Force index in unique key range queries (#1237)

* WIP

* Pass entire sql.UniqueKey

* newline for limit

* Rename var

---------

Co-authored-by: meiji163 <[email protected]>

Author: timvaillancourt

go/logic/applier.go

@@ -471,7 +471,7 @@ func (this *Applier) ExecuteThrottleQuery() (int64, error) {
 // readMigrationMinValues returns the minimum values to be iterated on rowcopy
 func (this *Applier) readMigrationMinValues(tx *gosql.Tx, uniqueKey *sql.UniqueKey) error {
 	this.migrationContext.Log.Debugf("Reading migration range according to key: %s", uniqueKey.Name)
-	query, err := sql.BuildUniqueKeyMinValuesPreparedQuery(this.migrationContext.DatabaseName, this.migrationContext.OriginalTableName, &uniqueKey.Columns)
+	query, err := sql.BuildUniqueKeyMinValuesPreparedQuery(this.migrationContext.DatabaseName, this.migrationContext.OriginalTableName, uniqueKey)
 	if err != nil {
 		return err
 	}
@@ -496,7 +496,7 @@ func (this *Applier) readMigrationMinValues(tx *gosql.Tx, uniqueKey *sql.UniqueK
 // readMigrationMaxValues returns the maximum values to be iterated on rowcopy
 func (this *Applier) readMigrationMaxValues(tx *gosql.Tx, uniqueKey *sql.UniqueKey) error {
 	this.migrationContext.Log.Debugf("Reading migration range according to key: %s", uniqueKey.Name)
-	query, err := sql.BuildUniqueKeyMaxValuesPreparedQuery(this.migrationContext.DatabaseName, this.migrationContext.OriginalTableName, &uniqueKey.Columns)
+	query, err := sql.BuildUniqueKeyMaxValuesPreparedQuery(this.migrationContext.DatabaseName, this.migrationContext.OriginalTableName, uniqueKey)
 	if err != nil {
 		return err
 	}

go/sql/builder.go

@@ -352,24 +352,24 @@ func BuildUniqueKeyRangeEndPreparedQueryViaTemptable(databaseName, tableName str
 	return result, explodedArgs, nil
 }
 
-func BuildUniqueKeyMinValuesPreparedQuery(databaseName, tableName string, uniqueKeyColumns *ColumnList) (string, error) {
-	return buildUniqueKeyMinMaxValuesPreparedQuery(databaseName, tableName, uniqueKeyColumns, "asc")
+func BuildUniqueKeyMinValuesPreparedQuery(databaseName, tableName string, uniqueKey *UniqueKey) (string, error) {
+	return buildUniqueKeyMinMaxValuesPreparedQuery(databaseName, tableName, uniqueKey, "asc")
 }
 
-func BuildUniqueKeyMaxValuesPreparedQuery(databaseName, tableName string, uniqueKeyColumns *ColumnList) (string, error) {
-	return buildUniqueKeyMinMaxValuesPreparedQuery(databaseName, tableName, uniqueKeyColumns, "desc")
+func BuildUniqueKeyMaxValuesPreparedQuery(databaseName, tableName string, uniqueKey *UniqueKey) (string, error) {
+	return buildUniqueKeyMinMaxValuesPreparedQuery(databaseName, tableName, uniqueKey, "desc")
 }
 
-func buildUniqueKeyMinMaxValuesPreparedQuery(databaseName, tableName string, uniqueKeyColumns *ColumnList, order string) (string, error) {
-	if uniqueKeyColumns.Len() == 0 {
+func buildUniqueKeyMinMaxValuesPreparedQuery(databaseName, tableName string, uniqueKey *UniqueKey, order string) (string, error) {
+	if uniqueKey.Columns.Len() == 0 {
 		return "", fmt.Errorf("Got 0 columns in BuildUniqueKeyMinMaxValuesPreparedQuery")
 	}
 	databaseName = EscapeName(databaseName)
 	tableName = EscapeName(tableName)
 
-	uniqueKeyColumnNames := duplicateNames(uniqueKeyColumns.Names())
+	uniqueKeyColumnNames := duplicateNames(uniqueKey.Columns.Names())
 	uniqueKeyColumnOrder := make([]string, len(uniqueKeyColumnNames))
-	for i, column := range uniqueKeyColumns.Columns() {
+	for i, column := range uniqueKey.Columns.Columns() {
 		uniqueKeyColumnNames[i] = EscapeName(uniqueKeyColumnNames[i])
 		if column.Type == EnumColumnType {
 			uniqueKeyColumnOrder[i] = fmt.Sprintf("concat(%s) %s", uniqueKeyColumnNames[i], order)
@@ -378,14 +378,15 @@ func buildUniqueKeyMinMaxValuesPreparedQuery(databaseName, tableName string, uni
 		}
 	}
 	query := fmt.Sprintf(`
-      select /* gh-ost %s.%s */ %s
-				from
-					%s.%s
-				order by
-					%s
-				limit 1
-    `, databaseName, tableName, strings.Join(uniqueKeyColumnNames, ", "),
-		databaseName, tableName,
+		select /* gh-ost %s.%s */ %s
+			from
+				%s.%s
+			force index (%s)
+			order by %s
+			limit 1
+		`,
+		databaseName, tableName, strings.Join(uniqueKeyColumnNames, ", "),
+		databaseName, tableName, uniqueKey.Name,
 		strings.Join(uniqueKeyColumnOrder, ", "),
 	)
 	return query, nil

go/sql/builder_test.go

@@ -1,5 +1,5 @@
 /*
-   Copyright 2016 GitHub Inc.
+   Copyright 2022 GitHub Inc.
 	 See https://github.com/github/gh-ost/blob/master/LICENSE
 */
 
@@ -310,26 +310,29 @@ func TestBuildUniqueKeyMinValuesPreparedQuery(t *testing.T) {
 	databaseName := "mydb"
 	originalTableName := "tbl"
 	uniqueKeyColumns := NewColumnList([]string{"name", "position"})
+	uniqueKey := &UniqueKey{Name: "PRIMARY", Columns: *uniqueKeyColumns}
 	{
-		query, err := BuildUniqueKeyMinValuesPreparedQuery(databaseName, originalTableName, uniqueKeyColumns)
+		query, err := BuildUniqueKeyMinValuesPreparedQuery(databaseName, originalTableName, uniqueKey)
 		test.S(t).ExpectNil(err)
 		expected := `
 			select /* gh-ost mydb.tbl */ name, position
 			  from
 			    mydb.tbl
+			  force index (PRIMARY)
 			  order by
 			    name asc, position asc
 			  limit 1
 		`
 		test.S(t).ExpectEquals(normalizeQuery(query), normalizeQuery(expected))
 	}
 	{
-		query, err := BuildUniqueKeyMaxValuesPreparedQuery(databaseName, originalTableName, uniqueKeyColumns)
+		query, err := BuildUniqueKeyMaxValuesPreparedQuery(databaseName, originalTableName, uniqueKey)
 		test.S(t).ExpectNil(err)
 		expected := `
 			select /* gh-ost mydb.tbl */ name, position
 			  from
 			    mydb.tbl
+			  force index (PRIMARY)
 			  order by
 			    name desc, position desc
 			  limit 1