Postgres version command incompatible with Redshift

[CaptainCrucial]

When connecting using the Postgres driver, the afterConnect method is running the SQLSHOW server_version; as part of feature support detection.

This command works on postgres and cockroachdb, but is incompatible with the redshift database.

This command could be adjusted to use the SELECT version(); command which is supported across all of these database types.

I've patched this command locally and successfully connected and read data using typeorm:

diff --git a/src/driver/postgres/PostgresDriver.ts b/src/driver/postgres/PostgresDriver.ts
index 92142ba53..0dfad6d7a 100644
--- a/src/driver/postgres/PostgresDriver.ts
+++ b/src/driver/postgres/PostgresDriver.ts
@@ -375,13 +375,16 @@ export class PostgresDriver implements Driver {
 
         const results = (await this.executeQuery(
             connection,
-            "SHOW server_version;",
+            "SELECT version();",
         )) as {
             rows: {
-                server_version: string
+                version: string
             }[]
         }
-        const versionString = results.rows[0].server_version
+        const versionString = results.rows[0].version.replace(
+            /^PostgreSQL ([\d\.]+) .*$/,
+            "$1",
+        )
         this.isGeneratedColumnsSupported = VersionUtils.isGreaterOrEqual(
             versionString,
             "12.0",
diff --git a/src/driver/postgres/PostgresQueryRunner.ts b/src/driver/postgres/PostgresQueryRunner.ts
index e8aaa3eaa..4a5c84655 100644
--- a/src/driver/postgres/PostgresQueryRunner.ts
+++ b/src/driver/postgres/PostgresQueryRunner.ts
@@ -3989,8 +3989,8 @@ export class PostgresQueryRunner
      * Loads Postgres version.
      */
     protected async getVersion(): Promise<string> {
-        const result = await this.query(`SHOW SERVER_VERSION`)
-        return result[0]["server_version"]
+        const result = await this.query(`SELECT version()`)
+        return result[0]["version"].replace(/^PostgreSQL ([\d\.]+) .*$/, "$1")
     }
 
     /**
diff --git a/test/functional/cube/postgres/cube-postgres.ts b/test/functional/cube/postgres/cube-postgres.ts
index f70baf10b..d5e81a68c 100644
--- a/test/functional/cube/postgres/cube-postgres.ts
+++ b/test/functional/cube/postgres/cube-postgres.ts
@@ -109,10 +109,11 @@ describe("cube-postgres", () => {
                 // Get Postgres version because zero-length cubes are not legal
                 // on all Postgres versions. Zero-length cubes are only tested
                 // to be working on Postgres version >=10.6.
-                const [{ server_version }] = await connection.query(
-                    "SHOW server_version",
-                )
-                const semverArray = server_version.split(".").map(Number)
+                const [{ version }] = await connection.query("SELECT version()")
+                const semverArray = version
+                    .replace(/^PostgreSQL ([\d\.]+) .*$/, "$1")
+                    .split(".")
+                    .map(Number)
                 if (!(semverArray[0] >= 10 && semverArray[1] >= 6)) {
                     return
                 }

Good to get your thoughts