Files
tidb/pkg/statistics/histogram_test.go

738 lines
21 KiB
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// Copyright 2018 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,
// 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 statistics
import (
"fmt"
"testing"
"time"
"github.com/pingcap/failpoint"
"github.com/pingcap/tidb/pkg/meta/model"
"github.com/pingcap/tidb/pkg/parser/ast"
"github.com/pingcap/tidb/pkg/parser/mysql"
"github.com/pingcap/tidb/pkg/types"
"github.com/pingcap/tidb/pkg/util/codec"
"github.com/pingcap/tidb/pkg/util/mock"
"github.com/stretchr/testify/require"
)
func TestTruncateHistogram(t *testing.T) {
hist := NewHistogram(0, 0, 0, 0, types.NewFieldType(mysql.TypeLonglong), 1, 0)
low, high := types.NewIntDatum(0), types.NewIntDatum(1)
hist.AppendBucket(&low, &high, 0, 1)
newHist := hist.TruncateHistogram(1)
require.True(t, HistogramEqual(hist, newHist, true))
newHist = hist.TruncateHistogram(0)
require.Equal(t, 0, newHist.Len())
}
func TestValueToString4InvalidKey(t *testing.T) {
bytes, err := codec.EncodeKey(time.UTC, nil, types.NewDatum(1), types.NewDatum(0.5))
require.NoError(t, err)
// Append invalid flag.
bytes = append(bytes, 20)
datum := types.NewDatum(bytes)
res, err := ValueToString(nil, &datum, 3, nil)
require.NoError(t, err)
require.Equal(t, "(1, 0.5, \x14)", res)
}
type bucket4Test struct {
lower int64
upper int64
count int64
repeat int64
ndv int64
}
type topN4Test struct {
data int64
count int64
}
func genHist4Test(t *testing.T, buckets []*bucket4Test, totColSize int64) *Histogram {
h := NewHistogram(0, 0, 0, 0, types.NewFieldType(mysql.TypeBlob), len(buckets), totColSize)
for _, bucket := range buckets {
lower, err := codec.EncodeKey(time.UTC, nil, types.NewIntDatum(bucket.lower))
require.NoError(t, err)
upper, err := codec.EncodeKey(time.UTC, nil, types.NewIntDatum(bucket.upper))
require.NoError(t, err)
di, du := types.NewBytesDatum(lower), types.NewBytesDatum(upper)
h.AppendBucketWithNDV(&di, &du, bucket.count, bucket.repeat, bucket.ndv)
}
return h
}
func TestMergePartitionLevelHist(t *testing.T) {
type testCase struct {
partitionHists [][]*bucket4Test
totColSize []int64
popedTopN []topN4Test
expHist []*bucket4Test
expBucketNumber int
}
tests := []testCase{
{
partitionHists: [][]*bucket4Test{
{
// Col(1) = [1, 4,|| 6, 9, 9,|| 12, 12, 12,|| 13, 14, 15]
{
lower: 1,
upper: 4,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 9,
count: 5,
repeat: 2,
ndv: 2,
},
{
lower: 12,
upper: 12,
count: 8,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 15,
count: 11,
repeat: 1,
ndv: 3,
},
},
// Col(2) = [2, 5,|| 6, 7, 7,|| 11, 11, 11,|| 13, 14, 17]
{
{
lower: 2,
upper: 5,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 7,
count: 5,
repeat: 2,
ndv: 2,
},
{
lower: 11,
upper: 11,
count: 8,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 17,
count: 11,
repeat: 1,
ndv: 3,
},
},
},
totColSize: []int64{11, 11},
popedTopN: []topN4Test{},
expHist: []*bucket4Test{
{
lower: 1,
upper: 9,
count: 10,
repeat: 2,
ndv: 7,
},
{
lower: 11,
