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mvcc_index_merger.go
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mvcc_index_merger.go
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// Copyright 2021 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.
package backfill
import (
"context"
"time"
"github.com/cockroachdb/cockroach/pkg/base"
"github.com/cockroachdb/cockroach/pkg/keys"
"github.com/cockroachdb/cockroach/pkg/kv"
"github.com/cockroachdb/cockroach/pkg/kv/kvpb"
"github.com/cockroachdb/cockroach/pkg/roachpb"
"github.com/cockroachdb/cockroach/pkg/settings"
"github.com/cockroachdb/cockroach/pkg/sql/catalog"
"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
"github.com/cockroachdb/cockroach/pkg/sql/catalog/tabledesc"
"github.com/cockroachdb/cockroach/pkg/sql/execinfra"
"github.com/cockroachdb/cockroach/pkg/sql/execinfrapb"
"github.com/cockroachdb/cockroach/pkg/sql/isql"
"github.com/cockroachdb/cockroach/pkg/sql/rowenc"
"github.com/cockroachdb/cockroach/pkg/sql/sem/eval"
"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
"github.com/cockroachdb/cockroach/pkg/sql/types"
"github.com/cockroachdb/cockroach/pkg/util/admission/admissionpb"
"github.com/cockroachdb/cockroach/pkg/util/ctxgroup"
"github.com/cockroachdb/cockroach/pkg/util/hlc"
"github.com/cockroachdb/cockroach/pkg/util/log"
"github.com/cockroachdb/cockroach/pkg/util/mon"
"github.com/cockroachdb/cockroach/pkg/util/syncutil"
"github.com/cockroachdb/errors"
"github.com/cockroachdb/logtags"
)
// indexBackfillMergeBatchSize is the maximum number of rows we attempt to merge
// in a single transaction during the merging process.
var indexBackfillMergeBatchSize = settings.RegisterIntSetting(
settings.ApplicationLevel,
"bulkio.index_backfill.merge_batch_size",
"the number of rows we merge between temporary and adding indexes in a single batch",
1000,
settings.NonNegativeInt, /* validateFn */
)
// indexBackfillMergeBatchBytes is the maximum number of bytes we attempt to
// merge from the temporary index in a single transaction during the merging
// process.
var indexBackfillMergeBatchBytes = settings.RegisterIntSetting(
settings.ApplicationLevel,
"bulkio.index_backfill.merge_batch_bytes",
"the max number of bytes we merge between temporary and adding indexes in a single batch",
16<<20,
settings.NonNegativeInt,
)
// indexBackfillMergeNumWorkers is the number of parallel merges per node in the
// cluster used for the merge step of the index backfill. It is currently
// default to 4 as higher values didn't seem to improve the index build times in
// the schemachange/index/tpcc/w=1000 roachtest.
var indexBackfillMergeNumWorkers = settings.RegisterIntSetting(
settings.ApplicationLevel,
"bulkio.index_backfill.merge_num_workers",
"the number of parallel merges per node in the cluster",
4,
settings.PositiveInt,
)
// IndexBackfillMerger is a processor that merges entries from the corresponding
// temporary index to a new index.
type IndexBackfillMerger struct {
processorID int32
spec execinfrapb.IndexBackfillMergerSpec
desc catalog.TableDescriptor
out execinfra.ProcOutputHelper
flowCtx *execinfra.FlowCtx
evalCtx *eval.Context
mon *mon.BytesMonitor
muBoundAccount muBoundAccount
}
// OutputTypes is always nil.
func (ibm *IndexBackfillMerger) OutputTypes() []*types.T {
return nil
}
// MustBeStreaming is always false.
func (ibm *IndexBackfillMerger) MustBeStreaming() bool {
return false
}
const indexBackfillMergeProgressReportInterval = 10 * time.Second
// Run runs the processor.
