ddl: forbid create Generated column with Grouping function (#49930)…

… (#51094)

close #49909

pkg/ddl/generated_column.go

@@ -289,6 +289,11 @@ type illegalFunctionChecker struct {
 func (c *illegalFunctionChecker) Enter(inNode ast.Node) (outNode ast.Node, skipChildren bool) {
 	switch node := inNode.(type) {
 	case *ast.FuncCallExpr:
+		// Grouping function is not allowed, issue #49909.
+		if node.FnName.L == ast.Grouping {
+			c.hasAggFunc = true
+			return inNode, true
+		}
 		// Blocked functions & non-builtin functions is not allowed
 		_, isFunctionBlocked := expression.IllegalFunctions4GeneratedColumns[node.FnName.L]
 		if isFunctionBlocked || !expression.IsFunctionSupported(node.FnName.L) {

tests/integrationtest/r/ddl/db_integration.result

@@ -1223,3 +1223,10 @@ alter table t reorganize partition p0 into (partition p01 values less than (10),
 show warnings;
 Level	Code	Message
 Warning	1105	The statistics of related partitions will be outdated after reorganizing partitions. Please use 'ANALYZE TABLE' statement if you want to update it now
+drop table if exists t;
+create table t(a int, b int as ((grouping(a))) stored);
+Error 1111 (HY000): Invalid use of group function
+create table t(a int);
+alter table t add column  b int as ((grouping(a))) stored;
+Error 1111 (HY000): Invalid use of group function
+drop table t;

tests/integrationtest/t/ddl/db_integration.test

@@ -1026,3 +1026,11 @@ create table t (id bigint, b varchar(20), index idxb(b)) partition by range(id)
 alter table t reorganize partition p0 into (partition p01 values less than (10), partition p02 values less than (20));
 show warnings;
 
+# Test Generated column use Grouping function, issue #49909.
+drop table if exists t;
+--error 1111
+create table t(a int, b int as ((grouping(a))) stored);
+create table t(a int);
+--error 1111
+alter table t add column  b int as ((grouping(a))) stored;
+drop table t;