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new a2b9b9edd7 [fix](planner) fix bug in agg on constant column (#16442)
a2b9b9edd7 is described below
commit a2b9b9edd72d70fed4cd76c571ee5b736493e3a7
Author: minghong <[email protected]>
AuthorDate: Mon Feb 13 11:26:08 2023 +0800
[fix](planner) fix bug in agg on constant column (#16442)
For performance reason, we want to remove constant column from
groupingExprs.
For example:
`select sum(T.A) from T group by T.B, 'xyz'` is equivalent
to `select sum(T.A) from T group by T.B`
We can remove constant column `abc` from groupingExprs.
But there is an exception when all groupingExpr are constant
For example:
sql1: `select 'abc' from t group by 'abc'`
is not equivalent to
sql2: `select 'abc' from t`
sql3: `select 'abc', sum(a) from t group by 'abc'`
is not equivalent to
sql4: `select 1, sum(a) from t`
(when t is empty, sql3 returns 0 tuple, sql4 return 1 tuple)
We need to keep some constant columns if all groupingExpr are constant.
Consider sql5 `select a from (select "abc" as a, 'def' as b) T group by b,
a;`
if the constant column `a` is in select list, this column should not be
removed.
sql5 is transformed to
sql6 `select a from (select "abc" as a, 'def' as b) T group by a;`
---
.../java/org/apache/doris/analysis/SelectStmt.java | 64 ++++++++++++++++++++--
...antGroupBy_order.out => constant_group_key.out} | 11 +++-
.../sql/group_by/runConstantGroupBy_order.out | 6 ++
.../suites/trino_p0/constant_group_key.groovy | 53 ++++++++++++++++++
.../sql/group_by/runConstantGroupBy_order.sql | 5 +-
5 files changed, 131 insertions(+), 8 deletions(-)
diff --git a/fe/fe-core/src/main/java/org/apache/doris/analysis/SelectStmt.java
b/fe/fe-core/src/main/java/org/apache/doris/analysis/SelectStmt.java
index d0819885db..4b84dd0a86 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/analysis/SelectStmt.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/analysis/SelectStmt.java
@@ -1301,11 +1301,65 @@ public class SelectStmt extends QueryStmt {
substituteOrdinalsAliases(groupingExprs, "GROUP BY", analyzer,
aliasFirst);
if (!groupByClause.isGroupByExtension() &&
!groupingExprs.isEmpty()) {
- ArrayList<Expr> tempExprs = new ArrayList<>(groupingExprs);
- groupingExprs.removeIf(Expr::isConstant);
- if (groupingExprs.isEmpty() && aggExprs.isEmpty()) {
- // should keep at least one expr to make the result correct
- groupingExprs.add(tempExprs.get(0));
+ /*
+ For performance reason, we want to remove constant column from
groupingExprs.
+ For example:
+ `select sum(T.A) from T group by T.B, 'xyz'` is equivalent to
`select sum(T.A) from T group by T.B`
+ We can remove constant column `abc` from groupingExprs.
+
+ But there is an exception when all groupingExpr are constant
+ For example:
+ sql1: `select 'abc' from t group by 'abc'`
+ is not equivalent to
+ sql2: `select 'abc' from t`
+
+ sql3: `select 'abc', sum(a) from t group by 'abc'`
+ is not equivalent to
+ sql4: `select 1, sum(a) from t`
+ (when t is empty, sql3 returns 0 tuple, sql4 return 1 tuple)
+
+ We need to keep some constant columns if all groupingExpr are
constant.
+ Consider sql5 `select a from (select "abc" as a, 'def' as b) T
group by b, a;`
+ if the constant column is in select list, this column should
not be removed.
+ */
+
+ Expr theFirstConstantGroupingExpr = null;
+ boolean someGroupExprRemoved = false;
+ ArrayList<Expr> tempExprs = new ArrayList<>();
+ for (Expr groupExpr : groupingExprs) {
+ //remove groupExpr if it is const, and it is not in select
list
+ boolean removeConstGroupingKey = false;
+ if (groupExpr.isConstant()) {
+ if (theFirstConstantGroupingExpr == null) {
+ theFirstConstantGroupingExpr = groupExpr;
+ }
+ boolean keyInSelectList = false;
+ if (groupExpr instanceof SlotRef) {
+ for (SelectListItem item : selectList.getItems()) {
+ if (item.getExpr() instanceof SlotRef) {
+ keyInSelectList = ((SlotRef)
item.getExpr()).columnEqual(groupExpr);
+ if (keyInSelectList) {
+ break;
+ }
+ }
+ }
+ }
+ removeConstGroupingKey = ! keyInSelectList;
+ }
+ if (removeConstGroupingKey) {
+ someGroupExprRemoved = true;
+ } else {
+ tempExprs.add(groupExpr);
+ }
+ }
+ if (someGroupExprRemoved) {
+ groupingExprs.clear();
+ groupingExprs.addAll(tempExprs);
+ //groupingExprs need at least one expr, it can be
+ //any original grouping expr. we use the first one.
