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planner: process over-optimization and skip plan-cache in some cases to avoid disaster plans #38537

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merged 5 commits into from
Oct 20, 2022
Merged

planner: process over-optimization and skip plan-cache in some cases to avoid disaster plans #38537

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836f8a4
fixup
qw4990 Oct 19, 2022
0be9238
fixup
qw4990 Oct 19, 2022
8be0344
Merge branch 'master' into fix-38533
qw4990 Oct 19, 2022
d43b0e8
fixup
qw4990 Oct 19, 2022
afdd2e2
Merge branch 'master' into fix-38533
ti-chi-bot Oct 20, 2022
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2 changes: 1 addition & 1 deletion executor/explainfor_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -864,7 +864,7 @@ func TestIndexMerge4PlanCache(t *testing.T) {
tk.MustExec("set @a=9, @b=10, @c=11;")
tk.MustQuery("execute stmt using @a, @a;").Check(testkit.Rows("10 10 10"))
tk.MustQuery("execute stmt using @a, @c;").Check(testkit.Rows("10 10 10", "11 11 11"))
tk.MustQuery("select @@last_plan_from_cache;").Check(testkit.Rows("1"))
tk.MustQuery("select @@last_plan_from_cache;").Check(testkit.Rows("0")) // a>=9 and a<=9 --> a=9
tk.MustQuery("execute stmt using @c, @a;").Check(testkit.Rows("10 10 10"))
tk.MustQuery("select @@last_plan_from_cache;").Check(testkit.Rows("1"))

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19 changes: 19 additions & 0 deletions planner/core/plan_cache_test.go
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Expand Up @@ -130,3 +130,22 @@ func TestIssue38269(t *testing.T) {
rows := tk.MustQuery(fmt.Sprintf("explain for connection %d", tkProcess.ID)).Rows()
require.Contains(t, rows[6][4], "range: decided by [eq(test.t2.a, test.t1.a) in(test.t2.b, 40, 50, 60)]")
}

func TestIssue38533(t *testing.T) {
store := testkit.CreateMockStore(t)
tk := testkit.NewTestKit(t, store)
tk.MustExec("use test")
tk.MustExec("create table t (a int, key (a))")
tk.MustExec(`prepare st from "select /*+ use_index(t, a) */ a from t where a=? and a=?"`)
tk.MustExec(`set @a=1`)
tk.MustExec(`execute st using @a, @a`)
tkProcess := tk.Session().ShowProcess()
ps := []*util.ProcessInfo{tkProcess}
tk.Session().SetSessionManager(&testkit.MockSessionManager{PS: ps})
plan := tk.MustQuery(fmt.Sprintf("explain for connection %d", tkProcess.ID)).Rows()
require.True(t, strings.Contains(plan[1][0].(string), "RangeScan")) // range-scan instead of full-scan

tk.MustExec(`execute st using @a, @a`)
tk.MustExec(`execute st using @a, @a`)
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
}
17 changes: 7 additions & 10 deletions planner/core/prepare_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1420,7 +1420,7 @@ func TestIssue29303(t *testing.T) {
tk.MustQuery(`execute stmt using @a,@b,@c,@d`).Check(testkit.Rows())
tk.MustExec(`set @a="龂", @b="龂", @c="龂", @d="龂"`)
tk.MustQuery(`execute stmt using @a,@b,@c,@d`).Check(testkit.Rows("� 龂 � 龂"))
tk.MustQuery(`select @@last_plan_from_cache`).Check(testkit.Rows("0"))
tk.MustQuery(`select @@last_plan_from_cache`).Check(testkit.Rows("1"))
}

func TestIssue34725(t *testing.T) {
Expand Down Expand Up @@ -1946,11 +1946,10 @@ func TestPlanCachePointGetAndTableDual(t *testing.T) {
tk.MustExec("insert into t1 values('0000','7777',1)")
tk.MustExec("prepare s1 from 'select * from t1 where c1=? and c2>=? and c2<=?'")
tk.MustExec("set @a1='0000', @b1='9999'")
// IndexLookup plan would be built, we should cache it.
tk.MustQuery("execute s1 using @a1, @b1, @b1").Check(testkit.Rows())
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
tk.MustQuery("execute s1 using @a1, @a1, @b1").Check(testkit.Rows("0000 7777 1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0")) // c2>=9999 and c2<=9999 --> c2=9999

