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https://issues.apache.org/jira/browse/FLINK-30396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17693587#comment-17693587
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lincoln lee commented on FLINK-30396:
-------------------------------------
fixed in master: a72f88f36505e1ce45f2280584a11385c2c2bc14
> sql hint 'LOOKUP' which is defined in outer query block may take effect in
> inner query block
> --------------------------------------------------------------------------------------------
>
> Key: FLINK-30396
> URL: https://issues.apache.org/jira/browse/FLINK-30396
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / Planner
> Affects Versions: 1.16.0
> Reporter: Jianhui Dong
> Assignee: Jianhui Dong
> Priority: Major
> Labels: pull-request-available
>
> As [flink
> doc|https://nightlies.apache.org/flink/flink-docs-master/docs/dev/table/sql/queries/hints/#query-hints]
> said:
> > {{Query hints}} can be used to suggest the optimizer to affect query
> > execution plan within a specified query scope. Their effective scope is
> > current {{{}Query block{}}}([What are query blocks
> > ?|https://nightlies.apache.org/flink/flink-docs-master/docs/dev/table/sql/queries/hints/#what-are-query-blocks-])
> > which {{Query Hints}} are specified.
> But the sql hint 'LOOKUP' behaves differently like the demo following:
> {code:java}
> -- DDL
> CREATE TABLE left_table (
> lid INTEGER,
> lname VARCHAR,
> pts AS PROCTIME()
> ) WITH (
> 'connector' = 'filesystem',
> 'format' = 'csv',
> 'path'='xxx'
> )
> CREATE TABLE dim_table (
> id INTEGER,
> name VARCHAR,
> mentor VARCHAR,
> gender VARCHAR
> ) WITH (
> 'connector' = 'jdbc',
> 'url' = 'xxx',
> 'table-name' = 'dim1',
> 'username' = 'xxx',
> 'password' = 'xxx',
> 'driver'= 'com.mysql.cj.jdbc.Driver'
> )
> -- DML
> SELECT /*+ LOOKUP('table'='outer') */
> ll.id AS lid,
> ll.name,
> r.mentor,
> r.gender
> FROM (
> SELECT /*+ LOOKUP('table'='inner') */
> l.lid AS id,
> l.lname AS name,
> r.mentor,
> r.gender,
> l.pts
> FROM left_table AS l
> JOIN dim_table FOR SYSTEM_TIME AS OF l.pts AS r
> ON l.lname = r.name
> ) ll JOIN dim_table FOR SYSTEM_TIME AS OF ll.pts AS r ON ll.name=r.name{code}
> The inner correlate will have two hints:
> {noformat}
> {
> [LOOKUP inheritPath:[0] options:{table=inner}],
> [LOOKUP inheritPath:[0, 0, 0] options:{table=outer}]
> }{noformat}
> and IMO which maybe is a bug.
> The first hint comes from the inner query block and the second hint comes
> from the outer block, and ClearJoinHintWithInvalidPropagationShuttle will not
> clear the second hint cause the correlate has no 'ALIAS' hint.
> The reason for the above case is that the hint 'ALIAS' now only works for
> join rel nodes and 'LOOKUP' works for correlate and join rel nodes.
> I think maybe the better way would be to make 'ALIAS' support both correlate
> and join rel nodes like 'LOOKUP'.
>
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