upper: 17,
count: 22,
repeat: 1,
ndv: 8,
},
},
expBucketNumber: 2,
},
{
partitionHists: [][]*bucket4Test{
{
// Col(1) = [1, 4,|| 6, 9, 9,|| 12, 12, 12,|| 13, 14, 15]
{
lower: 1,
upper: 4,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 9,
count: 5,
repeat: 2,
ndv: 2,
},
{
lower: 12,
upper: 12,
count: 8,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 15,
count: 11,
repeat: 1,
ndv: 3,
},
},
// Col(2) = [2, 5,|| 6, 7, 7,|| 11, 11, 11,|| 13, 14, 17]
{
{
lower: 2,
upper: 5,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 7,
count: 5,
repeat: 2,
ndv: 2,
},
{
lower: 11,
upper: 11,
count: 8,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 17,
count: 11,
repeat: 1,
ndv: 3,
},
},
},
totColSize: []int64{11, 11},
popedTopN: []topN4Test{
{
data: 18,
count: 5,
},
{
data: 4,
count: 6,
},
},
expHist: []*bucket4Test{
{
lower: 1,
upper: 5,
count: 10,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 12,
count: 22,
repeat: 3,
ndv: 6,
},
{
lower: 13,
upper: 18,
count: 33,
repeat: 5,
ndv: 5,
},
},
expBucketNumber: 3,
},
{
// issue#49023
partitionHists: [][]*bucket4Test{
{
// Col(1) = [1, 4,|| 6, 9, 9,|| 12, 12, 12,|| 13, 14, 15]
{
lower: 1,
upper: 4,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 9,
count: 5,
repeat: 2,
ndv: 2,
},
{
lower: 12,
upper: 12,
count: 5,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 15,
count: 11,
repeat: 1,
ndv: 3,
},
},
// Col(2) = [2, 5,|| 6, 7, 7,|| 11, 11, 11,|| 13, 14, 17]
{
{
lower: 2,
upper: 5,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 7,
count: 2,
repeat: 2,
ndv: 2,
},
{
lower: 11,
upper: 11,
count: 8,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 17,
count: 11,
repeat: 1,
ndv: 3,
},
},
// Col(3) = [2, 5,|| 6, 7, 7,|| 11, 11, 11,|| 13, 14, 17]
{
{
lower: 2,
upper: 5,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 7,
count: 2,
repeat: 2,
ndv: 2,
},
{
lower: 11,
upper: 11,
count: 8,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 17,
count: 11,
repeat: 1,
ndv: 3,
},
},
// Col(4) = [2, 5,|| 6, 7, 7,|| 11, 11, 11,|| 13, 14, 17]
{
{
lower: 2,
upper: 5,
count: 2,
repeat: 1,
ndv: 2,
},
{
lower: 6,
upper: 7,
count: 2,
repeat: 2,
ndv: 2,
},
{
lower: 11,
upper: 11,
count: 8,
repeat: 3,
ndv: 1,
},
{
lower: 13,
upper: 17,
count: 11,
repeat: 1,
ndv: 3,
},
},
},
totColSize: []int64{11, 11, 11, 11},
popedTopN: []topN4Test{
{
data: 18,
count: 5,
},
{
data: 4,
count: 6,
},
},
expHist: []*bucket4Test{
{
lower: 1,
upper: 9,
count: 17,
repeat: 2,
ndv: 8,
},
{
lower: 11,
upper: 11,
count: 35,
repeat: 9,
ndv: 1,
},
{
lower: 13,
upper: 18,
count: 55,
repeat: 5,
ndv: 6,
},
},
expBucketNumber: 3,
},
}
failpoint.Enable("github.com/pingcap/pkg/statistics/enableTopNNDV", `return(true)`)
for ii, tt := range tests {
var expTotColSize int64
hists := make([]*Histogram, 0, len(tt.partitionHists))
for i := range tt.partitionHists {
hists = append(hists, genHist4Test(t, tt.partitionHists[i], tt.totColSize[i]))
expTotColSize += tt.totColSize[i]
}
ctx := mock.NewContext()
sc := ctx.GetSessionVars().StmtCtx
poped := make([]TopNMeta, 0, len(tt.popedTopN))