tk.MustExec("create table t2(c1 bigint(20) primary key, c2 varchar(20))")
tk.MustExec("insert into t2 values(1,'7777')")
Expand All @@ -1966,17 +1965,15 @@ func TestPlanCachePointGetAndTableDual(t *testing.T) {
tk.MustExec("insert into t3 values(2,1,1)")
tk.MustExec("prepare s3 from 'select /*+ use_index_merge(t3) */ * from t3 where (c1 >= ? and c1 <= ?) or c2 > 1'")
tk.MustExec("set @a3=1,@b3=3")
// TableReader plan would be built, we should cache it.
tk.MustQuery("execute s3 using @a3,@a3").Check(testkit.Rows())
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
tk.MustQuery("execute s3 using @a3,@b3").Check(testkit.Rows("2 1 1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0")) // c1>=1 and c1<=1 --> c1==1

tk.MustExec("prepare s3 from 'select /*+ use_index_merge(t3) */ * from t3 where (c1 >= ? and c1 <= ?) or c2 > 1'")
tk.MustExec("set @a3=1,@b3=3")
// TableReader plan would be built, we should cache it.
tk.MustQuery("execute s3 using @b3,@a3").Check(testkit.Rows())
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
tk.MustQuery("execute s3 using @a3,@b3").Check(testkit.Rows("2 1 1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))

Expand All @@ -1987,7 +1984,7 @@ func TestPlanCachePointGetAndTableDual(t *testing.T) {
tk.MustQuery("execute s4 using @a4,@a4").Check(testkit.Rows())
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
tk.MustQuery("execute s4 using @a4,@b4").Check(testkit.Rows("2 1 1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0")) // c1>=3 and c1<=3 --> c1=3

tk.MustExec("prepare s4 from 'select /*+ use_index_merge(t4) */ * from t4 where (c1 >= ? and c1 <= ?) or c2 > 1'")
tk.MustExec("set @a4=1,@b4=3")
Expand Down Expand Up @@ -2044,7 +2041,7 @@ func TestIssue23671(t *testing.T) {
tk.MustQuery("execute s1 using @a, @b, @c").Check(testkit.Rows("1 1"))
tk.MustExec("set @a=1, @b=1, @c=10")
tk.MustQuery("execute s1 using @a, @b, @c").Check(testkit.Rows("1 1", "2 2"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0")) // b>=1 and b<=1 --> b=1
}

func TestIssue29296(t *testing.T) {
Expand Down Expand Up @@ -2550,7 +2547,7 @@ func TestCachedTable(t *testing.T) {
// IndexLookup
tk.MustQuery("execute indexLookup using @a, @b").Check(testkit.Rows("2"))
require.True(t, lastReadFromCache(tk))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0")) // b>1 and b<3 --> b=2

// PointGet
tk.MustQuery("execute pointGet using @a").Check(testkit.Rows("1"))
Expand Down
4 changes: 2 additions & 2 deletions util/ranger/detacher.go
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Expand Up @@ -619,8 +619,8 @@ func ExtractEqAndInCondition(sctx sessionctx.Context, conditions []expression.Ex
columnValues[i] = &valueInfo{mutable: true}
}
if expression.MaybeOverOptimized4PlanCache(sctx, conditions) {
// TODO: optimize it more elaborately, e.g. return [2 3, 2 3] as accesses for 'where a = 2 and b = 3 and c >= ? and c <= ?'
return nil, conditions, nil, nil, false
// `a=@x and a=@y` --> `a=@x if @x==@y`
sctx.GetSessionVars().StmtCtx.SkipPlanCache = true
}
}
}
Expand Down