From 3dd594901a4760c170279f6539c4a19eee60205f Mon Sep 17 00:00:00 2001 From: Ti Chi Robot Date: Thu, 17 Aug 2023 16:51:38 +0800 Subject: [PATCH] planner: when pushing `topN` down below `proj`, check whether `topN.ByItems` contains a column(with ID=0) generated by `proj` (#40593) (#41178) close pingcap/tidb#40535 --- planner/core/plan_test.go | 13 +++++++++++++ planner/core/rule_topn_push_down.go | 14 ++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/planner/core/plan_test.go b/planner/core/plan_test.go index b3d23a5f9c692..2e69205a2b9c6 100644 --- a/planner/core/plan_test.go +++ b/planner/core/plan_test.go @@ -25,6 +25,7 @@ import ( "github.com/pingcap/tidb/config" "github.com/pingcap/tidb/expression" "github.com/pingcap/tidb/expression/aggregation" + "github.com/pingcap/tidb/kv" "github.com/pingcap/tidb/parser/ast" "github.com/pingcap/tidb/parser/model" "github.com/pingcap/tidb/parser/mysql" @@ -1151,3 +1152,15 @@ func TestJSONPlanInExplain(t *testing.T) { } } } + +func TestIssue40535(t *testing.T) { + store := testkit.CreateMockStore(t) + var cfg kv.InjectionConfig + tk := testkit.NewTestKit(t, kv.NewInjectedStore(store, &cfg)) + tk.MustExec("use test;") + tk.MustExec("drop table if exists t1; drop table if exists t2;") + tk.MustExec("CREATE TABLE `t1`(`c1` bigint(20) NOT NULL DEFAULT '-2312745469307452950', `c2` datetime DEFAULT '5316-02-03 06:54:49', `c3` tinyblob DEFAULT NULL, PRIMARY KEY (`c1`) /*T![clustered_index] CLUSTERED */) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;") + tk.MustExec("CREATE TABLE `t2`(`c1` set('kn8pu','7et','vekx6','v3','liwrh','q14','1met','nnd5i','5o0','8cz','l') DEFAULT '7et,vekx6,liwrh,q14,1met', `c2` float DEFAULT '1.683167', KEY `k1` (`c2`,`c1`), KEY `k2` (`c2`)) ENGINE=InnoDB DEFAULT CHARSET=gbk COLLATE=gbk_chinese_ci;") + tk.MustExec("(select /*+ agg_to_cop()*/ locate(t1.c3, t1.c3) as r0, t1.c3 as r1 from t1 where not( IsNull(t1.c1)) order by r0,r1) union all (select concat_ws(',', t2.c2, t2.c1) as r0, t2.c1 as r1 from t2 order by r0, r1) order by 1 limit 273;") + require.Empty(t, tk.Session().LastMessage()) +} diff --git a/planner/core/rule_topn_push_down.go b/planner/core/rule_topn_push_down.go index 5dacac7579caa..2b4998049911a 100644 --- a/planner/core/rule_topn_push_down.go +++ b/planner/core/rule_topn_push_down.go @@ -136,6 +136,20 @@ func (p *LogicalProjection) pushDownTopN(topN *LogicalTopN, opt *logicalOptimize topN.ByItems = append(topN.ByItems[:i], topN.ByItems[i+1:]...) } } + + // if topN.ByItems contains a column(with ID=0) generated by projection, projection will prevent the optimizer from pushing topN down. + for _, by := range topN.ByItems { + cols := expression.ExtractColumns(by.Expr) + for _, col := range cols { + if col.ID == 0 && p.Schema().Contains(col) { + // check whether the column is generated by projection + if !p.children[0].Schema().Contains(col) { + p.children[0] = p.children[0].pushDownTopN(nil, opt) + return topN.setChild(p, opt) + } + } + } + } } p.children[0] = p.children[0].pushDownTopN(topN, opt) return p