func (ibm *IndexBackfillMerger) Run(ctx context.Context, output execinfra.RowReceiver) {
opName := "IndexBackfillMerger"
ctx = logtags.AddTag(ctx, opName, int(ibm.spec.Table.ID))
ctx, span := execinfra.ProcessorSpan(ctx, ibm.flowCtx, opName, ibm.processorID)
defer span.Finish()
defer output.ProducerDone()
defer execinfra.SendTraceData(ctx, ibm.flowCtx, output)
mu := struct {
syncutil.Mutex
completedSpans []roachpb.Span
completedSpanIdx []int32
}{}
storeChunkProgress := func(chunk mergeChunk) {
mu.Lock()
defer mu.Unlock()
mu.completedSpans = append(mu.completedSpans, chunk.completedSpan)
mu.completedSpanIdx = append(mu.completedSpanIdx, chunk.spanIdx)
}
getStoredProgressForPush := func() execinfrapb.RemoteProducerMetadata_BulkProcessorProgress {
var prog execinfrapb.RemoteProducerMetadata_BulkProcessorProgress
mu.Lock()
defer mu.Unlock()
prog.CompletedSpans = append(prog.CompletedSpans, mu.completedSpans...)
prog.CompletedSpanIdx = append(prog.CompletedSpanIdx, mu.completedSpanIdx...)
mu.completedSpans, mu.completedSpanIdx = nil, nil
return prog
}
var outputMu syncutil.Mutex
pushProgress := func() {
p := getStoredProgressForPush()
if p.CompletedSpans != nil {
log.VEventf(ctx, 2, "sending coordinator completed spans: %+v", p.CompletedSpans)
}
// Even though the contract of execinfra.RowReceiver says that Push is
// thread-safe, in reality it's not always the case, so we protect it
// with a mutex. At the time of writing, the only source of concurrency
// for Push()ing is present due to testing knobs though.
outputMu.Lock()
defer outputMu.Unlock()
output.Push(nil, &execinfrapb.ProducerMetadata{BulkProcessorProgress: &p})
}
semaCtx := tree.MakeSemaContext()
if err := ibm.out.Init(ctx, &execinfrapb.PostProcessSpec{}, nil, &semaCtx, ibm.flowCtx.NewEvalCtx()); err != nil {
output.Push(nil, &execinfrapb.ProducerMetadata{Err: err})
return
}
numWorkers := int(indexBackfillMergeNumWorkers.Get(&ibm.evalCtx.Settings.SV))
mergeCh := make(chan mergeChunk)
mergeTimestamp := ibm.spec.MergeTimestamp
g := ctxgroup.WithContext(ctx)
runWorker := func(ctx context.Context) error {
for mergeChunk := range mergeCh {
err := ibm.merge(ctx, ibm.evalCtx.Codec, ibm.desc, ibm.spec.TemporaryIndexes[mergeChunk.spanIdx],
ibm.spec.AddedIndexes[mergeChunk.spanIdx], mergeChunk.keys, mergeChunk.completedSpan)
if err != nil {
return err
}
storeChunkProgress(mergeChunk)
// After the keys have been merged, we can free the memory used by the
// chunk.
mergeChunk.keys = nil
ibm.shrinkBoundAccount(ctx, mergeChunk.memUsed)
if knobs, ok := ibm.flowCtx.Cfg.TestingKnobs.IndexBackfillMergerTestingKnobs.(*IndexBackfillMergerTestingKnobs); ok {
if knobs != nil {
if knobs.PushesProgressEveryChunk {
pushProgress()
}
if knobs.RunAfterMergeChunk != nil {
knobs.RunAfterMergeChunk()
}
}
}
}
return nil
}
for worker := 0; worker < numWorkers; worker++ {
g.GoCtx(runWorker)
}
g.GoCtx(func(ctx context.Context) error {
defer close(mergeCh)
for i := range ibm.spec.Spans {
sp := ibm.spec.Spans[i]
idx := ibm.spec.SpanIdx[i]
key := sp.Key
for key != nil {
chunk, nextKey, err := ibm.scan(ctx, idx, key, sp.EndKey, mergeTimestamp)
if err != nil {
return err
}
select {
case <-ctx.Done():
return ctx.Err()
case mergeCh <- chunk:
}
