Fix GC table regex for lower case compatibility (#753)

* Fix GC table regex for lower case compatibility

* gofmt

Author: yushuqin

go/vt/schema/tablegc.go

@@ -52,7 +52,7 @@ func (s TableGCState) TableHint() InternalTableHint {
 }
 
 const (
-	OldGCTableNameExpression string = `^_vt_(HOLD|PURGE|EVAC|DROP)_([0-f]{32})_([0-9]{14})$`
+	OldGCTableNameExpression string = `^_vt_(HOLD|PURGE|EVAC|DROP|hold|purge|evac|drop)_([0-f]{32})_([0-9]{14})$`
 	// GCTableNameExpression parses new internal table name format, e.g. _vt_hld_6ace8bcef73211ea87e9f875a4d24e90_20200915120410_
 	GCTableNameExpression string = `^_vt_(hld|prg|evc|drp)_([0-f]{32})_([0-9]{14})_$`
 )
@@ -72,6 +72,7 @@ func init() {
 	gcStatesTableHints[DropTableGCState] = InternalTableGCDropHint
 	for _, gcState := range []TableGCState{HoldTableGCState, PurgeTableGCState, EvacTableGCState, DropTableGCState} {
 		gcStates[string(gcState)] = gcState
+		gcStates[strings.ToLower(string(gcState))] = gcState
 		gcStates[gcState.TableHint().String()] = gcState
 	}
 }

go/vt/schema/tablegc_test.go

@@ -65,6 +65,11 @@ func TestIsGCTableName(t *testing.T) {
 			"_vt_DROP_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
 			"_vt_HOLD_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
 			"_vt_drp_6ace8bcef73211ea87e9f875a4d24e90_20200915120410_",
+			// Test lowercase variants for lower_case_table_names=1 compatibility
+			"_vt_drop_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
+			"_vt_hold_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
+			"_vt_purge_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
+			"_vt_evac_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
 		}
 		for _, tableName := range names {
 			t.Run(tableName, func(t *testing.T) {
@@ -183,6 +188,31 @@ func TestAnalyzeGCTableName(t *testing.T) {
 			tableName: "_vt_xyz_6ace8bcef73211ea87e9f875a4d24e90_20200915120410_",
 			isGC:      false,
 		},
+		// Test lowercase variants for lower_case_table_names=1 compatibility
+		{
+			tableName: "_vt_drop_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
+			state:     DropTableGCState,
+			t:         baseTime,
+			isGC:      true,
+		},
+		{
+			tableName: "_vt_hold_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
+			state:     HoldTableGCState,
+			t:         baseTime,
+			isGC:      true,
+		},
+		{
+			tableName: "_vt_purge_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
+			state:     PurgeTableGCState,
+			t:         baseTime,
+			isGC:      true,
+		},
+		{
+			tableName: "_vt_evac_6ace8bcef73211ea87e9f875a4d24e90_20200915120410",
+			state:     EvacTableGCState,
+			t:         baseTime,
+			isGC:      true,
+		},
 	}
 	for _, ts := range tt {
 		t.Run(ts.tableName, func(t *testing.T) {