Handle CREATE TABLE IF NOT EXISTS correctly

In XL we rewrite CTAS as CREATE TABLE followed by INSERT INTO. If the target
table already exists, we now issue a notice for the first step and skip the
second step completely. The ruleutils also now handles INE correctly for CTAS

2 files changed, 20 insertions, 2 deletions

diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index fa1d07777e..48fcd51836 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -3858,10 +3858,27 @@ QueryRewriteCTAS(Query *parsetree)
 
 	relation = stmt->into->rel;
 
+	if (stmt->if_not_exists)
+	{
+		Oid			nspid;
+
+		nspid = RangeVarGetCreationNamespace(stmt->into->rel);
+
+		if (get_relname_relid(stmt->into->rel->relname, nspid))
+		{
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							stmt->into->rel->relname)));
+			return NIL;
+		}
+	}
+
 	/* Start building a CreateStmt for creating the target table */
 	create_stmt = makeNode(CreateStmt);
 	create_stmt->relation = relation;
 	create_stmt->islocal = stmt->islocal;
+	create_stmt->if_not_exists = stmt->if_not_exists;
 	into = stmt->into;
 
 	/* Obtain the target list of new table */
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 83c5169430..41e0b35d58 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -6225,10 +6225,11 @@ get_utility_query_def(Query *query, deparse_context *context)
 		bool		istemp = (relation->relpersistence == RELPERSISTENCE_TEMP);
 		bool		isunlogged = (relation->relpersistence == RELPERSISTENCE_UNLOGGED);
 
-		appendStringInfo(buf, "CREATE %s %s %s TABLE ",
+		appendStringInfo(buf, "CREATE %s %s %s TABLE %s ",
 				stmt->islocal ? "LOCAL" : "",
 				istemp ? "TEMP" : "",
-				isunlogged ? "UNLOGGED" : "");
+				isunlogged ? "UNLOGGED" : "",
+				stmt->if_not_exists ? "IF NOT EXISTS " : "");
 
 		if (!istemp && relation->schemaname && relation->schemaname[0])
 			appendStringInfo(buf, "%s.", relation->schemaname);