Online DDL: better support for range partitioning

go/test/endtoend/onlineddl/revert/onlineddl_revert_test.go

@@ -1142,7 +1142,7 @@ func testRevert(t *testing.T) {
 		checkPartitionedTableCountRows(t, 6)
 	})
 	t.Run("partitions: drop first partition", func(t *testing.T) {
-		uuid := testOnlineDDLStatementForTable(t, "alter table part_test drop partition `p1`", ddlStrategy+" --fast-range-rotation", "vtgate", "")
+		uuid := testOnlineDDLStatementForTable(t, "alter table part_test drop partition `p1`", ddlStrategy, "vtgate", "")
 		uuids = append(uuids, uuid)
 		onlineddl.CheckMigrationStatus(t, &vtParams, shards, uuid, schema.OnlineDDLStatusComplete)
 		checkTable(t, partitionedTableName, true)
@@ -1157,7 +1157,7 @@ func testRevert(t *testing.T) {
 		checkPartitionedTableCountRows(t, 5)
 	})
 	t.Run("partitions: add new partition", func(t *testing.T) {
-		uuid := testOnlineDDLStatementForTable(t, "alter table part_test add partition (PARTITION p7 VALUES LESS THAN (70))", ddlStrategy+" --fast-range-rotation", "vtgate", "")
+		uuid := testOnlineDDLStatementForTable(t, "alter table part_test add partition (PARTITION p7 VALUES LESS THAN (70))", ddlStrategy, "vtgate", "")
 		uuids = append(uuids, uuid)
 		onlineddl.CheckMigrationStatus(t, &vtParams, shards, uuid, schema.OnlineDDLStatusComplete)
 		checkTable(t, partitionedTableName, true)

go/vt/schema/ddl_strategy.go

@@ -209,7 +209,7 @@ func (setting *DDLStrategySetting) IsPreferInstantDDL() bool {
 
 // IsFastRangeRotationFlag checks if strategy options include --fast-range-rotation
 func (setting *DDLStrategySetting) IsFastRangeRotationFlag() bool {
-	return setting.hasFlag(fastRangeRotationFlag)
+	return true
 }
 
 // isCutOverThresholdFlag returns true when given option denotes a `--cut-over-threshold=[...]` flag
@@ -324,7 +324,7 @@ func (setting *DDLStrategySetting) RuntimeOptions() []string {
 		}
 		switch {
 		case isFlag(opt, declarativeFlag):
-		case isFlag(opt, skipTopoFlag):
+		case isFlag(opt, skipTopoFlag): // deprecated flag, parsed for backwards compatibility
 		case isFlag(opt, singletonFlag):
 		case isFlag(opt, singletonContextFlag):
 		case isFlag(opt, allowZeroInDateFlag):
@@ -333,7 +333,7 @@ func (setting *DDLStrategySetting) RuntimeOptions() []string {
 		case isFlag(opt, inOrderCompletionFlag):
 		case isFlag(opt, allowConcurrentFlag):
 		case isFlag(opt, preferInstantDDL):
-		case isFlag(opt, fastRangeRotationFlag):
+		case isFlag(opt, fastRangeRotationFlag): // deprecated flag, parsed for backwards compatibility
 		case isFlag(opt, vreplicationTestSuite):
 		case isFlag(opt, allowForeignKeysFlag):
 		case isFlag(opt, analyzeTableFlag):

go/vt/schema/ddl_strategy_test.go

@@ -384,7 +384,7 @@ func TestParseDDLStrategy(t *testing.T) {
 			assert.Equal(t, ts.isPostponeLaunch, setting.IsPostponeLaunch())
 			assert.Equal(t, ts.isAllowConcurrent, setting.IsAllowConcurrent())
 			assert.Equal(t, ts.fastOverRevertible, setting.IsPreferInstantDDL())
-			assert.Equal(t, ts.fastRangeRotation, setting.IsFastRangeRotationFlag())
+			assert.True(t, setting.IsFastRangeRotationFlag())
 			assert.Equal(t, ts.allowForeignKeys, setting.IsAllowForeignKeysFlag())
 			assert.Equal(t, ts.analyzeTable, setting.IsAnalyzeTableFlag())
 			cutOverThreshold, err := setting.CutOverThreshold()

