executor: improve wide table insert & update performance #7935

lysu · 2018-10-17T12:25:35Z

What problem does this PR solve?

from one of our customers, wide table's INSERT in 2.1 is slower than 2.0

the question is evalRow call chunk.MutRowFromDatums values-len x column-num times, and MutRowFromDatums will make heavy alloc operation

this is cpu pprof result in 58 column insert under dead loop

What is changed and how it works?

eval buffer can be reuse and modify partly(if x = 3, y = x + 1 situation)

Check List

Tests

Unit test
Manual test compare to old code

single thread dead loop to execute a sql insert into 58 columns table and monitor insertValues#insertRows time.

before this PR:

====> 13.343243ms
====> 13.249525ms
====> 12.252023ms
====> 21.257291ms
====> 19.790786ms
====> 12.445035ms
====> 23.729567ms
====> 11.301022ms
====> 12.192163ms
====> 12.253682ms
====> 11.215405ms
====> 11.362502ms

after this PR:

----> 579.105µs
----> 589.978µs
----> 647.785µs
----> 1.184076ms
----> 678.121µs
----> 1.005605ms
----> 565.764µs
----> 617.942µs
----> 628.033µs
----> 569.044µs
----> 575.293µs
----> 605.097µs
----> 569.361µs
----> 935.86µs

Code changes

impl change

Side effects

no

Related changes

Need to cherry-pick to 2.1
Need to be included in the release note

Other Question

MutRowFromDatums is devil, we should avoid to use it and delete other usage too

This change is

lysu · 2018-10-17T12:29:57Z

/run-all-tests

jackysp

LGTM

ngaut · 2018-10-18T03:41:25Z

Please add a performance test to integrate tests.

lysu · 2018-10-18T09:00:55Z

There are some bugs in first version modification.

it works well if expr is const or some expression that doesn't do unsafe operation on chunk.

but when expr is sth like column will meet data corruption, eval will unsafe reuse evalBuffer memory and update wrong data.

so Now, we add Flag() method to expression(use flag because it maybe can provide more information like strickness in furtue) and builtinFunc to indicate whelther we can safe reuse chunk....

the prefect way is modify all builtinFunc impl flag, but it's too much work to do, so now just modify baseBuilitnFuc as

a expression is not reuse chunk memory if all it's children doesn't reuse chunk memory

so, after this PR, sql like insert t values ('1', 2, 2, now()) or update t set a = 1, b =2 where id =1 will be better, but sql like update t1, t2 set t1.v = t2.v where t1.id = t2.id will do like old code.

@zz-jason @tiancaiamao PTAL

tiancaiamao · 2018-10-19T03:31:12Z

executor/insert_common.go

@@ -216,6 +240,13 @@ func (e *InsertValues) evalRow(cols []*table.Column, list []expression.Expressio

 		offset := cols[i].Offset
 		row[offset], hasValue[offset] = val1, true
+		if expr.Flag()&expression.FlagChunkReused > 0 {


The FlagChunkReused makes me confused, if the expression have a reuse flag, than we create a new chunk ?

yes, expression reuse chunk, so we can not reuse old chunk for following eval~

How about expression.HoldChunkMemory, it the returned result of an expression need to hold the memory of the chunk, we need to allocate a new chunk.

expression/builtin.go

zz-jason · 2018-10-20T13:19:16Z

executor/insert_common.go

+	if e.evalBuffer != nil {
+		return
+	}
+	tpsLen := len(e.Table.Cols())


how about s/tpsLen/numCols/

zz-jason · 2018-10-20T13:20:41Z

executor/insert_common.go

+	if e.hasExtraHandle {
+		e.evalBufferTypes[len(e.evalBufferTypes)-1] = types.NewFieldType(mysql.TypeLonglong)
+	}
+	mutChunk := chunk.MutRowFromTypes(e.evalBufferTypes)


how about s/mutChunk/mutRow/

zz-jason · 2018-10-20T13:26:01Z

expression/expression.go

+
+const (
+	// FlagHoldChunkMemory indicates expression return result maybe returned by unsafe operation over chunk.
+	FlagHoldChunkMemory Flag = 1 << iota


By default, this is true. I think we can remove this flag and the Flag() API from the expression interface.