for _, top := range tt.popedTopN {
b, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(top.data))
require.NoError(t, err)
tmp := TopNMeta{
Encoded: b,
Count: uint64(top.count),
}
poped = append(poped, tmp)
}
globalHist, err := MergePartitionHist2GlobalHist(sc, hists, poped, int64(tt.expBucketNumber), true, Version2)
require.NoError(t, err)
require.Equal(t, tt.expBucketNumber, len(globalHist.Buckets))
for i, b := range tt.expHist {
lo, err := ValueToString(ctx.GetSessionVars(), globalHist.GetLower(i), 1, []byte{types.KindInt64})
require.NoError(t, err, "failed at #%d case, %d bucket", ii, i)
up, err := ValueToString(ctx.GetSessionVars(), globalHist.GetUpper(i), 1, []byte{types.KindInt64})
require.NoError(t, err, "failed at #%d case, %d bucket", ii, i)
require.Equal(t, fmt.Sprintf("%v", b.lower), lo, "failed at #%d case, %d bucket", ii, i)
require.Equal(t, fmt.Sprintf("%v", b.upper), up, "failed at #%d case, %d bucket", ii, i)
require.Equal(t, b.count, globalHist.Buckets[i].Count, "failed at #%d case, %d bucket", ii, i)
require.Equal(t, b.repeat, globalHist.Buckets[i].Repeat, "failed at #%d case, %d bucket", ii, i)
require.Equal(t, b.ndv, globalHist.Buckets[i].NDV, "failed at #%d case, %d bucket", ii, i)
}
require.Equal(t, expTotColSize, globalHist.TotColSize, "failed at #%d case", ii)
}
failpoint.Disable("github.com/pingcap/pkg/statistics/enableTopNNDV")
}
func genBucket4Merging4Test(lower, upper, ndv, disjointNDV int64) bucket4Merging {
l := types.NewIntDatum(lower)
r := types.NewIntDatum(upper)
return bucket4Merging{
lower: &l,
upper: &r,
Bucket: Bucket{
NDV: ndv,
Count: ndv,
},
disjointNDV: disjointNDV,
}
}
func TestMergeBucketNDV(t *testing.T) {
type testData struct {
left bucket4Merging
right bucket4Merging
result bucket4Merging
}
tests := []testData{
{
left: genBucket4Merging4Test(1, 2, 2, 0),
right: genBucket4Merging4Test(1, 2, 3, 0),
result: genBucket4Merging4Test(1, 2, 3, 0),
},
{
left: genBucket4Merging4Test(1, 3, 2, 0),
right: genBucket4Merging4Test(2, 3, 2, 0),
result: genBucket4Merging4Test(1, 3, 3, 0),
},
{
left: genBucket4Merging4Test(1, 3, 2, 0),
right: genBucket4Merging4Test(4, 6, 2, 2),
result: genBucket4Merging4Test(1, 3, 2, 4),
},
{
left: genBucket4Merging4Test(1, 5, 5, 0),
right: genBucket4Merging4Test(2, 6, 5, 0),
result: genBucket4Merging4Test(1, 6, 6, 0),
},
{
left: genBucket4Merging4Test(3, 5, 3, 0),
right: genBucket4Merging4Test(2, 6, 4, 0),
result: genBucket4Merging4Test(2, 6, 5, 0),
},
}
sc := mock.NewContext().GetSessionVars().StmtCtx
for i, tt := range tests {
res, err := mergeBucketNDV(sc, &tt.left, &tt.right)
require.NoError(t, err, "failed at #%Td case", i)
require.Equal(t, res.lower.GetInt64(), tt.result.lower.GetInt64(), "failed at #%Td case", i)
require.Equal(t, res.upper.GetInt64(), tt.result.upper.GetInt64(), "failed at #%Td case", i)
require.Equal(t, res.NDV, tt.result.NDV, "failed at #%Td case", i)
require.Equal(t, res.disjointNDV, tt.result.disjointNDV, "failed at #%Td case", i)
}
}
func TestIndexQueryBytes(t *testing.T) {
