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opt: fix issue with dangling pointer in statisticsBuilder #37983

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Jun 6, 2019
Merged

opt: fix issue with dangling pointer in statisticsBuilder #37983

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4 changes: 4 additions & 0 deletions pkg/sql/opt/memo/statistics_builder.go
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Original file line number Diff line number Diff line change
Expand Up @@ -386,6 +386,8 @@ func (sb *statisticsBuilder) colStatLeaf(
colStat.NullCount = s.RowCount * unknownNullCountRatio
} else {
colStatLeaf := sb.colStatLeaf(nullableCols, s, fd, notNullCols)
// Fetch the colStat again since it may now have a different address.
colStat, _ = s.ColStats.Lookup(colSet)
colStat.NullCount = colStatLeaf.NullCount
}
}
Expand Down Expand Up @@ -414,6 +416,8 @@ func (sb *statisticsBuilder) colStatLeaf(
nullCount += colStatLeaf.NullCount * (1 - nullCount/s.RowCount)
}
})
// Fetch the colStat again since it may now have a different address.
colStat, _ = s.ColStats.Lookup(colSet)
colStat.DistinctCount = min(distinctCount, s.RowCount)
colStat.NullCount = min(nullCount, s.RowCount)
}
Expand Down
92 changes: 92 additions & 0 deletions pkg/sql/opt/memo/testdata/stats/scan
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Original file line number Diff line number Diff line change
Expand Up @@ -522,3 +522,95 @@ scan a
├── stats: [rows=10]
├── key: (1)
└── ordering: +1

# Regression test for #37953.
exec-ddl
CREATE TABLE t37953 (
a UUID NOT NULL,
b FLOAT8 NOT NULL,
c TIME NOT NULL,
d UUID NOT NULL,
e VARCHAR,
f "char" NULL,
g INT4 NOT NULL,
h VARCHAR NULL,
i REGPROC NULL,
j FLOAT8 NOT NULL
)
----
TABLE t37953
├── a uuid not null
├── b float not null
├── c time not null
├── d uuid not null
├── e varchar
├── f "char"
├── g int4 not null
├── h varchar
├── i regproc
├── j float not null
├── rowid int not null (hidden)
└── INDEX primary
└── rowid int not null (hidden)

norm
WITH
subq (col0, col1)
AS (
SELECT
tab1.g AS col0,
CASE
WHEN ilike_escape(
regexp_replace(
tab0.h,
tab1.e,
tab0.f,
tab0.e::STRING
),
tab1.f,
''
)
THEN true
ELSE false
END
AS col1
FROM
t37953 AS tab0, t37953 AS tab1
WHERE
tab0.j IN (tab1.j,)
)
SELECT
1
FROM
subq
WHERE
subq.col1;
----
project
├── columns: "?column?":24(int!null)
├── stats: [rows=0.95099005]
├── fd: ()-->(24)
├── select
│ ├── columns: col1:23(bool!null)
│ ├── stats: [rows=0.95099005, distinct(23)=0.95099005, null(23)=0]
│ ├── fd: ()-->(23)
│ ├── project
│ │ ├── columns: col1:23(bool)
│ │ ├── stats: [rows=333333.333, distinct(23)=333333.333, null(23)=16336.65]
│ │ ├── inner-join
│ │ │ ├── columns: tab0.e:5(varchar) tab0.f:6("char") tab0.h:8(varchar) tab0.j:10(float!null) tab1.e:16(varchar) tab1.f:17("char") tab1.j:21(float!null)
│ │ │ ├── stats: [rows=333333.333, distinct(10)=100, null(10)=0, distinct(21)=100, null(21)=0, distinct(5,6,8,16,17)=333333.333, null(5,6,8,16,17)=16336.65]
│ │ │ ├── scan tab0
│ │ │ │ ├── columns: tab0.e:5(varchar) tab0.f:6("char") tab0.h:8(varchar) tab0.j:10(float!null)
│ │ │ │ └── stats: [rows=1000, distinct(10)=100, null(10)=0, distinct(5,6,8)=1000, null(5,6,8)=29.701]
│ │ │ ├── scan tab1
│ │ │ │ ├── columns: tab1.e:16(varchar) tab1.f:17("char") tab1.j:21(float!null)
│ │ │ │ └── stats: [rows=1000, distinct(21)=100, null(21)=0, distinct(16,17)=1000, null(16,17)=19.9]
│ │ │ └── filters
│ │ │ └── tab0.j IN (tab1.j,) [type=bool, outer=(10,21)]
│ │ └── projections
│ │ └── CASE WHEN ilike_escape(regexp_replace(tab0.h, tab1.e, tab0.f, tab0.e::STRING), tab1.f, '') THEN true ELSE false END [type=bool, outer=(5,6,8,16,17)]
│ └── filters
│ └── variable: col1 [type=bool, outer=(23), constraints=(/23: [/true - /true]; tight), fd=()-->(23)]
└── projections
└── const: 1 [type=int]
12 changes: 12 additions & 0 deletions pkg/sql/opt/props/col_stats_map.go
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,10 @@ func (m *ColStatsMap) Count() int {

// Get returns the nth statistic in the map, by its ordinal position. This
// position is stable across calls to Get or Add (but not RemoveIntersecting).
// NOTE: The returned *ColumnStatistic is only valid until this ColStatsMap is
// updated via a call to Add() or RemoveIntersecting(). At that point,
// the address of the statistic may have changed, so it must be fetched
// again using another call to Get() or Lookup().
func (m *ColStatsMap) Get(nth int) *ColumnStatistic {
if nth < initialColStatsCap {
return &m.initial[nth]
Expand All @@ -107,6 +111,10 @@ func (m *ColStatsMap) Get(nth int) *ColumnStatistic {

// Lookup returns the column statistic indexed by the given column set. If no
// such statistic exists in the map, then ok=false.
// NOTE: The returned *ColumnStatistic is only valid until this ColStatsMap is
// updated via a call to Add() or RemoveIntersecting(). At that point,
// the address of the statistic may have changed, so it must be fetched
// again using another call to Lookup() or Get().
func (m *ColStatsMap) Lookup(cols opt.ColSet) (colStat *ColumnStatistic, ok bool) {
// Scan the inlined statistics if there are only a few statistics in the map.
if m.count <= initialColStatsCap {
Expand Down Expand Up @@ -150,6 +158,10 @@ func (m *ColStatsMap) Lookup(cols opt.ColSet) (colStat *ColumnStatistic, ok bool
// it does not yet exist in the map, then Add adds a new blank ColumnStatistic
// and returns it, along with added=true. Otherwise, Add returns the existing
// ColumnStatistic with added=false.
// NOTE: The returned *ColumnStatistic is only valid until this ColStatsMap is
// updated via another call to Add() or RemoveIntersecting(). At that
// point, the address of the statistic may have changed, so it must be
// fetched again using Lookup() or Get().
func (m *ColStatsMap) Add(cols opt.ColSet) (_ *ColumnStatistic, added bool) {
// Only add column set if it is not already present in the map.
colStat, ok := m.Lookup(cols)
Expand Down