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https://issues.apache.org/jira/browse/SPARK-42513?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17700945#comment-17700945
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Yuming Wang commented on SPARK-42513:
-
TiDB:
{code:sql}
create table t1(a int, b int) ;
create table t2(c int, d int) ;
create table t3(e int, f int);
desc select * from t1 left join t2 on a = c left join t3 on a = e order by b
limit 1000;
{code}
{noformat}
mysql> desc select * from t1 left join t2 on a = c left join t3 on a = e order
by b limit 1000;
++--+---+---+-+
| id | estRows | task | access object
| operator info |
++--+---+---+-+
| TopN_17| 1000.00 | root |
| test1.t1.b, offset:0, count:1000|
| └─HashJoin_23 | 1250.00 | root |
| left outer join, equal:[eq(test1.t1.a, test1.t3.e)] |
| ├─TopN_26(Build) | 1000.00 | root |
| test1.t1.b, offset:0, count:1000|
| │ └─HashJoin_32 | 1250.00 | root |
| left outer join, equal:[eq(test1.t1.a, test1.t2.c)] |
| │ ├─TopN_33(Build) | 1000.00 | root |
| test1.t1.b, offset:0, count:1000|
| │ │ └─TableReader_42 | 1000.00 | root |
| data:TopN_41|
| │ │ └─TopN_41| 1000.00 | cop[tikv] |
| test1.t1.b, offset:0, count:1000|
| │ │ └─TableFullScan_40 | 1.00 | cop[tikv] | table:t1
| keep order:false, stats:pseudo |
| │ └─TableReader_47(Probe) | 9990.00 | root |
| data:Selection_46 |
| │ └─Selection_46 | 9990.00 | cop[tikv] |
| not(isnull(test1.t2.c)) |
| │ └─TableFullScan_45 | 1.00 | cop[tikv] | table:t2
| keep order:false, stats:pseudo |
| └─TableReader_50(Probe) | 9990.00 | root |
| data:Selection_49 |
| └─Selection_49 | 9990.00 | cop[tikv] |
| not(isnull(test1.t3.e)) |
| └─TableFullScan_48 | 1.00 | cop[tikv] | table:t3
| keep order:false, stats:pseudo |
++--+---+---+-+
14 rows in set (0.00 sec)
{noformat}
> Push down topK through join
> ---
>
> Key: SPARK-42513
> URL: https://issues.apache.org/jira/browse/SPARK-42513
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 3.4.0
>Reporter: Yuming Wang
>Priority: Major
> Attachments: after-UI.png, before-UI.png
>
>
> {code:scala}
> spark.range(1).selectExpr("id % 1 as a", "id as
> b").write.saveAsTable("t1")
> spark.range(1).selectExpr("id % 1 as x", "id as
> y").write.saveAsTable("t2")
> sql("select * from t1 left join t2 on a = x order by b limit 5").collect()
> spark.sql("set
> spark.sql.optimizer.excludedRules=org.apache.spark.sql.catalyst.optimizer.LimitPushDown")
> sql("select * from t1 left join t2 on a = x order by b limit 5").collect()
> {code}
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