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planner, stats: overflow estimation may lead to wrong join reorder (#56752) (#56766)
close #56704
1 parent 79e0ed6 commit 52b0b58

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4 files changed

+91
-5
lines changed

4 files changed

+91
-5
lines changed

‎pkg/planner/core/rule_join_reorder_greedy.go

Lines changed: 17 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -21,6 +21,7 @@ import (
2121

2222
"github.com/pingcap/tidb/pkg/expression"
2323
"github.com/pingcap/tidb/pkg/planner/core/base"
24+
"github.com/pingcap/tidb/pkg/util/intest"
2425
)
2526

2627
type joinReorderGreedySolver struct {
@@ -97,9 +98,9 @@ func (s *joinReorderGreedySolver) constructConnectedJoinTree(tracer *joinReorder
9798
s.curJoinGroup = s.curJoinGroup[1:]
9899
for {
99100
bestCost := math.MaxFloat64
100-
bestIdx := -1
101-
var finalRemainOthers []expression.Expression
102-
var bestJoin base.LogicalPlan
101+
bestIdx, whateverValidOneIdx := -1, -1
102+
var finalRemainOthers, remainOthersOfWhateverValidOne []expression.Expression
103+
var bestJoin, whateverValidOne base.LogicalPlan
103104
for i, node := range s.curJoinGroup {
104105
newJoin, remainOthers := s.checkConnectionAndMakeJoin(curJoinTree.p, node.p)
105106
if newJoin == nil {
@@ -109,6 +110,9 @@ func (s *joinReorderGreedySolver) constructConnectedJoinTree(tracer *joinReorder
109110
if err != nil {
110111
return nil, err
111112
}
113+
whateverValidOne = newJoin
114+
whateverValidOneIdx = i
115+
remainOthersOfWhateverValidOne = remainOthers
112116
curCost := s.calcJoinCumCost(newJoin, curJoinTree, node)
113117
tracer.appendLogicalJoinCost(newJoin, curCost)
114118
if bestCost > curCost {
@@ -120,7 +124,16 @@ func (s *joinReorderGreedySolver) constructConnectedJoinTree(tracer *joinReorder
120124
}
121125
// If we could find more join node, meaning that the sub connected graph have been totally explored.
122126
if bestJoin == nil {
123-
break
127+
if whateverValidOne == nil {
128+
break
129+
}
130+
// This branch is for the unexpected case.
131+
// We throw assertion in test env. And create a valid join to avoid wrong result in the production env.
132+
intest.Assert(false, "Join reorder should find one valid join but failed.")
133+
bestJoin = whateverValidOne
134+
bestCost = math.MaxFloat64
135+
bestIdx = whateverValidOneIdx
136+
finalRemainOthers = remainOthersOfWhateverValidOne
124137
}
125138
curJoinTree = &jrNode{
126139
p: bestJoin,

‎pkg/statistics/histogram.go

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -67,7 +67,7 @@ type Histogram struct {
6767
// For some types like `Int`, we do not build it because we can get them directly from `Bounds`.
6868
Scalars []scalar
6969
ID int64 // Column ID.
70-
NDV int64 // Number of distinct values.
70+
NDV int64 // Number of distinct values. Note that It contains the NDV of the TopN which is excluded from histogram.
7171
NullCount int64 // Number of null values.
7272
// LastUpdateVersion is the version that this histogram updated last time.
7373
LastUpdateVersion uint64
@@ -980,6 +980,10 @@ func (hg *Histogram) OutOfRangeRowCount(
980980
if histWidth <= 0 {
981981
return 0
982982
}
983+
if math.IsInf(histWidth, 1) {
984+
// The histogram is too wide. As a quick fix, we return 0 to indicate that the overlap percentage is near 0.
985+
return 0
986+
}
983987
boundL := histL - histWidth
984988
boundR := histR + histWidth
985989