after macro bench, always copy result in insert_rows is

1.059124ms 1.113391ms 1.037529ms 1.018771ms 998.436µs 1.010835ms 929.046µs 1.502075ms 972.367µs 984.169µs 990.929µs 967.04µs 1.797491ms 1.506823ms 957.703µs 979.513µs 1.001699ms 1.062672ms

it's litte differ to not-copy-flag solution, so we choose always copy now

PTAL @tiancaiamao @zz-jason

zz-jason · 2018-10-22T12:45:17Z

expression/column.go

@@ -47,7 +47,7 @@ func (col *CorrelatedColumn) Eval(row chunk.Row) (types.Datum, error) {
 }

 // EvalInt returns int representation of CorrelatedColumn.
-func (col *CorrelatedColumn) EvalInt(ctx sessionctx.Context, row chunk.Row) (int64, bool, error) {
+func (col *CorrelatedColumn) EvalInt(ctx sessionctx.Context, _ chunk.Row) (int64, bool, error) {


the change of this file is irrelevant, can we revert it back?

zz-jason · 2018-10-22T12:51:33Z

executor/update.go

@@ -141,6 +142,8 @@ func (e *UpdateExec) fetchChunkRows(ctx context.Context) error {
 	fields := e.children[0].retTypes()
 	globalRowIdx := 0
 	chk := e.children[0].newFirstChunk()
+	mutChunk := chunk.MutRowFromTypes(fields)


s/mutChunk/mutRow/

zz-jason · 2018-10-22T12:52:24Z

executor/update.go

@@ -42,6 +42,7 @@ type UpdateExec struct {
 	// columns2Handle stores relationship between column ordinal to its table handle.
 	// the columns ordinals is present in ordinal range format, @see executor.cols2Handle
 	columns2Handle cols2HandleSlice
+	evalBuffer     *chunk.MutRow


evalBuffer can be declared as chunk.MutRow

zz-jason · 2018-10-22T12:57:38Z

expression/builtin.go

@@ -49,11 +49,12 @@ func newBaseBuiltinFunc(ctx sessionctx.Context, args []Expression) baseBuiltinFu
 	if ctx == nil {
 		panic("ctx should not be nil")
 	}
-	return baseBuiltinFunc{
+	fn := baseBuiltinFunc{


the change of this file is irrelevant, can we revert it back?

zz-jason · 2018-10-22T12:57:58Z

expression/expression.go

@@ -36,6 +36,14 @@ const (
 	scalarFunctionFlag byte = 3
 )

+// Flag represents expression's property.
+type Flag byte


can be removed?

It seems to be used in next few lines. FlagHoldChunkMemory Flag = 1 << iota

Yeah, I mean this line and the flowing few lines can all be removed.

zz-jason · 2018-10-22T13:01:22Z

executor/insert_common.go

@@ -117,9 +119,30 @@ func (e *InsertValues) getColumns(tableCols []*table.Column) ([]*table.Column, e
 		return nil, errors.Trace(err)
 	}

+	e.initEvalBuffer()


This function call can be put to InsertExec.Open()?

maybe not convience to do that, because we need e.hasExtraHandle which is assigned in getColumns now.

getColumns() is called in the Next() function, Maybe we can move it to the Open() function:

InsertExec.Open: getColumns() initEvalBuffer() InsertExec.Next: e.insertRowsFromSelect(), or: e.insertRows()

another thing is, according to the callers of the function getColumns(), maybe we can also improve the performance of the replace statement:

3 executor/insert.go|132 col 17| cols, err := e.getColumns(e.Table.Cols()) 4 executor/replace.go|181 col 17| cols, err := e.getColumns(e.Table.Cols()) 5 executor/builder.go|576 col 28| columns, err := insertVal.getColumns(tableCols)

finally, I move getColumns to buildExecutor just like loadData does...and move initEvalBuffer to Open, and replace pointer to direct ref.