+ if (groupingExprs.isEmpty()) {
+ groupingExprs.add(theFirstConstantGroupingExpr);
+ }
}
}
diff --git
a/regression-test/data/trino_p0/sql/group_by/runConstantGroupBy_order.out
b/regression-test/data/trino_p0/constant_group_key.out
similarity index 55%
copy from
regression-test/data/trino_p0/sql/group_by/runConstantGroupBy_order.out
copy to regression-test/data/trino_p0/constant_group_key.out
index 6a880dbc0a..6cb7d0559c 100644
--- a/regression-test/data/trino_p0/sql/group_by/runConstantGroupBy_order.out
+++ b/regression-test/data/trino_p0/constant_group_key.out
@@ -1,4 +1,11 @@
-- This file is automatically generated. You should know what you did if you
want to edit this
--- !runConstantGroupBy_order --
-2
+-- !scalar_count --
+0
+
+-- !agg_count --
+
+-- !scalar_sum --
+\N
+
+-- !agg_sum --
diff --git
a/regression-test/data/trino_p0/sql/group_by/runConstantGroupBy_order.out
b/regression-test/data/trino_p0/sql/group_by/runConstantGroupBy_order.out
index 6a880dbc0a..7c092acd1e 100644
--- a/regression-test/data/trino_p0/sql/group_by/runConstantGroupBy_order.out
+++ b/regression-test/data/trino_p0/sql/group_by/runConstantGroupBy_order.out
@@ -2,3 +2,9 @@
-- !runConstantGroupBy_order --
2
+-- !runConstantGroupBy_order_2 --
+oneline
+
+-- !runConstantGroupBy_order_3 --
+abc
+
diff --git a/regression-test/suites/trino_p0/constant_group_key.groovy
b/regression-test/suites/trino_p0/constant_group_key.groovy
new file mode 100644
index 0000000000..cd159722a3
--- /dev/null
+++ b/regression-test/suites/trino_p0/constant_group_key.groovy
@@ -0,0 +1,53 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+// This suit test remove constant group_by_key
+suite("constant_group_key") {
+ //remove constant key
+ explain {
+ sql("select 'oneline' from nation group by n_nationkey, 'constant1'")
+ contains "group by: `n_nationkey`"
+ }
+
+ //reserve constant key in group by
+ explain {
+ sql("select 'oneline' from nation group by 'constant1'")
+ contains "group by: 'constant1'"
+ }
+
+ explain {
+ sql("select 'oneline', sum(n_nationkey) from nation group by
'constant1', 'constant2'")
+ contains "group by: 'constant1'"
+ }
+
+ explain {
+ sql("select a from (select '1' as b, 'abc' as a) T group by b, a")
+ contains "group by: 'abc'"
+ }
+
+ sql "drop table if exists cgk_tbl"
+ sql """
+ create table cgk_tbl (a int null)
+ engine=olap duplicate key(a)
+ distributed by hash(a) buckets 1
+ properties ('replication_num'='1');"""
+
+ qt_scalar_count 'select count(*) from cgk_tbl';
+ qt_agg_count "select count(*) from cgk_tbl group by 'any const str'"
+ qt_scalar_sum 'select sum(a) from cgk_tbl';
+ qt_agg_sum "select sum(a) from cgk_tbl group by 'any const str'"
+}
diff --git
a/regression-test/suites/trino_p0/sql/group_by/runConstantGroupBy_order.sql
b/regression-test/suites/trino_p0/sql/group_by/runConstantGroupBy_order.sql
index d90f03a34d..0ed5664054 100644
--- a/regression-test/suites/trino_p0/sql/group_by/runConstantGroupBy_order.sql
+++ b/regression-test/suites/trino_p0/sql/group_by/runConstantGroupBy_order.sql
@@ -1 +1,4 @@
-select 2 from nation group by 1
+select 2 from nation group by 1;
+select "oneline" from nation group by "I am a const, but not to be removed";
+select a from (select "abc" as a, '1' as b) T group by b, a;
+
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