‎tests/integrationtest/r/statistics/overflow_calc.result

Lines changed: 61 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,61 @@
1+
CREATE TABLE `lrr_test` ( `COL102` double DEFAULT NULL, `COL1` double GENERATED ALWAYS AS (`COL102` + 10) STORED NOT NULL, PRIMARY KEY (`COL1`) /*T![clustered_index] CLUSTERED */ ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
2+
insert into lrr_test (col102) values(-1.704648925036604e308), (-1.6888619680353582e308), (-1.6685908644498436e308), (-1.6311134967437805e308), (-1.6128280680807152e308), (-1.5899713947158026e308), (-1.5709457594070477e308), (-1.4925714566991343e308), (-1.4705985087370154e308), (-1.4451316666300040e308), (-1.3946576985986583e308), (-1.3695679630646804e308), (-1.3208992137984086e308), (-1.2887981369134862e308), (-1.2119996449796167e308), (-1.195172956104992e308), (-1.1929781068369925e308), (-1.1746351299417647e308), (-1.1237012620945195e308), (-1.1223448185004882e308), (-1.0974439629672084e308), (-1.0657654808610821e308), (-1.0582598945271716e308), (-1.0565276887850733e308), (-1.0416104832981696e308), (-1.0368741532690337e308), (-1.033521479407133e308), (-1.0232269544119505e308), (-9.31943312515408e307), (-9.05107332838438e307), (-8.276443475796885e307), (-7.845086666145396e307), (-7.664543340054255e307), (-7.235369799352141e307), (-7.047280050755922e307), (-6.62205033356235e307), (-6.35964999739255e307), (-5.989391229038818e307), (-5.974526205854541e307), (-5.798684586589338e307), (-4.98047732376121e307), (-4.4623979626128605e307), (-4.3248436443381234e307), (-3.3391152928792773e307), (-3.2694282487729395e307), (-3.2461091065368577e307), (-2.8613054009714654e307), (-2.7176814604572905e307), (-2.1301127705458223e307), (-1.7280065154718344e307), (-1.6743061442642827e307), (-4.862812928655648e306), (-3.3262533560429795e305), (4.124952267435051e305), (5.4576487694211726e306), (1.1237742400537221e307), (1.569984332645614e307), (1.7966188405412235e307), (1.8619233341238355e307), (2.1152066540419881e307), (2.1764927570795164e307), (2.99416682762135e307), (3.0545414962788647e307), (3.262967770716021e307), (3.288944887183685e307), (4.9025219351381e307), (5.250864486081297e307), (5.52054372134351e307), (6.311436996747818e307), (6.870852232080436e307), (7.501871137935436e307), (7.925709054822421e307), (8.438195254661318e307), (8.446731596918706e307), (9.43580947190119e307), (9.66735866233596e307), (1.0022043827847664e308), (1.020869767928594e308), (1.0327408606815872e308), (1.0402383684235906e308), (1.0690255622829305e308), (1.1623306052784659e308), (1.1906116361044565e308), (1.2221839628780758e308), (1.3112927565356536e308), (1.3307364382402157e308), (1.3646958839720612e308), (1.425066345632827e308), (1.4433864261103511e308), (1.5038532858735658e308), (1.5079450808097928e308), (1.553628680980576e308), (1.6241456663280369e308), (1.6295729949930798e308), (1.6328703529666413e308), (1.6832354056195887e308), (1.7017315016390902e308), (1.7134206410400048e308), (1.7240829054261275e308), (1.7257738639648862e308), (1.7262297095455299e308), (1.7905151735809062e308);
3+
analyze table lrr_test;
4+
select t1.col1, t2.col1 from lrr_test as t1 right join lrr_test as t2 on t1.col1 = t2.col1 where t1.col1 >=0 order by t1.col1;
5+
col1 col1
6+
4.124952267435051e305 4.124952267435051e305
7+
5.4576487694211726e306 5.4576487694211726e306
8+
1.1237742400537221e307 1.1237742400537221e307
9+
1.569984332645614e307 1.569984332645614e307
10+
1.7966188405412235e307 1.7966188405412235e307
11+
1.8619233341238355e307 1.8619233341238355e307
12+
2.1152066540419881e307 2.1152066540419881e307
13+
2.1764927570795164e307 2.1764927570795164e307
14+
2.99416682762135e307 2.99416682762135e307
15+
3.0545414962788647e307 3.0545414962788647e307
16+
3.262967770716021e307 3.262967770716021e307
17+
3.288944887183685e307 3.288944887183685e307
18+
4.9025219351381e307 4.9025219351381e307
19+
5.250864486081297e307 5.250864486081297e307
20+
5.52054372134351e307 5.52054372134351e307
21+
6.311436996747818e307 6.311436996747818e307
22+
6.870852232080436e307 6.870852232080436e307
23+
7.501871137935436e307 7.501871137935436e307
24+
7.925709054822421e307 7.925709054822421e307
25+
8.438195254661318e307 8.438195254661318e307
26+
8.446731596918706e307 8.446731596918706e307
27+
9.43580947190119e307 9.43580947190119e307
28+
9.66735866233596e307 9.66735866233596e307
29+
1.0022043827847664e308 1.0022043827847664e308
30+
1.020869767928594e308 1.020869767928594e308
31+
1.0327408606815872e308 1.0327408606815872e308
32+
1.0402383684235906e308 1.0402383684235906e308
33+
1.0690255622829305e308 1.0690255622829305e308
34+
1.1623306052784659e308 1.1623306052784659e308
35+
1.1906116361044565e308 1.1906116361044565e308
36+
1.2221839628780758e308 1.2221839628780758e308
37+
1.3112927565356536e308 1.3112927565356536e308
38+
1.3307364382402157e308 1.3307364382402157e308
39+
1.3646958839720612e308 1.3646958839720612e308
40+
1.425066345632827e308 1.425066345632827e308
41+
1.4433864261103511e308 1.4433864261103511e308
42+
1.5038532858735658e308 1.5038532858735658e308
43+
1.5079450808097928e308 1.5079450808097928e308
44+
1.553628680980576e308 1.553628680980576e308
45+
1.6241456663280369e308 1.6241456663280369e308
46+
1.6295729949930798e308 1.6295729949930798e308
47+
1.6328703529666413e308 1.6328703529666413e308
48+
1.6832354056195887e308 1.6832354056195887e308
49+
1.7017315016390902e308 1.7017315016390902e308
50+
1.7134206410400048e308 1.7134206410400048e308
51+
1.7240829054261275e308 1.7240829054261275e308
52+
1.7257738639648862e308 1.7257738639648862e308
53+
1.7262297095455299e308 1.7262297095455299e308
54+
1.7905151735809062e308 1.7905151735809062e308
55+
explain format='brief' select t1. col1, t2.col1 from lrr_test as t1 right join lrr_test as t2 on t1.col1 = t2.col1 where t1.col1 >=0;
56+
id estRows task access object operator info
57+
MergeJoin 49.00 root inner join, left key:statistics__overflow_calc.lrr_test.col1, right key:statistics__overflow_calc.lrr_test.col1
58+
├─TableReader(Build) 49.00 root data:TableRangeScan
59+
│ └─TableRangeScan 49.00 cop[tikv] table:t2 range:[0,+inf], keep order:true
60+
└─TableReader(Probe) 49.00 root data:TableRangeScan
61+
└─TableRangeScan 49.00 cop[tikv] table:t1 range:[0,+inf], keep order:true

