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// Copyright 2017 PingCAP, Inc.
//
// 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package statistics_test
import (
"context"
"fmt"
"math"
"os"
"runtime/pprof"
"strings"
"testing"
"time"
. "github.com/pingcap/check"
"github.com/pingcap/errors"
"github.com/pingcap/log"
"github.com/pingcap/parser/model"
"github.com/pingcap/parser/mysql"
"github.com/pingcap/tidb/domain"
"github.com/pingcap/tidb/kv"
plannercore "github.com/pingcap/tidb/planner/core"
"github.com/pingcap/tidb/session"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/sessionctx/stmtctx"
"github.com/pingcap/tidb/statistics"
"github.com/pingcap/tidb/statistics/handle"
"github.com/pingcap/tidb/store/mockstore"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/codec"
"github.com/pingcap/tidb/util/collate"
"github.com/pingcap/tidb/util/ranger"
"github.com/pingcap/tidb/util/testkit"
"github.com/pingcap/tidb/util/testleak"
"github.com/pingcap/tidb/util/testutil"
"go.uber.org/zap"
"go.uber.org/zap/zapcore"
)
const eps = 1e-9
var _ = SerialSuites(&testStatsSuite{})
type testStatsSuite struct {
store kv.Storage
do *domain.Domain
hook *logHook
testData testutil.TestData
}
func (s *testStatsSuite) SetUpSuite(c *C) {
testleak.BeforeTest()
// Add the hook here to avoid data race.
s.registerHook()
var err error
s.store, s.do, err = newStoreWithBootstrap()
c.Assert(err, IsNil)
s.testData, err = testutil.LoadTestSuiteData("testdata", "stats_suite")
c.Assert(err, IsNil)
}
func (s *testStatsSuite) TearDownSuite(c *C) {
s.do.Close()
c.Assert(s.store.Close(), IsNil)
testleak.AfterTest(c)()
c.Assert(s.testData.GenerateOutputIfNeeded(), IsNil)
}
func (s *testStatsSuite) registerHook() {
conf := &log.Config{Level: os.Getenv("log_level"), File: log.FileLogConfig{}}
_, r, _ := log.InitLogger(conf)
s.hook = &logHook{r.Core, ""}
lg := zap.New(s.hook)
log.ReplaceGlobals(lg, r)
}
type logHook struct {
zapcore.Core
results string
}
func (h *logHook) Write(entry zapcore.Entry, fields []zapcore.Field) error {
message := entry.Message
if idx := strings.Index(message, "[stats"); idx != -1 {
h.results = h.results + message
for _, f := range fields {
h.results = h.results + ", " + f.Key + "=" + h.field2String(f)
}
}
return nil
}
func (h *logHook) field2String(field zapcore.Field) string {
switch field.Type {
case zapcore.StringType:
return field.String
case zapcore.Int64Type, zapcore.Int32Type, zapcore.Uint32Type:
return fmt.Sprintf("%v", field.Integer)
case zapcore.Float64Type:
return fmt.Sprintf("%v", math.Float64frombits(uint64(field.Integer)))
case zapcore.StringerType:
return field.Interface.(fmt.Stringer).String()
}
return "not support"
}
func (h *logHook) Check(e zapcore.Entry, ce *zapcore.CheckedEntry) *zapcore.CheckedEntry {
if h.Enabled(e.Level) {
return ce.AddCore(e, h)
}
return ce
}
func newStoreWithBootstrap() (kv.Storage, *domain.Domain, error) {
store, err := mockstore.NewMockTikvStore()
if err != nil {
return nil, nil, errors.Trace(err)
}
session.SetSchemaLease(0)
session.DisableStats4Test()
domain.RunAutoAnalyze = false
do, err := session.BootstrapSession(store)
do.SetStatsUpdating(true)
return store, do, errors.Trace(err)
}
func cleanEnv(c *C, store kv.Storage, do *domain.Domain) {
tk := testkit.NewTestKit(c, store)
tk.MustExec("use test")
r := tk.MustQuery("show tables")
for _, tb := range r.Rows() {
tableName := tb[0]
tk.MustExec(fmt.Sprintf("drop table %v", tableName))
}
tk.MustExec("delete from mysql.stats_meta")
tk.MustExec("delete from mysql.stats_histograms")
tk.MustExec("delete from mysql.stats_buckets")
do.StatsHandle().Clear()
}
// generateIntDatum will generate a datum slice, every dimension is begin from 0, end with num - 1.