PTAL @zz-jason , although CI doesn't work

lysu · 2018-10-23T05:25:19Z

/run-all-tests

tiancaiamao · 2018-10-23T07:57:37Z

LGTM @zz-jason

zz-jason · 2018-10-23T08:02:22Z

executor/insert_common.go

@@ -50,9 +50,13 @@ type InsertValues struct {
 	GenColumns []*ast.ColumnName
 	GenExprs   []expression.Expression

+	InsertColumns []*table.Column


no need to export it? s/InsertColumns/insertColumns/

zz-jason · 2018-10-23T08:03:27Z

executor/insert_common.go

@@ -114,10 +120,25 @@ func (e *InsertValues) getColumns(tableCols []*table.Column) ([]*table.Column, e
 	// Check column whether is specified only once.
 	err = table.CheckOnce(cols)
 	if err != nil {
-		return nil, errors.Trace(err)
+		return errors.Trace(err)


no need to Trace any more?

lysu · 2018-10-23T08:14:47Z

/run-all-tests PTAL @zz-jason

zz-jason

LGTM

zz-jason · 2018-10-23T08:15:03Z

/run-all-tests

iamxy · 2018-10-23T09:29:55Z

/run-all-tests

bugfix fixed pingcap#7518 expression: MySQL compatible current_user function (pingcap#7801) plan: propagate constant over outer join (pingcap#7794) - extract `outerCol = const` from join conditions and filter conditions, substitute `outerCol` in join conditions with `const`; - extract `outerCol = innerCol` from join conditions, derive new join conditions based on this column equal condition and `outerCol` related expressions in join conditions and filter conditions; util/timeutil: fix data race caused by forgetting set stats lease to 0 (pingcap#7901) stats: handle ddl event for partition table (pingcap#7903) plan: implement Operand and Pattern of cascades planner. (pingcap#7910) planner: not convert to TableDual if empty range is derived from deferred constants (pingcap#7808) plan: move projEliminate behind aggEliminate (pingcap#7909) admin: fix admin check table bug of byte compare (pingcap#7887) * admin: remove reflect deepEqual stats: fix panic caused by empty histogram (pingcap#7912) plan: fix panic caused by empty schema of LogicalTableDual (pingcap#7906) * fix drop view if exist error (pingcap#7833) executor: refine `explain analyze` (pingcap#7888) executor: add an variable to compatible with MySQL insert for OGG (pingcap#7863) expression: maintain `DeferredExpr` in aggressive constant folding. (pingcap#7915) stats: fix histogram boundaries overflow error (pingcap#7883) ddl:support the definition of `null` change to `not null` using `alter table` (pingcap#7771) * ddl:support the definition of null change to not null using alter table ddl: add check when create table with foreign key. (pingcap#7885) * ddl: add check when create table with foreign key planner: eliminate if null on non null column (pingcap#7924) executor: fix a bug in point get (pingcap#7934) planner, executor: refine ColumnPrune for LogicalUnionAll (pingcap#7930) executor: fix panic when limit is too large (pingcap#7936) ddl: add TiDB version to metrics (pingcap#7902) stats: limit the length of sample values (pingcap#7931) vendor: update tipb (pingcap#7893) planner: support the Group and GroupExpr for the cascades planner (pingcap#7917) store/tikv: log more information when other err occurs (pingcap#7948) types: fix date time parse (pingcap#7933) ddl: just print error message when ddl job is normal to calcel, to eliminate noisy log (pingcap#7875) stats: update delta info for partition table (pingcap#7947) explaintest: add explain test for partition pruning (pingcap#7505) util: move disjoint set to util package (pingcap#7950) util: add PreAlloc4Row and Insert for Chunk and List (pingcap#7916) executor: add the slow log for commit (pingcap#7951) expression: add builtin json_keys (pingcap#7776) privilege: add USAGE in `show grants` for mysql compatibility (pingcap#7955) ddl: fix invailid ddl job panic (pingcap#7940) *: move ast.NewValueExpr to standalone parser_driver package (pingcap#7952) Make the ast package get rid of the dependency of types.Datum server: allow cors http request (pingcap#7939) *: move `Statement` and `RecordSet` from ast to sqlexec package (pingcap#7970) pr suggestion update executor/aggfuncs: split unit tests to corresponding file (pingcap#7993) store/tikv: fix typo (pingcap#7990) executor, planner: clone proj schema for different children in buildProj4Union (pingcap#7999) executor: let information_schema be the first database in ShowDatabases (pingcap#7938) stats: use local feedback for partition table (pingcap#7963) executor: add unit test for aggfuncs (pingcap#7966) server: add log for binary execute statement (pingcap#7987) admin: refine admin check decoder (pingcap#7862) executor: improve wide table insert & update performance (pingcap#7935) ddl: fix reassigned partition id in `truncate table` does not take effect (pingcap#7919) fix reassigned partition id in truncate table does not take effect add changelog for 2.1.0 rc4 (pingcap#8020) *: make parser package dependency as small as possible (pingcap#7989) parser: support `:=` in the `set` syntax (pingcap#8018) According to MySQL document, `set` use the = assignment operator, but the := assignment operator is also permitted stats: garbage collect stats for partition table (pingcap#7962) docs: add the proposal for the column pool (pingcap#7988) expression: refine built-in func truncate to support uint arg (pingcap#8000) stats: support show stats for partition table (pingcap#8023) stats: update error rate for partition table (pingcap#8022) stats: fix estimation for out of range point queries (pingcap#8015) *: move parser to a separate repository (pingcap#8036) executor: fix wrong result when index join on union scan. (pingcap#8031) Do not modify Plan of dataReaderBuilder directly, because it would impact next batch of outer rows, as well as other concurrent inner workers. Instead, build a local child builder to store the child plan. planner: fix a panic of a cached prepared statement with IndexScan (pingcap#8017) *: fix the issue of executing DDL after executing SQL failure in txn (pingcap#8044) * ddl, executor: fix the issue of executing DDL after executing SQL failure in txn add unit test remove debug info add like evaluator case sensitive test ddl, domain: make schema correct after canceling jobs (pingcap#7997) unit test fix code format proposal: maintaining histograms in plan. (pingcap#7605) support _tidb_rowid for table scan range (pingcap#8047) var rename fix