ctx := mock.NewContext()
sc := ctx.GetSessionVars().StmtCtx
idx := &Index{Info: &model.IndexInfo{Columns: []*model.IndexColumn{{Name: ast.NewCIStr("a"), Offset: 0}}}}
idx.Histogram = *NewHistogram(0, 15, 0, 0, types.NewFieldType(mysql.TypeBlob), 0, 0)
low, err1 := codec.EncodeKey(sc.TimeZone(), nil, types.NewBytesDatum([]byte("0")))
require.NoError(t, err1)
high, err2 := codec.EncodeKey(sc.TimeZone(), nil, types.NewBytesDatum([]byte("3")))
require.NoError(t, err2)
idx.Bounds.AppendBytes(0, low)
idx.Bounds.AppendBytes(0, high)
idx.Buckets = append(idx.Buckets, Bucket{Repeat: 10, Count: 20, NDV: 20})
idx.PreCalculateScalar()
idx.CMSketch = nil
// Count / NDV
require.Equal(t, idx.QueryBytes(nil, low), uint64(1))
// Repeat
require.Equal(t, idx.QueryBytes(nil, high), uint64(10))
}
type histogramInputAndOutput struct {
inputHist *Histogram
inputHistToStr string
outputHistToStr string
}
func TestStandardizeForV2AnalyzeIndex(t *testing.T) {
// 1. prepare expected input and output histograms (in string)
testData := []*histogramInputAndOutput{
{
inputHistToStr: "index:0 ndv:6\n" +
"num: 0 lower_bound: 111 upper_bound: 111 repeats: 0 ndv: 0\n" +
"num: 0 lower_bound: 123 upper_bound: 123 repeats: 0 ndv: 0\n" +
"num: 10 lower_bound: 34567 upper_bound: 5 repeats: 3 ndv: 2",
outputHistToStr: "index:0 ndv:6\n" +
"num: 10 lower_bound: 34567 upper_bound: 5 repeats: 3 ndv: 0",
},
{
inputHistToStr: "index:0 ndv:6\n" +
"num: 0 lower_bound: 111 upper_bound: 111 repeats: 0 ndv: 0\n" +
"num: 0 lower_bound: 123 upper_bound: 123 repeats: 0 ndv: 0\n" +
"num: 0 lower_bound: 34567 upper_bound: 5 repeats: 0 ndv: 0",
outputHistToStr: "index:0 ndv:6",
},
{
inputHistToStr: "index:0 ndv:6\n" +
"num: 10 lower_bound: 34567 upper_bound: 5 repeats: 3 ndv: 2\n" +
"num: 0 lower_bound: 876 upper_bound: 876 repeats: 0 ndv: 0\n" +
"num: 0 lower_bound: 990 upper_bound: 990 repeats: 0 ndv: 0",
outputHistToStr: "index:0 ndv:6\n" +
"num: 10 lower_bound: 34567 upper_bound: 5 repeats: 3 ndv: 0",
},
{
inputHistToStr: "index:0 ndv:6\n" +
"num: 10 lower_bound: 111 upper_bound: 111 repeats: 10 ndv: 1\n" +
"num: 12 lower_bound: 123 upper_bound: 34567 repeats: 4 ndv: 20\n" +
"num: 10 lower_bound: 5 upper_bound: 990 repeats: 6 ndv: 2",
outputHistToStr: "index:0 ndv:6\n" +
"num: 10 lower_bound: 111 upper_bound: 111 repeats: 10 ndv: 0\n" +
"num: 12 lower_bound: 123 upper_bound: 34567 repeats: 4 ndv: 0\n" +
"num: 10 lower_bound: 5 upper_bound: 990 repeats: 6 ndv: 0",
},
{
inputHistToStr: "index:0 ndv:6\n" +
"num: 0 lower_bound: 111 upper_bound: 111 repeats: 0 ndv: 0\n" +
"num: 0 lower_bound: 123 upper_bound: 123 repeats: 0 ndv: 0\n" +
"num: 10 lower_bound: 34567 upper_bound: 34567 repeats: 3 ndv: 2\n" +
"num: 0 lower_bound: 5 upper_bound: 5 repeats: 0 ndv: 0\n" +
"num: 0 lower_bound: 876 upper_bound: 876 repeats: 0 ndv: 0\n" +
"num: 10 lower_bound: 990 upper_bound: 990 repeats: 3 ndv: 2\n" +
"num: 10 lower_bound: 95 upper_bound: 95 repeats: 3 ndv: 2",
outputHistToStr: "index:0 ndv:6\n" +