// If dimension is x, num is y, the total number of datum is y^x. And This slice is sorted.
func (s *testStatsSuite) generateIntDatum(dimension, num int) ([]types.Datum, error) {
length := int(math.Pow(float64(num), float64(dimension)))
ret := make([]types.Datum, length)
if dimension == 1 {
for i := 0; i < num; i++ {
ret[i] = types.NewIntDatum(int64(i))
}
} else {
sc := &stmtctx.StatementContext{TimeZone: time.Local}
// In this way, we can guarantee the datum is in order.
for i := 0; i < length; i++ {
data := make([]types.Datum, dimension)
j := i
for k := 0; k < dimension; k++ {
data[dimension-k-1].SetInt64(int64(j % num))
j = j / num
}
bytes, err := codec.EncodeKey(sc, nil, data...)
if err != nil {
return nil, err
}
ret[i].SetBytes(bytes)
}
}
return ret, nil
}
// mockStatsHistogram will create a statistics.Histogram, of which the data is uniform distribution.
func mockStatsHistogram(id int64, values []types.Datum, repeat int64, tp *types.FieldType) *statistics.Histogram {
ndv := len(values)
histogram := statistics.NewHistogram(id, int64(ndv), 0, 0, tp, ndv, 0)
for i := 0; i < ndv; i++ {
histogram.AppendBucket(&values[i], &values[i], repeat*int64(i+1), repeat)
}
return histogram
}
func mockStatsTable(tbl *model.TableInfo, rowCount int64) *statistics.Table {
histColl := statistics.HistColl{
PhysicalID: tbl.ID,
HavePhysicalID: true,
Count: rowCount,
Columns: make(map[int64]*statistics.Column, len(tbl.Columns)),
Indices: make(map[int64]*statistics.Index, len(tbl.Indices)),
}
statsTbl := &statistics.Table{
HistColl: histColl,
}
return statsTbl
}
func (s *testStatsSuite) prepareSelectivity(testKit *testkit.TestKit, c *C) *statistics.Table {
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a int primary key, b int, c int, d int, e int, index idx_cd(c, d), index idx_de(d, e))")
is := s.do.InfoSchema()
tb, err := is.TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
c.Assert(err, IsNil)
tbl := tb.Meta()
// mock the statistic table
statsTbl := mockStatsTable(tbl, 540)
// Set the value of columns' histogram.
colValues, err := s.generateIntDatum(1, 54)
c.Assert(err, IsNil)
for i := 1; i <= 5; i++ {
statsTbl.Columns[int64(i)] = &statistics.Column{Histogram: *mockStatsHistogram(int64(i), colValues, 10, types.NewFieldType(mysql.TypeLonglong)), Info: tbl.Columns[i-1]}
}
// Set the value of two indices' histograms.