go/vt/schemadiff/analysis.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package schemadiff
+
+import "vitess.io/vitess/go/vt/sqlparser"
+
+// AlterTableRotatesRangePartition answers `true` when the given ALTER TABLE statemnts performas any sort
+// of range partition rotation, that is applicable immediately and without moving data.
+// Such would be:
+// - Dropping any partition(s)
+// - Adding a new partition (empty, at the end of the list)
+func AlterTableRotatesRangePartition(alterTable *sqlparser.AlterTable) (bool, error) {
+	spec := alterTable.PartitionSpec
+	if spec == nil {
+		return false, nil
+	}
+	errorResult := func(conflictingNode sqlparser.SQLNode) error {
+		return &PartitionSpecNonExclusiveError{
+			Table:                alterTable.Table.Name.String(),
+			PartitionSpec:        spec,
+			ConflictingStatement: sqlparser.CanonicalString(conflictingNode),
+		}
+	}
+	if len(alterTable.AlterOptions) > 0 {
+		// This should never happen, unless someone programmatically tampered with the AlterTable AST.
+		return false, errorResult(alterTable.AlterOptions[0])
+	}
+	if alterTable.PartitionOption != nil {
+		// This should never happen, unless someone programmatically tampered with the AlterTable AST.
+		return false, errorResult(alterTable.PartitionOption)
+	}
+	switch spec.Action {
+	case sqlparser.AddAction:
+		if len(spec.Definitions) > 1 {
+			// This should never happen, unless someone programmatically tampered with the AlterTable AST.
+			return false, errorResult(spec.Definitions[1])
+		}
+		return true, nil
+	case sqlparser.DropAction:
+		return true, nil
+	default:
+		return false, nil
+	}
+}

go/vt/schemadiff/analysis_test.go

@@ -0,0 +1,74 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package schemadiff
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"vitess.io/vitess/go/vt/sqlparser"
+)
+
+// AnalyzePartitionRotation analyzes a given AlterTable statement to see whether it has partition rotation
+// commands, and if so, is the ALTER TABLE statement valid in MySQL. In MySQL, a single ALTER TABLE statement
+// cannot apply multiple rotation commands, nor can it mix rotation commands with other types of changes.
+func TestAlterTableRotatesRangePartition(t *testing.T) {
+	tcases := []struct {
+		alter  string
+		expect bool
+	}{
+		{
+			alter:  "ALTER TABLE t ADD PARTITION (PARTITION p1 VALUES LESS THAN (10))",
+			expect: true,
+		},
+		{
+			alter:  "ALTER TABLE t DROP PARTITION p1",
+			expect: true,
+		},
+		{
+			alter:  "ALTER TABLE t DROP PARTITION p1, p2",
+			expect: true,
+		},
+		{
+			alter: "ALTER TABLE t TRUNCATE PARTITION p3",
+		},
+		{
+			alter: "ALTER TABLE t COALESCE PARTITION 3",
+		},
+		{
+			alter: "ALTER TABLE t partition by range (id) (partition p1 values less than (10), partition p2 values less than (20), partition p3 values less than (30))",
+		},
+		{
+			alter: "ALTER TABLE t ADD COLUMN c1 INT, DROP COLUMN c2",
+		},
+	}
+
+	for _, tcase := range tcases {
+		t.Run(tcase.alter, func(t *testing.T) {
+			stmt, err := sqlparser.NewTestParser().ParseStrictDDL(tcase.alter)
+			require.NoError(t, err)
+			alterTable, ok := stmt.(*sqlparser.AlterTable)
+			require.True(t, ok)
+
+			result, err := AlterTableRotatesRangePartition(alterTable)
+			require.NoError(t, err)
+			assert.Equal(t, tcase.expect, result)
+		})
+	}
+}

go/vt/schemadiff/errors.go

@@ -22,6 +22,7 @@ import (
 	"strings"
 
 	"vitess.io/vitess/go/sqlescape"
+	"vitess.io/vitess/go/vt/sqlparser"
 )
 
 var (
@@ -468,3 +469,21 @@ func (e *SubsequentDiffRejectedError) Error() string {
 	}
 	return b.String()
 }
+
+// PartitionSpecNonExclusiveError is returned when a partition spec change is found alongside other changes.
+// for example, in MySQL it is invalid to both DROP PARTITION (a partition spec change) and ADD COLUMN
+// in the same ALTER TABLE statement. In fact, even two partition spec changes in the same ALTER TABLE
+// statement are not allowed.
+// This error should never be encountered in normal circumstances, because:
+// - `sqlparser` should not allow such statements to be parsed.
+// - schemadiff's `Diff()` function will never generate a single `ALTER TABLE` statement with such multiple changes.
+// The error is used for integrity checks only, and should be considered a bug if encountered.
+type PartitionSpecNonExclusiveError struct {
+	Table                string
+	PartitionSpec        *sqlparser.PartitionSpec
+	ConflictingStatement string
+}
+
+func (e *PartitionSpecNonExclusiveError) Error() string {
+	return fmt.Sprintf("ALTER TABLE on %s, may only have a single partition spec change, and other changes are not allowed. Found spec: %s; and change: %s", sqlescape.EscapeID(e.Table), sqlparser.CanonicalString(e.PartitionSpec), e.ConflictingStatement)
+}