"num: 10 lower_bound: 34567 upper_bound: 34567 repeats: 3 ndv: 0\n" +
"num: 10 lower_bound: 990 upper_bound: 990 repeats: 3 ndv: 0\n" +
"num: 10 lower_bound: 95 upper_bound: 95 repeats: 3 ndv: 0",
},
{
inputHistToStr: "index:0 ndv:6\n" +
"num: 0 lower_bound: 111 upper_bound: 111 repeats: 0 ndv: 0\n" +
"num: 0 lower_bound: 123 upper_bound: 123 repeats: 0 ndv: 0\n" +
"num: 10 lower_bound: 34567 upper_bound: 34567 repeats: 3 ndv: 2\n" +
"num: 0 lower_bound: 5 upper_bound: 5 repeats: 0 ndv: 0\n" +
"num: 10 lower_bound: 876 upper_bound: 876 repeats: 3 ndv: 2\n" +
"num: 10 lower_bound: 990 upper_bound: 990 repeats: 3 ndv: 2\n" +
"num: 0 lower_bound: 95 upper_bound: 95 repeats: 0 ndv: 0",
outputHistToStr: "index:0 ndv:6\n" +
"num: 10 lower_bound: 34567 upper_bound: 34567 repeats: 3 ndv: 0\n" +
"num: 10 lower_bound: 876 upper_bound: 876 repeats: 3 ndv: 0\n" +
"num: 10 lower_bound: 990 upper_bound: 990 repeats: 3 ndv: 0",
},
}
// 2. prepare the actual Histogram input
ctx := mock.NewContext()
sc := ctx.GetSessionVars().StmtCtx
val0, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(111))
require.NoError(t, err)
val1, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(123))
require.NoError(t, err)
val2, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(34567))
require.NoError(t, err)
val3, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(5))
require.NoError(t, err)
val4, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(876))
require.NoError(t, err)
val5, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(990))
require.NoError(t, err)
val6, err := codec.EncodeKey(sc.TimeZone(), nil, types.NewIntDatum(95))
require.NoError(t, err)
val0Bytes := types.NewBytesDatum(val0)
val1Bytes := types.NewBytesDatum(val1)
val2Bytes := types.NewBytesDatum(val2)
val3Bytes := types.NewBytesDatum(val3)
val4Bytes := types.NewBytesDatum(val4)
val5Bytes := types.NewBytesDatum(val5)
val6Bytes := types.NewBytesDatum(val6)
hist0 := NewHistogram(0, 6, 0, 0, types.NewFieldType(mysql.TypeBlob), 0, 0)
hist0.AppendBucketWithNDV(&val0Bytes, &val0Bytes, 0, 0, 0)
hist0.AppendBucketWithNDV(&val1Bytes, &val1Bytes, 0, 0, 0)
hist0.AppendBucketWithNDV(&val2Bytes, &val3Bytes, 10, 3, 2)
testData[0].inputHist = hist0
hist1 := NewHistogram(0, 6, 0, 0, types.NewFieldType(mysql.TypeBlob), 0, 0)
hist1.AppendBucketWithNDV(&val0Bytes, &val0Bytes, 0, 0, 0)
hist1.AppendBucketWithNDV(&val1Bytes, &val1Bytes, 0, 0, 0)
hist1.AppendBucketWithNDV(&val2Bytes, &val3Bytes, 0, 0, 0)
testData[1].inputHist = hist1
hist2 := NewHistogram(0, 6, 0, 0, types.NewFieldType(mysql.TypeBlob), 0, 0)
hist2.AppendBucketWithNDV(&val2Bytes, &val3Bytes, 10, 3, 2)
hist2.AppendBucketWithNDV(&val4Bytes, &val4Bytes, 10, 0, 0)
hist2.AppendBucketWithNDV(&val5Bytes, &val5Bytes, 10, 0, 0)
testData[2].inputHist = hist2
hist3 := NewHistogram(0, 6, 0, 0, types.NewFieldType(mysql.TypeBlob), 0, 0)
hist3.AppendBucketWithNDV(&val0Bytes, &val0Bytes, 10, 10, 1)
hist3.AppendBucketWithNDV(&val1Bytes, &val2Bytes, 22, 4, 20)
hist3.AppendBucketWithNDV(&val3Bytes, &val5Bytes, 32, 6, 2)
testData[3].inputHist = hist3