key = nextKey
if knobs, ok := ibm.flowCtx.Cfg.TestingKnobs.IndexBackfillMergerTestingKnobs.(*IndexBackfillMergerTestingKnobs); ok {
if knobs != nil && knobs.RunAfterScanChunk != nil {
knobs.RunAfterScanChunk()
}
}
}
}
return nil
})
workersDoneCh := make(chan error)
go func() { workersDoneCh <- g.Wait() }()
tick := time.NewTicker(indexBackfillMergeProgressReportInterval)
defer tick.Stop()
var err error
for {
select {
case <-tick.C:
pushProgress()
case err = <-workersDoneCh:
if err != nil {
output.Push(nil, &execinfrapb.ProducerMetadata{Err: err})
}
return
}
}
}
var _ execinfra.Processor = &IndexBackfillMerger{}
type mergeChunk struct {
completedSpan roachpb.Span
keys []roachpb.Key
spanIdx int32
memUsed int64
}
func (ibm *IndexBackfillMerger) scan(
ctx context.Context,
spanIdx int32,
startKey roachpb.Key,
endKey roachpb.Key,
readAsOf hlc.Timestamp,
) (mergeChunk, roachpb.Key, error) {
if knobs, ok := ibm.flowCtx.Cfg.TestingKnobs.IndexBackfillMergerTestingKnobs.(*IndexBackfillMergerTestingKnobs); ok {
if knobs != nil && knobs.RunBeforeScanChunk != nil {
if err := knobs.RunBeforeScanChunk(startKey); err != nil {
return mergeChunk{}, nil, err
}
}
}
chunkSize := indexBackfillMergeBatchSize.Get(&ibm.evalCtx.Settings.SV)
chunkBytes := indexBackfillMergeBatchBytes.Get(&ibm.evalCtx.Settings.SV)
var br *kvpb.BatchResponse
if err := ibm.flowCtx.Cfg.DB.Txn(ctx, func(ctx context.Context, txn isql.Txn) error {
if err := txn.KV().SetFixedTimestamp(ctx, readAsOf); err != nil {
return err
}
// For now just grab all of the destination KVs and merge the corresponding entries.
log.VInfof(ctx, 2, "scanning batch [%s, %s) at %v to merge", startKey, endKey, readAsOf)
ba := &kvpb.BatchRequest{}
ba.TargetBytes = chunkBytes
if err := ibm.growBoundAccount(ctx, chunkBytes); err != nil {
return errors.Wrap(err, "failed to fetch keys to merge from temp index")
}
defer ibm.shrinkBoundAccount(ctx, chunkBytes)
ba.MaxSpanRequestKeys = chunkSize
ba.Add(&kvpb.ScanRequest{
RequestHeader: kvpb.RequestHeader{
Key: startKey,
EndKey: endKey,
},
ScanFormat: kvpb.KEY_VALUES,
})
var pErr *kvpb.Error
br, pErr = txn.KV().Send(ctx, ba)
if pErr != nil {
return pErr.GoError()
}
return nil
}, isql.WithPriority(admissionpb.BulkNormalPri)); err != nil {
return mergeChunk{}, nil, err
}
resp := br.Responses[0].GetScan()
chunk := mergeChunk{
spanIdx: spanIdx,
}
var chunkMem int64
if len(resp.Rows) > 0 {
if err := func() error {
ibm.muBoundAccount.Lock()
defer ibm.muBoundAccount.Unlock()
for i := range resp.Rows {
chunk.keys = append(chunk.keys, resp.Rows[i].Key)
if err := ibm.muBoundAccount.boundAccount.Grow(ctx, int64(len(resp.Rows[i].Key))); err != nil {
return errors.Wrap(err, "failed to allocate space for merge keys")
}
chunkMem += int64(len(resp.Rows[i].Key))
}
return nil
}(); err != nil {
return mergeChunk{}, nil, err
}
}
chunk.memUsed = chunkMem
var nextStart roachpb.Key
if resp.ResumeSpan == nil {
chunk.completedSpan = roachpb.Span{Key: startKey, EndKey: endKey}
} else {
nextStart = resp.ResumeSpan.Key
chunk.completedSpan = roachpb.Span{Key: startKey, EndKey: nextStart}
}
return chunk, nextStart, nil
}
// merge merges the latest values for sourceKeys from the index with sourceID
// into the index with destinationID.