go/vt/schemadiff/table.go

@@ -19,6 +19,7 @@ package schemadiff
 import (
 	"fmt"
 	"math"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -1203,52 +1204,64 @@ func (c *CreateTableEntity) isRangePartitionsRotation(
 	if t1Partitions.Type != sqlparser.RangeType {
 		return false, nil, nil
 	}
-	definitions1 := t1Partitions.Definitions
+	definitions1 := slices.Clone(t1Partitions.Definitions)
 	definitions2 := t2Partitions.Definitions
-	// there has to be a non-empty shared list, therefore both definitions must be non-empty:
 	if len(definitions1) == 0 {
 		return false, nil, nil
 	}
 	if len(definitions2) == 0 {
 		return false, nil, nil
 	}
+	definitions2map := make(map[string]*sqlparser.PartitionDefinition, len(definitions2))
+	for _, definition := range definitions2 {
+		definitions2map[sqlparser.CanonicalString(definition)] = definition
+	}
+	// Find dropped partitions:
 	var droppedPartitions1 []*sqlparser.PartitionDefinition
-	// It's OK for prefix of t1 partitions to be nonexistent in t2 (as they may have been rotated away in t2)
-	for len(definitions1) > 0 && !sqlparser.Equals.RefOfPartitionDefinition(definitions1[0], definitions2[0]) {
-		droppedPartitions1 = append(droppedPartitions1, definitions1[0])
-		definitions1 = definitions1[1:]
+	for i := len(definitions1) - 1; i >= 0; i-- {
+		definition := definitions1[i]
+		if _, ok := definitions2map[sqlparser.CanonicalString(definition)]; !ok {
+			// In range partitioning, it's allowed to drop any partition, whether it's the first, somewhere in the middle, or last.
+			droppedPartitions1 = append(droppedPartitions1, definition)
+			// We remove the definition from the list, so that we can then compare the remaining definitions
+			definitions1 = append(definitions1[:i], definitions1[i+1:]...)
+		}
 	}
+	slices.Reverse(droppedPartitions1)
 	if len(definitions1) == 0 {
-		// We've exhausted definition1 trying to find a shared partition with definitions2. Nothing found.
-		// so there is no shared sequence between the two tables.
+		// Nothing shared between the two partition lists.
 		return false, nil, nil
 	}
+	// In range partitioning, it's only allowed to ADD one partition at the end of the range.
+	// We allow multiple here, and the diff mechanism will later split them to subsequent diffs.
+
+	// Let's now validate that any added partitions in t2Partitions are strictly a suffix of t1Partitions
 	if len(definitions1) > len(definitions2) {
 		return false, nil, nil
 	}
-	// To save computation, and because we've already shown that sqlparser.EqualsRefOfPartitionDefinition(definitions1[0], definitions2[0]), nil,
-	// we can skip one element
-	definitions1 = definitions1[1:]
-	definitions2 = definitions2[1:]
-	// Now let's ensure that whatever is remaining in definitions1 is an exact match for a prefix of definitions2
-	// It's ok if we end up with leftover elements in definition2
-	for len(definitions1) > 0 {
-		if !sqlparser.Equals.RefOfPartitionDefinition(definitions1[0], definitions2[0]) {
+	for i := range definitions1 {
+		if !sqlparser.Equals.RefOfPartitionDefinition(definitions1[i], definitions2[i]) {
+			// Not a suffix
 			return false, nil, nil
 		}
-		definitions1 = definitions1[1:]
-		definitions2 = definitions2[1:]
 	}
-	addedPartitions2 := definitions2
-	partitionSpecs := make([]*sqlparser.PartitionSpec, 0, len(droppedPartitions1)+len(addedPartitions2))
-	for _, p := range droppedPartitions1 {
+	// And the suffix is any remaining definitions
+	addedPartitions2 := definitions2[len(definitions1):]
+
+	var partitionSpecs []*sqlparser.PartitionSpec
+	// Dropped partitions:
+	if len(droppedPartitions1) > 0 {
+		// A single DROP PARTITION clause can specify multiple partition names
 		partitionSpec := &sqlparser.PartitionSpec{
 			Action: sqlparser.DropAction,
-			Names:  []sqlparser.IdentifierCI{p.Name},
+		}
+		for _, p := range droppedPartitions1 {
+			partitionSpec.Names = append(partitionSpec.Names, p.Name)
+			annotations.MarkRemoved(sqlparser.CanonicalString(p))
 		}
 		partitionSpecs = append(partitionSpecs, partitionSpec)
-		annotations.MarkRemoved(sqlparser.CanonicalString(p))
 	}
+	// Added partitions:
 	for _, p := range addedPartitions2 {
 		partitionSpec := &sqlparser.PartitionSpec{
 			Action:      sqlparser.AddAction,