colocation: enforce colocated reloption behavior

Summary:
Enforce the behavior of the `colocated` reloption from `CREATE TABLE`.
By default, inherit the `colocated` option from the database.  Then,
allow overrides by the reloption specified by the user _only if the
database is colocated_.  Allow the user to redundantly specify
`colocated = false` for a non-colocated database; error when the user
specifies `colocated = true` for a non-colocated database.

Depends on D8207

Test Plan:
* `./yb_build.sh --cxx-test pgwrapper_pg_libpq-test --gtest_filter
  PgLibPqTest.TableColocation`
* `./yb_build.sh --java-test org.yb.pgsql.TestPgRegressBetaFeatures`

Reviewers: neha

Reviewed By: neha

Subscribers: yql

Differential Revision: https://phabricator.dev.yugabyte.com/D8218

src/postgres/src/backend/commands/ybccmds.c

@@ -483,18 +483,29 @@ YBCCreateTable(CreateStmt *stmt, char relkind, TupleDesc desc, Oid relationId, O
 		}
 	}
 
-	ListCell	*opt_cell;
-	// Set the default option to true so that tables created in a colocated database will be
-	// colocated by default. For regular database, this argument will be ignored.
-	bool		colocated = true;
-	/* Scan list to see if colocated was included */
+	/* By default, inherit the colocated option from the database */
+	bool colocated = MyDatabaseColocated;
+
+	/* Handle user-supplied colocated reloption */
+	ListCell *opt_cell;
 	foreach(opt_cell, stmt->options)
 	{
 		DefElem *def = (DefElem *) lfirst(opt_cell);
 
 		if (strcmp(def->defname, "colocated") == 0)
 		{
-			colocated = defGetBoolean(def);
+			bool colocated_relopt = defGetBoolean(def);
+			if (MyDatabaseColocated)
+				colocated = colocated_relopt;
+			else if (colocated_relopt)
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("cannot set colocated true on a non-colocated"
+								" database")));
+			/* The following break is fine because there should only be one
+			 * colocated reloption at this point due to checks in
+			 * parseRelOptions */
+			break;
 		}
 	}
 

src/postgres/src/test/regress/expected/yb_feature_colocation.out

@@ -1,6 +1,12 @@
 --
 -- Colocation
 --
+-- CREATE TABLE on non-colocated database
+CREATE TABLE tab_colo (a INT) WITH (colocated = true);
+ERROR:  cannot set colocated true on a non-colocated database
+CREATE TABLE tab_noco (a INT) WITH (colocated = false);
+DROP TABLE tab_noco;
+-- CREATE DATABASE colocated
 CREATE DATABASE colocation_test colocated = true;
 \c colocation_test
 -- CREATE TABLE

src/postgres/src/test/regress/sql/yb_feature_colocation.sql

@@ -2,6 +2,14 @@
 -- Colocation
 --
 
+-- CREATE TABLE on non-colocated database
+
+CREATE TABLE tab_colo (a INT) WITH (colocated = true);
+CREATE TABLE tab_noco (a INT) WITH (colocated = false);
+DROP TABLE tab_noco;
+
+-- CREATE DATABASE colocated
+
 CREATE DATABASE colocation_test colocated = true;
 \c colocation_test