func (ibm *IndexBackfillMerger) merge(
ctx context.Context,
codec keys.SQLCodec,
table catalog.TableDescriptor,
sourceID descpb.IndexID,
destinationID descpb.IndexID,
sourceKeys []roachpb.Key,
sourceSpan roachpb.Span,
) error {
sourcePrefix := rowenc.MakeIndexKeyPrefix(codec, table.GetID(), sourceID)
destPrefix := rowenc.MakeIndexKeyPrefix(codec, table.GetID(), destinationID)
err := ibm.flowCtx.Cfg.DB.Txn(ctx, func(
ctx context.Context, txn isql.Txn,
) error {
var deletedCount int
txn.KV().AddCommitTrigger(func(ctx context.Context) {
commitTs, _ := txn.KV().CommitTimestamp()
log.VInfof(ctx, 2, "merged batch of %d keys (%d deletes) (span: %s) (commit timestamp: %s)",
len(sourceKeys),
deletedCount,
sourceSpan,
commitTs,
)
})
if len(sourceKeys) == 0 {
return nil
}
wb, memUsedInMerge, deletedKeys, err := ibm.constructMergeBatch(
ctx, txn.KV(), sourceKeys, sourcePrefix, destPrefix,
)
if err != nil {
return err
}
defer ibm.shrinkBoundAccount(ctx, memUsedInMerge)
deletedCount = deletedKeys
if err := txn.KV().Run(ctx, wb); err != nil {
return err
}
if knobs, ok := ibm.flowCtx.Cfg.TestingKnobs.IndexBackfillMergerTestingKnobs.(*IndexBackfillMergerTestingKnobs); ok {
if knobs != nil && knobs.RunDuringMergeTxn != nil {
if err := knobs.RunDuringMergeTxn(ctx, txn.KV(), sourceSpan.Key, sourceSpan.EndKey); err != nil {
return err
}
}
}
return nil
})
return err
}
func (ibm *IndexBackfillMerger) constructMergeBatch(
ctx context.Context,
txn *kv.Txn,
sourceKeys []roachpb.Key,
sourcePrefix []byte,
destPrefix []byte,
) (*kv.Batch, int64, int, error) {
rb := txn.NewBatch()
for i := range sourceKeys {
rb.Get(sourceKeys[i])
}
if err := txn.Run(ctx, rb); err != nil {
return nil, 0, 0, err
}
// We acquire the bound account lock for the entirety of the merge batch
// construction so that we don't have to acquire the lock every time we want
// to grow the account.
var memUsedInMerge int64
ibm.muBoundAccount.Lock()
defer ibm.muBoundAccount.Unlock()
for i := range rb.Results {
// Since the source index is delete-preserving, reading the latest value for
// a key that has existed in the past should always return a value.
if rb.Results[i].Rows[0].Value == nil {
return nil, 0, 0, errors.AssertionFailedf("expected value to be present in temp index for key=%s", rb.Results[i].Rows[0].Key)
}
rowMem := int64(len(rb.Results[i].Rows[0].Key)) + int64(len(rb.Results[i].Rows[0].Value.RawBytes))
if err := ibm.muBoundAccount.boundAccount.Grow(ctx, rowMem); err != nil {
return nil, 0, 0, errors.Wrap(err, "failed to allocate space to read latest keys from temp index")
}
memUsedInMerge += rowMem
}
prefixLen := len(sourcePrefix)
destKey := make([]byte, len(destPrefix))
var deletedCount int
wb := txn.NewBatch()
for i := range rb.Results {
sourceKV := &rb.Results[i].Rows[0]
if len(sourceKV.Key) < prefixLen {
return nil, 0, 0, errors.Errorf("key for index entry %v does not start with prefix %v", sourceKV, sourcePrefix)
}
destKey = destKey[:0]
destKey = append(destKey, destPrefix...)
destKey = append(destKey, sourceKV.Key[prefixLen:]...)