idxValues, err := s.generateIntDatum(2, 3)
c.Assert(err, IsNil)
tp := types.NewFieldType(mysql.TypeBlob)
statsTbl.Indices[1] = &statistics.Index{Histogram: *mockStatsHistogram(1, idxValues, 60, tp), Info: tbl.Indices[0]}
statsTbl.Indices[2] = &statistics.Index{Histogram: *mockStatsHistogram(2, idxValues, 60, tp), Info: tbl.Indices[1]}
return statsTbl
}
func (s *testStatsSuite) TestSelectivity(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
statsTbl := s.prepareSelectivity(testKit, c)
is := s.do.InfoSchema()
longExpr := "0 < a and a = 1 "
for i := 1; i < 64; i++ {
longExpr += fmt.Sprintf(" and a > %d ", i)
}
tests := []struct {
exprs string
selectivity float64
}{
{
exprs: "a > 0 and a < 2",
selectivity: 0.01851851851,
},
{
exprs: "a >= 1 and a < 2",
selectivity: 0.01851851851,
},
{
exprs: "a >= 1 and b > 1 and a < 2",
selectivity: 0.01783264746,
},
{
exprs: "a >= 1 and c > 1 and a < 2",
selectivity: 0.00617283950,
},
{
exprs: "a >= 1 and c >= 1 and a < 2",
selectivity: 0.01234567901,
},
{
exprs: "d = 0 and e = 1",
selectivity: 0.11111111111,
},
{
exprs: "b > 1",
selectivity: 0.96296296296,
},
{
exprs: "a > 1 and b < 2 and c > 3 and d < 4 and e > 5",
selectivity: 0,
},
{
exprs: longExpr,
selectivity: 0.001,
},
}
ctx := context.Background()
for _, tt := range tests {
sql := "select * from t where " + tt.exprs
comment := Commentf("for %s", tt.exprs)
sctx := testKit.Se.(sessionctx.Context)
stmts, err := session.Parse(sctx, sql)
c.Assert(err, IsNil, Commentf("error %v, for expr %s", err, tt.exprs))
c.Assert(stmts, HasLen, 1)
err = plannercore.Preprocess(sctx, stmts[0], is)
c.Assert(err, IsNil, comment)
p, _, err := plannercore.BuildLogicalPlan(ctx, sctx, stmts[0], is)
c.Assert(err, IsNil, Commentf("error %v, for building plan, expr %s", err, tt.exprs))
sel := p.(plannercore.LogicalPlan).Children()[0].(*plannercore.LogicalSelection)
ds := sel.Children()[0].(*plannercore.DataSource)
histColl := statsTbl.GenerateHistCollFromColumnInfo(ds.Columns, ds.Schema().Columns)
ratio, _, err := histColl.Selectivity(sctx, sel.Conditions, nil)
c.Assert(err, IsNil, comment)
c.Assert(math.Abs(ratio-tt.selectivity) < eps, IsTrue, Commentf("for %s, needed: %v, got: %v", tt.exprs, tt.selectivity, ratio))
histColl.Count *= 10
ratio, _, err = histColl.Selectivity(sctx, sel.Conditions, nil)
c.Assert(err, IsNil, comment)
c.Assert(math.Abs(ratio-tt.selectivity) < eps, IsTrue, Commentf("for %s, needed: %v, got: %v", tt.exprs, tt.selectivity, ratio))
}
}
// TestDiscreteDistribution tests the estimation for discrete data distribution. This is more common when the index
// consists several columns, and the first column has small NDV.
func (s *testStatsSuite) TestDiscreteDistribution(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a char(10), b int, key idx(a, b))")
for i := 0; i < 499; i++ {
testKit.MustExec(fmt.Sprintf("insert into t values ('cn', %d)", i))
}
for i := 0; i < 10; i++ {
testKit.MustExec("insert into t values ('tw', 0)")
}
testKit.MustExec("analyze table t")
var (
input []string
output [][]string
)
s.testData.GetTestCases(c, &input, &output)
for i, tt := range input {
s.testData.OnRecord(func() {
output[i] = s.testData.ConvertRowsToStrings(testKit.MustQuery(tt).Rows())
})
testKit.MustQuery(tt).Check(testkit.Rows(output[i]...))
}
}
func (s *testStatsSuite) TestSelectCombinedLowBound(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(id int auto_increment, kid int, pid int, primary key(id), key(kid, pid))")
testKit.MustExec("insert into t (kid, pid) values (1,2), (1,3), (1,4),(1, 11), (1, 12), (1, 13), (1, 14), (2, 2), (2, 3), (2, 4)")
testKit.MustExec("analyze table t")
var (
input []string
output [][]string
)
s.testData.GetTestCases(c, &input, &output)
for i, tt := range input {
s.testData.OnRecord(func() {
output[i] = s.testData.ConvertRowsToStrings(testKit.MustQuery(tt).Rows())
})
testKit.MustQuery(tt).Check(testkit.Rows(output[i]...))
