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fix sample function #24324

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Merged
mergify merged 5 commits into from
May 10, 2026
Merged

fix sample function #24324

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d7af06e
fix sample function
daviszhen May 9, 2026
c73d09d
fix bvt
daviszhen May 9, 2026
0f7e1a5
fix sca
daviszhen May 9, 2026
9254cf3
Merge branch 'main' into 0509-fix-samp
daviszhen May 9, 2026
027f51d
Merge branch 'main' into 0509-fix-samp
daviszhen May 10, 2026
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25 changes: 15 additions & 10 deletions pkg/sql/colexec/aggexec/vardev2.go
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Original file line number Diff line number Diff line change
Expand Up @@ -220,18 +220,21 @@ func (exec *varStdDevExec[T, A]) Flush() (_ []*vector.Vector, retErr error) {
if exec.IsDistinct() {
for i := range vecs {
for j := 0; j < int(exec.state[i].length); j++ {
if exec.state[i].argCnt[j] == 0 {
if err := vector.AppendNull(vecs[i], exec.mp); err != nil {
return nil, err
cnt := int64(exec.state[i].argCnt[j])
if cnt <= 1 {
// cnt == 1 && exec is samp
if cnt == 0 || !exec.isPop {
if err := vector.AppendNull(vecs[i], exec.mp); err != nil {
return nil, err
}
continue
}
continue
} else if exec.state[i].argCnt[j] == 1 {
z, _ := exec.f2t(0, exec.aggInfo.retType.Scale)
if err := vector.AppendFixed(vecs[i], z, false, exec.mp); err != nil {
return nil, err
}
continue
} else {
cnt := int64(exec.state[i].argCnt[j])
s := float64(0)
s2 := float64(0)
err := exec.state[i].iter(uint16(j), func(k []byte) error {
Expand Down Expand Up @@ -265,10 +268,12 @@ func (exec *varStdDevExec[T, A]) Flush() (_ []*vector.Vector, retErr error) {
sums := vector.MustFixedColNoTypeCheck[float64](exec.state[i].vecs[1])
sumsqs := vector.MustFixedColNoTypeCheck[float64](exec.state[i].vecs[2])
for j, cnt := range cnts {
if cnt == 0 {
vector.AppendNull(vecs[i], exec.mp)
continue
} else if cnt == 1 {
if cnt <= 1 {
// cnt == 1 && exec is samp
if cnt == 0 || !exec.isPop {
vector.AppendNull(vecs[i], exec.mp)
continue
}
z, _ := exec.f2t(0, exec.aggInfo.retType.Scale)
vector.AppendFixed(vecs[i], z, false, exec.mp)
} else {
Expand Down
39 changes: 39 additions & 0 deletions pkg/sql/colexec/aggexec/vardev2_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,45 @@ func TestGetResultVarClampsTinyVarianceToZero(t *testing.T) {
require.Equal(t, 0.0, got)
}

func TestVarSampleSingleNonNullValueReturnsNull(t *testing.T) {
tests := []struct {
name string
isDistinct bool
}{
{
name: "non-distinct",
},
{
name: "distinct",
isDistinct: true,
},
}

for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
mp := mpool.MustNewZero()
param := types.T_int32.ToType()
exec := makeVarSampleExec(mp, 0, tc.isDistinct, param)
require.NoError(t, exec.GroupGrow(1))

v := vector.NewVec(param)
require.NoError(t, vector.AppendFixed(v, int32(4), false, mp))
require.NoError(t, exec.Fill(0, 0, []*vector.Vector{v}))
v.Free(mp)

vecs, err := exec.Flush()
require.NoError(t, err)
require.Len(t, vecs, 1)
require.True(t, vecs[0].IsNull(0))

for _, vec := range vecs {
vec.Free(mp)
}
exec.Free()
})
}
}

func TestNumericToFloat64ViaVarExec(t *testing.T) {
mp := mpool.MustNewZero()

Expand Down
27 changes: 27 additions & 0 deletions test/distributed/cases/function/func_aggr_sample.result
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x) t;
➤ stddev_samp(x)[8,54,0] ¦ var_samp(x)[8,54,0] 𝄀
null ¦ null
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union select 6 as x) t;
➤ stddev_samp(x)[8,54,0] ¦ var_samp(x)[8,54,0] 𝄀
0.7071067811865476 ¦ 0.5
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union select 5 as x) t;
➤ stddev_samp(x)[8,54,0] ¦ var_samp(x)[8,54,0] 𝄀
null ¦ null
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union all select 6 as x) t;
➤ stddev_samp(x)[8,54,0] ¦ var_samp(x)[8,54,0] 𝄀
0.7071067811865476 ¦ 0.5
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union all select 5 as x) t;
➤ stddev_samp(x)[8,54,0] ¦ var_samp(x)[8,54,0] 𝄀
0.0 ¦ 0.0
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union select 6 as x) t;
➤ stddev_samp(distinct x)[8,54,0] ¦ var_samp(distinct x)[8,54,0] 𝄀
0.7071067811865476 ¦ 0.5
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union select 5 as x) t;
➤ stddev_samp(distinct x)[8,54,0] ¦ var_samp(distinct x)[8,54,0] 𝄀
null ¦ null
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union all select 6 as x) t;
➤ stddev_samp(distinct x)[8,54,0] ¦ var_samp(distinct x)[8,54,0] 𝄀
0.7071067811865476 ¦ 0.5
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union all select 5 as x) t;
➤ stddev_samp(distinct x)[8,54,0] ¦ var_samp(distinct x)[8,54,0] 𝄀
null ¦ null
32 changes: 32 additions & 0 deletions test/distributed/cases/function/func_aggr_sample.sql
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Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
-- !!!result below are same as postgresql and mysql
-- !!!
-- input: 5
-- null, null
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x) t;
-- input: 5,6
-- not,not
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union select 6 as x) t;
-- input: 5
-- null, null
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union select 5 as x) t;
-- input: 5,6
-- not,not
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union all select 6 as x) t;
-- input: 5,5
-- not, not
SELECT stddev_samp(x), var_samp(x) FROM (SELECT 5 AS x union all select 5 as x) t;
----------------------
-- Mysql does not support the syntax below
-- input: 5,6
-- not,not
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union select 6 as x) t;
-- input: 5
-- null, null
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union select 5 as x) t;
-- input: 5,6
-- not,not
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union all select 6 as x) t;
-- input: 5
-- not
SELECT stddev_samp(DISTINCT x), var_samp(DISTINCT x) FROM (SELECT 5 AS x union all select 5 as x) t;

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