lysu added type/performance sig/execution SIG execution labels Oct 17, 2018

jackysp reviewed Oct 17, 2018

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lysu added the status/DNM label Oct 17, 2018

lysu added the require-LGT3 Indicates that the PR requires three LGTM. label Oct 18, 2018

lysu changed the title ~~executor: improve wide table insert performance~~ executor: improve wide table insert/update performance Oct 18, 2018

lysu changed the title ~~executor: improve wide table insert/update performance~~ executor: improve wide table insert & update performance Oct 18, 2018

lysu requested review from tiancaiamao and zz-jason October 18, 2018 12:46

lysu removed the status/DNM label Oct 19, 2018

lysu mentioned this pull request Oct 19, 2018

parser,executor: make load data support user_var in column list and set clause #7707

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tiancaiamao reviewed Oct 19, 2018

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zz-jason added type/enhancement The issue or PR belongs to an enhancement. and removed require-LGT3 Indicates that the PR requires three LGTM. type/performance labels Oct 23, 2018

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zz-jason added the status/LGT1 Indicates that a PR has LGTM 1. label Oct 23, 2018

lysu added 5 commits October 23, 2018 16:13

executor: improve wide table insert performance

dbd6d82

executor,expression: improve wide table update too

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address comment

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address comment

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executor: always copy version

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lysu added 4 commits October 23, 2018 16:13

address comment

51a6c26

refactor getColumns

936a110

no longer need pointer

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address comment

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zz-jason approved these changes Oct 23, 2018

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zz-jason added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Oct 23, 2018

zz-jason added 2 commits October 23, 2018 16:54

Merge branch 'master' into fix-wide-table-insert-perf

fd870f1

Merge branch 'master' into fix-wide-table-insert-perf

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Merge branch 'master' into fix-wide-table-insert-perf

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ngaut merged commit d8b52b8 into pingcap:master Oct 23, 2018

lysu mentioned this pull request Oct 23, 2018

executor: improve wide table insert & update performance (#7935) #8024

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zz-jason pushed a commit that referenced this pull request Oct 24, 2018

executor: improve wide table insert & update performance (#7935) (#8024)

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executor: improve wide table insert & update performance #7935

executor: improve wide table insert & update performance #7935

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lysu commented Oct 17, 2018 • edited Loading

What problem does this PR solve?

What is changed and how it works?

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