hist4 := NewHistogram(0, 6, 0, 0, types.NewFieldType(mysql.TypeBlob), 0, 0)
hist4.AppendBucketWithNDV(&val0Bytes, &val0Bytes, 0, 0, 0)
hist4.AppendBucketWithNDV(&val1Bytes, &val1Bytes, 0, 0, 0)
hist4.AppendBucketWithNDV(&val2Bytes, &val2Bytes, 10, 3, 2)
hist4.AppendBucketWithNDV(&val3Bytes, &val3Bytes, 10, 0, 0)
hist4.AppendBucketWithNDV(&val4Bytes, &val4Bytes, 10, 0, 0)
hist4.AppendBucketWithNDV(&val5Bytes, &val5Bytes, 20, 3, 2)
hist4.AppendBucketWithNDV(&val6Bytes, &val6Bytes, 30, 3, 2)
testData[4].inputHist = hist4
hist5 := NewHistogram(0, 6, 0, 0, types.NewFieldType(mysql.TypeBlob), 0, 0)
hist5.AppendBucketWithNDV(&val0Bytes, &val0Bytes, 0, 0, 0)
hist5.AppendBucketWithNDV(&val1Bytes, &val1Bytes, 0, 0, 0)
hist5.AppendBucketWithNDV(&val2Bytes, &val2Bytes, 10, 3, 2)
hist5.AppendBucketWithNDV(&val3Bytes, &val3Bytes, 10, 0, 0)
hist5.AppendBucketWithNDV(&val4Bytes, &val4Bytes, 20, 3, 2)
hist5.AppendBucketWithNDV(&val5Bytes, &val5Bytes, 30, 3, 2)
hist5.AppendBucketWithNDV(&val6Bytes, &val6Bytes, 30, 0, 0)
testData[5].inputHist = hist5
// 3. the actual test
for i, test := range testData {
require.Equal(t, test.inputHistToStr, test.inputHist.ToString(1))
test.inputHist.StandardizeForV2AnalyzeIndex()
require.Equal(t, test.outputHistToStr, test.inputHist.ToString(1),
fmt.Sprintf("testData[%d].inputHist:%s", i, test.inputHistToStr))
}
}
func TestNewPseudoHistogramReuseChunk(t *testing.T) {
const (
msgPseudoSameChunk = "pseudo histograms should share the same Bounds chunk"
msgRegularDiffChunks = "regular histograms should have different Bounds chunks"
msgRegularPseudoDiff = "regular and pseudo histograms should have different Bounds chunks"
)
// test that NewPseudoHistogram reuses the same global chunk instance
tp1 := types.NewFieldType(mysql.TypeLonglong)
tp2 := types.NewFieldType(mysql.TypeVarchar)
tp3 := types.NewFieldType(mysql.TypeBlob)
hist1 := NewPseudoHistogram(1, tp1)
hist2 := NewPseudoHistogram(2, tp2)
hist3 := NewPseudoHistogram(3, tp3)
// verify that all pseudo histograms share the same Bounds chunk instance
require.Same(t, hist1.Bounds, hist2.Bounds, msgPseudoSameChunk)
require.Same(t, hist1.Bounds, hist3.Bounds, msgPseudoSameChunk)
require.Same(t, hist2.Bounds, hist3.Bounds, msgPseudoSameChunk)
// verify that regular histograms do NOT share chunks
regularHist1 := NewHistogram(1, 0, 0, 0, tp1, 10, 0)
regularHist2 := NewHistogram(2, 0, 0, 0, tp2, 10, 0)
require.NotSame(t, regularHist1.Bounds, regularHist2.Bounds, msgRegularDiffChunks)
require.NotSame(t, regularHist1.Bounds, hist1.Bounds, msgRegularPseudoDiff)
require.NotSame(t, regularHist2.Bounds, hist1.Bounds, msgRegularPseudoDiff)
// verify that string type field types are properly handled
require.Equal(t, mysql.TypeLonglong, hist1.Tp.GetType())
require.Equal(t, mysql.TypeVarchar, hist2.Tp.GetType())
require.Equal(t, mysql.TypeBlob, hist3.Tp.GetType())
// for string types, collation should be set to binary
require.Equal(t, "binary", hist2.Tp.GetCollate())
require.Equal(t, "binary", hist3.Tp.GetCollate())
}