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planner: do not remove the first row func if it is a constant | tidb-test=pr/2283 (#50020) #50285

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Merged
merged 2 commits into from
Jan 23, 2024
Merged

planner: do not remove the first row func if it is a constant | tidb-test=pr/2283 (#50020) #50285

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237c488
This is an automated cherry-pick of #50020
0xPoe Jan 10, 2024
84a80cc
fix
0xPoe Jan 23, 2024
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12 changes: 12 additions & 0 deletions executor/executor_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,18 @@ func checkFileName(s string) bool {
return false
}

func TestIssue38756(t *testing.T) {
store := testkit.CreateMockStore(t)
tk := testkit.NewTestKit(t, store)

tk.MustExec("use test")
tk.MustExec("create table t (c1 int)")
tk.MustExec("insert into t values (1), (2), (3)")
tk.MustQuery("SELECT SQRT(1) FROM t").Check(testkit.Rows("1", "1", "1"))
tk.MustQuery("(SELECT DISTINCT SQRT(1) FROM t)").Check(testkit.Rows("1"))
tk.MustQuery("SELECT DISTINCT cast(1 as double) FROM t").Check(testkit.Rows("1"))
}

func TestPessimisticSelectForUpdate(t *testing.T) {
store := testkit.CreateMockStore(t)
tk := testkit.NewTestKit(t, store)
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6 changes: 6 additions & 0 deletions planner/core/task.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1883,6 +1883,12 @@ func RemoveUnnecessaryFirstRow(
// the firstrow in root task can not be removed.
break
}
// Skip if it's a constant.
// For SELECT DISTINCT SQRT(1) FROM t.
// We shouldn't remove the firstrow(SQRT(1)).
if _, ok := gbyExpr.(*expression.Constant); ok {
continue
}
if gbyExpr.Equal(sctx, aggFunc.Args[0]) {
canOptimize = true
firstRowFuncMap[aggFunc].Args[0] = finalGbyItems[j]
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