mergedEntry, deleted, err := mergeEntry(sourceKV, destKey)
if err != nil {
return nil, 0, 0, err
}
entryBytes := mergedEntryBytes(mergedEntry, deleted)
if err := ibm.muBoundAccount.boundAccount.Grow(ctx, entryBytes); err != nil {
return nil, 0, 0, errors.Wrap(err, "failed to allocate space to merge entry from temp index")
}
memUsedInMerge += entryBytes
if deleted {
deletedCount++
wb.Del(mergedEntry.Key)
} else {
wb.Put(mergedEntry.Key, mergedEntry.Value)
}
}
return wb, memUsedInMerge, deletedCount, nil
}
func mergedEntryBytes(entry *kv.KeyValue, deleted bool) int64 {
if deleted {
return int64(len(entry.Key))
}
return int64(len(entry.Key) + len(entry.Value.RawBytes))
}
func mergeEntry(sourceKV *kv.KeyValue, destKey roachpb.Key) (*kv.KeyValue, bool, error) {
var destTagAndData []byte
var deleted bool
tempWrapper, err := rowenc.DecodeWrapper(sourceKV.Value)
if err != nil {
return nil, false, err
}
if tempWrapper.Deleted {
deleted = true
} else {
destTagAndData = tempWrapper.Value
}
value := &roachpb.Value{}
value.SetTagAndData(destTagAndData)
return &kv.KeyValue{
Key: destKey.Clone(),
Value: value,
}, deleted, nil
}
func (ibm *IndexBackfillMerger) growBoundAccount(ctx context.Context, growBy int64) error {
ibm.muBoundAccount.Lock()
defer ibm.muBoundAccount.Unlock()
return ibm.muBoundAccount.boundAccount.Grow(ctx, growBy)
}
func (ibm *IndexBackfillMerger) shrinkBoundAccount(ctx context.Context, shrinkBy int64) {
ibm.muBoundAccount.Lock()
defer ibm.muBoundAccount.Unlock()
ibm.muBoundAccount.boundAccount.Shrink(ctx, shrinkBy)
}
// Resume is part of the execinfra.Processor interface.
func (ibm *IndexBackfillMerger) Resume(output execinfra.RowReceiver) {
panic("not implemented")
}
// NewIndexBackfillMerger creates a new IndexBackfillMerger.
func NewIndexBackfillMerger(
ctx context.Context,
flowCtx *execinfra.FlowCtx,
processorID int32,
spec execinfrapb.IndexBackfillMergerSpec,
) (*IndexBackfillMerger, error) {
mergerMon := execinfra.NewMonitor(ctx, flowCtx.Cfg.BackfillerMonitor,
"index-backfiller-merger-mon")
ibm := &IndexBackfillMerger{
processorID: processorID,
spec: spec,
desc: tabledesc.NewUnsafeImmutable(&spec.Table),
flowCtx: flowCtx,
evalCtx: flowCtx.NewEvalCtx(),
mon: mergerMon,
}
ibm.muBoundAccount.boundAccount = mergerMon.MakeBoundAccount()
return ibm, nil
}
// IndexBackfillMergerTestingKnobs is for testing the distributed processors for
// the index backfill merge step.
type IndexBackfillMergerTestingKnobs struct {
// RunBeforeScanChunk is called once before the scan of each chunk. It is
// called with starting key of the chunk.
RunBeforeScanChunk func(startKey roachpb.Key) error
// RunAfterScanChunk is called once after a chunk has been successfully scanned.
RunAfterScanChunk func()
RunDuringMergeTxn func(ctx context.Context, txn *kv.Txn, startKey roachpb.Key, endKey roachpb.Key) error
// PushesProgressEveryChunk forces the process to push the merge process after
// every chunk.
PushesProgressEveryChunk bool
// RunAfterMergeChunk is called once after a chunk has been successfully merged.
RunAfterMergeChunk func()
}
var _ base.ModuleTestingKnobs = &IndexBackfillMergerTestingKnobs{}
// ModuleTestingKnobs implements the base.ModuleTestingKnobs interface.
func (*IndexBackfillMergerTestingKnobs) ModuleTestingKnobs() {}