}
}
func getRange(start, end int64) []*ranger.Range {
ran := &ranger.Range{
LowVal: []types.Datum{types.NewIntDatum(start)},
HighVal: []types.Datum{types.NewIntDatum(end)},
}
return []*ranger.Range{ran}
}
func (s *testStatsSuite) TestOutOfRangeEQEstimation(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a int)")
for i := 0; i < 1000; i++ {
testKit.MustExec(fmt.Sprintf("insert into t values (%v)", i/4)) // 0 ~ 249
}
testKit.MustExec("analyze table t")
h := s.do.StatsHandle()
table, err := s.do.InfoSchema().TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
c.Assert(err, IsNil)
statsTbl := h.GetTableStats(table.Meta())
sc := &stmtctx.StatementContext{}
col := statsTbl.Columns[table.Meta().Columns[0].ID]
count, err := col.GetColumnRowCount(sc, getRange(250, 250), 0, false)
c.Assert(err, IsNil)
c.Assert(count, Equals, float64(0))
for i := 0; i < 8; i++ {
count, err := col.GetColumnRowCount(sc, getRange(250, 250), int64(i+1), false)
c.Assert(err, IsNil)
c.Assert(count, Equals, math.Min(float64(i+1), 4)) // estRows must be less than modifyCnt
}
}
func (s *testStatsSuite) TestEstimationForUnknownValues(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a int, b int, key idx(a, b))")
testKit.MustExec("analyze table t")
for i := 0; i < 10; i++ {
testKit.MustExec(fmt.Sprintf("insert into t values (%d, %d)", i, i))
}
h := s.do.StatsHandle()
c.Assert(h.DumpStatsDeltaToKV(handle.DumpAll), IsNil)
testKit.MustExec("analyze table t")
for i := 0; i < 10; i++ {
testKit.MustExec(fmt.Sprintf("insert into t values (%d, %d)", i+10, i+10))
}
c.Assert(h.DumpStatsDeltaToKV(handle.DumpAll), IsNil)
c.Assert(h.Update(s.do.InfoSchema()), IsNil)
table, err := s.do.InfoSchema().TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
c.Assert(err, IsNil)
statsTbl := h.GetTableStats(table.Meta())
sc := &stmtctx.StatementContext{}
colID := table.Meta().Columns[0].ID
count, err := statsTbl.GetRowCountByColumnRanges(sc, colID, getRange(30, 30))
c.Assert(err, IsNil)
c.Assert(count, Equals, 0.2)
count, err = statsTbl.GetRowCountByColumnRanges(sc, colID, getRange(9, 30))
c.Assert(err, IsNil)
c.Assert(count, Equals, 2.4000000000000004)
count, err = statsTbl.GetRowCountByColumnRanges(sc, colID, getRange(9, math.MaxInt64))
c.Assert(err, IsNil)
c.Assert(count, Equals, 2.4000000000000004)
idxID := table.Meta().Indices[0].ID
count, err = statsTbl.GetRowCountByIndexRanges(sc, idxID, getRange(30, 30))
c.Assert(err, IsNil)
c.Assert(count, Equals, 0.2)
count, err = statsTbl.GetRowCountByIndexRanges(sc, idxID, getRange(9, 30))
c.Assert(err, IsNil)
c.Assert(count, Equals, 2.2)
testKit.MustExec("truncate table t")
testKit.MustExec("insert into t values (null, null)")
testKit.MustExec("analyze table t")
table, err = s.do.InfoSchema().TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
c.Assert(err, IsNil)
statsTbl = h.GetTableStats(table.Meta())
colID = table.Meta().Columns[0].ID
count, err = statsTbl.GetRowCountByColumnRanges(sc, colID, getRange(1, 30))
c.Assert(err, IsNil)
c.Assert(count, Equals, 0.0)
testKit.MustExec("drop table t")
testKit.MustExec("create table t(a int, b int, index idx(b))")
testKit.MustExec("insert into t values (1,1)")
testKit.MustExec("analyze table t")
table, err = s.do.InfoSchema().TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
c.Assert(err, IsNil)
statsTbl = h.GetTableStats(table.Meta())
colID = table.Meta().Columns[0].ID
count, err = statsTbl.GetRowCountByColumnRanges(sc, colID, getRange(2, 2))
c.Assert(err, IsNil)
c.Assert(count, Equals, 0.0)
idxID = table.Meta().Indices[0].ID