‎tests/integrationtest/t/statistics/overflow_calc.test

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
1+
# https://github.com/pingcap/tidb/issues/56704
2+
CREATE TABLE `lrr_test` ( `COL102` double DEFAULT NULL, `COL1` double GENERATED ALWAYS AS (`COL102` + 10) STORED NOT NULL, PRIMARY KEY (`COL1`) /*T![clustered_index] CLUSTERED */ ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
3+
insert into lrr_test (col102) values(-1.704648925036604e308), (-1.6888619680353582e308), (-1.6685908644498436e308), (-1.6311134967437805e308), (-1.6128280680807152e308), (-1.5899713947158026e308), (-1.5709457594070477e308), (-1.4925714566991343e308), (-1.4705985087370154e308), (-1.4451316666300040e308), (-1.3946576985986583e308), (-1.3695679630646804e308), (-1.3208992137984086e308), (-1.2887981369134862e308), (-1.2119996449796167e308), (-1.195172956104992e308), (-1.1929781068369925e308), (-1.1746351299417647e308), (-1.1237012620945195e308), (-1.1223448185004882e308), (-1.0974439629672084e308), (-1.0657654808610821e308), (-1.0582598945271716e308), (-1.0565276887850733e308), (-1.0416104832981696e308), (-1.0368741532690337e308), (-1.033521479407133e308), (-1.0232269544119505e308), (-9.31943312515408e307), (-9.05107332838438e307), (-8.276443475796885e307), (-7.845086666145396e307), (-7.664543340054255e307), (-7.235369799352141e307), (-7.047280050755922e307), (-6.62205033356235e307), (-6.35964999739255e307), (-5.989391229038818e307), (-5.974526205854541e307), (-5.798684586589338e307), (-4.98047732376121e307), (-4.4623979626128605e307), (-4.3248436443381234e307), (-3.3391152928792773e307), (-3.2694282487729395e307), (-3.2461091065368577e307), (-2.8613054009714654e307), (-2.7176814604572905e307), (-2.1301127705458223e307), (-1.7280065154718344e307), (-1.6743061442642827e307), (-4.862812928655648e306), (-3.3262533560429795e305), (4.124952267435051e305), (5.4576487694211726e306), (1.1237742400537221e307), (1.569984332645614e307), (1.7966188405412235e307), (1.8619233341238355e307), (2.1152066540419881e307), (2.1764927570795164e307), (2.99416682762135e307), (3.0545414962788647e307), (3.262967770716021e307), (3.288944887183685e307), (4.9025219351381e307), (5.250864486081297e307), (5.52054372134351e307), (6.311436996747818e307), (6.870852232080436e307), (7.501871137935436e307), (7.925709054822421e307), (8.438195254661318e307), (8.446731596918706e307), (9.43580947190119e307), (9.66735866233596e307), (1.0022043827847664e308), (1.020869767928594e308), (1.0327408606815872e308), (1.0402383684235906e308), (1.0690255622829305e308), (1.1623306052784659e308), (1.1906116361044565e308), (1.2221839628780758e308), (1.3112927565356536e308), (1.3307364382402157e308), (1.3646958839720612e308), (1.425066345632827e308), (1.4433864261103511e308), (1.5038532858735658e308), (1.5079450808097928e308), (1.553628680980576e308), (1.6241456663280369e308), (1.6295729949930798e308), (1.6328703529666413e308), (1.6832354056195887e308), (1.7017315016390902e308), (1.7134206410400048e308), (1.7240829054261275e308), (1.7257738639648862e308), (1.7262297095455299e308), (1.7905151735809062e308);
4+
5+
analyze table lrr_test;
6+
7+
select t1.col1, t2.col1 from lrr_test as t1 right join lrr_test as t2 on t1.col1 = t2.col1 where t1.col1 >=0 order by t1.col1;
8+
explain format='brief' select t1. col1, t2.col1 from lrr_test as t1 right join lrr_test as t2 on t1.col1 = t2.col1 where t1.col1 >=0;

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