (handleError(err)) return;
+                    done();
+                    debug('query() success', 'rowCount:', result.rowCount);
+                    callback(null, result);
+                });
             });
         });
     });

server.js

@@ -1136,6 +1136,12 @@ if (config.startServer) {
                 callback(null);
             });
         },
+        function(callback) {
+            sqldb.setRandomSearchSchema(config.instanceId, (err) => {
+                if (ERR(err, callback)) return;
+                callback(null);
+            });
+        },
         function(callback) {
             sprocs.init(function(err) {
                 if (ERR(err, callback)) return;