count, err = statsTbl.GetRowCountByIndexRanges(sc, idxID, getRange(2, 2))
c.Assert(err, IsNil)
c.Assert(count, Equals, 0.0)
}
func (s *testStatsSuite) TestEstimationUniqueKeyEqualConds(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a int, b int, c int, unique key(b))")
testKit.MustExec("insert into t values (1,1,1),(2,2,2),(3,3,3),(4,4,4),(5,5,5),(6,6,6),(7,7,7)")
testKit.MustExec("analyze table t with 4 cmsketch width, 1 cmsketch depth;")
table, err := s.do.InfoSchema().TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
c.Assert(err, IsNil)
statsTbl := s.do.StatsHandle().GetTableStats(table.Meta())
sc := &stmtctx.StatementContext{}
idxID := table.Meta().Indices[0].ID
count, err := statsTbl.GetRowCountByIndexRanges(sc, idxID, getRange(7, 7))
c.Assert(err, IsNil)
c.Assert(count, Equals, 1.0)
count, err = statsTbl.GetRowCountByIndexRanges(sc, idxID, getRange(6, 6))
c.Assert(err, IsNil)
c.Assert(count, Equals, 1.0)
colID := table.Meta().Columns[0].ID
count, err = statsTbl.GetRowCountByIntColumnRanges(sc, colID, getRange(7, 7))
c.Assert(err, IsNil)
c.Assert(count, Equals, 1.0)
count, err = statsTbl.GetRowCountByIntColumnRanges(sc, colID, getRange(6, 6))
c.Assert(err, IsNil)
c.Assert(count, Equals, 1.0)
}
func (s *testStatsSuite) TestPrimaryKeySelectivity(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a char(10) primary key, b int)")
var input, output [][]string
s.testData.GetTestCases(c, &input, &output)
for i, ts := range input {
for j, tt := range ts {
if j != len(ts)-1 {
testKit.MustExec(tt)
}
s.testData.OnRecord(func() {
if j == len(ts)-1 {
output[i] = s.testData.ConvertRowsToStrings(testKit.MustQuery(tt).Rows())
}
})
if j == len(ts)-1 {
testKit.MustQuery(tt).Check(testkit.Rows(output[i]...))
}
}
}
}
func BenchmarkSelectivity(b *testing.B) {
c := &C{}
s := &testStatsSuite{}
s.SetUpSuite(c)
defer s.TearDownSuite(c)
testKit := testkit.NewTestKit(c, s.store)
statsTbl := s.prepareSelectivity(testKit, c)
is := s.do.InfoSchema()
exprs := "a > 1 and b < 2 and c > 3 and d < 4 and e > 5"
sql := "select * from t where " + exprs
comment := Commentf("for %s", exprs)
sctx := testKit.Se.(sessionctx.Context)
stmts, err := session.Parse(sctx, sql)
c.Assert(err, IsNil, Commentf("error %v, for expr %s", err, exprs))
c.Assert(stmts, HasLen, 1)
err = plannercore.Preprocess(sctx, stmts[0], is)
c.Assert(err, IsNil, comment)
p, _, err := plannercore.BuildLogicalPlan(context.Background(), sctx, stmts[0], is)
c.Assert(err, IsNil, Commentf("error %v, for building plan, expr %s", err, exprs))
file, err := os.Create("cpu.profile")
c.Assert(err, IsNil)
defer file.Close()
pprof.StartCPUProfile(file)
b.Run("Selectivity", func(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
_, _, err := statsTbl.Selectivity(sctx, p.(plannercore.LogicalPlan).Children()[0].(*plannercore.LogicalSelection).Conditions, nil)
c.Assert(err, IsNil)
}
b.ReportAllocs()
})
pprof.StopCPUProfile()
}
func (s *testStatsSuite) TestColumnIndexNullEstimation(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a int, b int, c int, index idx_b(b), index idx_c_a(c, a))")
testKit.MustExec("insert into t values(1,null,1),(2,null,2),(3,3,3),(4,null,4),(null,null,null);")
h := s.do.StatsHandle()
c.Assert(h.DumpStatsDeltaToKV(handle.DumpAll), IsNil)
testKit.MustExec("analyze table t")
var (
input []string
output [][]string
)
s.testData.GetTestCases(c, &input, &output)
for i := 0; i < 5; i++ {
s.testData.OnRecord(func() {
output[i] = s.testData.ConvertRowsToStrings(testKit.MustQuery(input[i]).Rows())
})
testKit.MustQuery(input[i]).Check(testkit.Rows(output[i]...))
}
// Make sure column stats has been loaded.
testKit.MustExec(`explain select * from t where a is null`)
c.Assert(h.LoadNeededHistograms(), IsNil)
for i := 5; i < len(input); i++ {
s.testData.OnRecord(func() {
output[i] = s.testData.ConvertRowsToStrings(testKit.MustQuery(input[i]).Rows())
})
testKit.MustQuery(input[i]).Check(testkit.Rows(output[i]...))
}
}
func (s *testStatsSuite) TestUniqCompEqualEst(c *C) {
defer cleanEnv(c, s.store, s.do)
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a int, b int, primary key(a, b))")
testKit.MustExec("insert into t values(1,1),(1,2),(1,3),(1,4),(1,5),(1,6),(1,7),(1,8),(1,9),(1,10)")
h := s.do.StatsHandle()
c.Assert(h.DumpStatsDeltaToKV(handle.DumpAll), IsNil)
testKit.MustExec("analyze table t")
var (
input []string
output [][]string
)
s.testData.GetTestCases(c, &input, &output)
for i := 0; i < 1; i++ {
s.testData.OnRecord(func() {
output[i] = s.testData.ConvertRowsToStrings(testKit.MustQuery(input[i]).Rows())
})
testKit.MustQuery(input[i]).Check(testkit.Rows(output[i]...))
}
}
func (s *testStatsSuite) TestSelectivityGreedyAlgo(c *C) {
nodes := make([]*statistics.StatsNode, 3)
nodes[0] = statistics.MockStatsNode(1, 3, 2)
nodes[1] = statistics.MockStatsNode(2, 5, 2)
nodes[2] = statistics.MockStatsNode(3, 9, 2)
// Sets should not overlap on mask, so only nodes[0] is chosen.
usedSets := statistics.GetUsableSetsByGreedy(nodes)
c.Assert(len(usedSets), Equals, 1)
c.Assert(usedSets[0].ID, Equals, int64(1))
nodes[0], nodes[1] = nodes[1], nodes[0]
// Sets chosen should be stable, so the returned node is still the one with ID 1.
usedSets = statistics.GetUsableSetsByGreedy(nodes)
c.Assert(len(usedSets), Equals, 1)
c.Assert(usedSets[0].ID, Equals, int64(1))
}
func (s *testStatsSuite) TestCollationColumnEstimate(c *C) {
defer cleanEnv(c, s.store, s.do)
tk := testkit.NewTestKit(c, s.store)
collate.SetNewCollationEnabledForTest(true)
defer collate.SetNewCollationEnabledForTest(false)
tk.MustExec("use test")
tk.MustExec("drop table if exists t")
tk.MustExec("create table t(a varchar(20) collate utf8mb4_general_ci)")
tk.MustExec("insert into t values('aaa'), ('bbb'), ('AAA'), ('BBB')")
h := s.do.StatsHandle()
c.Assert(h.DumpStatsDeltaToKV(handle.DumpAll), IsNil)
tk.MustExec("analyze table t")
tk.MustExec("explain select * from t where a = 'aaa'")
c.Assert(h.LoadNeededHistograms(), IsNil)
var (
input []string
output [][]string
)
s.testData.GetTestCases(c, &input, &output)
for i := 0; i < len(input); i++ {
s.testData.OnRecord(func() {
output[i] = s.testData.ConvertRowsToStrings(tk.MustQuery(input[i]).Rows())
})
tk.MustQuery(input[i]).Check(testkit.Rows(output[i]...))
}
}