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https://issues.apache.org/jira/browse/KYLIN-4350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17019161#comment-17019161
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weibin0516 commented on KYLIN-4350:
-----------------------------------
Hi, [~seva_ostapenko], not all databases support use databse, such as postgresql
> Pushdown improperly rewrites the query causing it to fail
> ---------------------------------------------------------
>
> Key: KYLIN-4350
> URL: https://issues.apache.org/jira/browse/KYLIN-4350
> Project: Kylin
> Issue Type: Bug
> Components: Query Engine
> Affects Versions: v2.6.4
> Environment: HDP 2.6.5, Kylin 2.6.4, CentOS 7.6
> Reporter: Vsevolod Ostapenko
> Priority: Major
>
> A query that uses WITH clause and is subject for pushdown to Hive (or Impala)
> for execution is incorrectly rewritten before being submitted to the
> execution engine. Table aliases are attributed with database name, with makes
> query invalid.
> Sample log excerpts are below:
>
> {quote}2020-01-17 12:12:21,997 INFO [Query
> e844b846-c589-4729-5a04-483f6d73c834-31163] service.QueryService:404 : The
> original query: with
> t as
> (
> SELECT ZETTICSDW.A_VL_HOURLY_V.IMSIID "ZETTICSDW_A_VL_HOURLY_V_IMSIID",
> ZETTICSDW.A_VL_HOURLY_V.MEDIA_GAP_CALL_ID
> "ZETTICSDW_A_VL_HOURLY_V_MEDIA_GAP_CALL_ID",
> count(*) cnt
> FROM ZETTICSDW.A_VL_HOURLY_V
> WHERE ((ZETTICSDW.A_VL_HOURLY_V.THEDATE = '20200117')
> AND ((ZETTICSDW.A_VL_HOURLY_V.THEHOUR >= '10')
> AND (ZETTICSDW.A_VL_HOURLY_V.THEHOUR <= '10')))
> GROUP BY ZETTICSDW.A_VL_HOURLY_V.IMSIID,
> ZETTICSDW.A_VL_HOURLY_V.MEDIA_GAP_CALL_ID
> )
> select t.ZETTICSDW_A_VL_HOURLY_V_IMSIID,
> count(*) "vl_aggs_model___CD_MEDIA_GAP_CALL_ID"
> *from t*
> group by t.ZETTICSDW_A_VL_HOURLY_V_IMSIID
> ORDER BY "vl_aggs_model___CD_MEDIA_GAP_CALL_ID" desc
> LIMIT 500
> ....
> 2020-01-17 12:12:22,073 INFO [Query
> e844b846-c589-4729-5a04-483f6d73c834-31163]
> adhocquery.AbstractPushdownRunner:37 : the query is converted to with
> t as
> (
> SELECT ZETTICSDW.A_VL_HOURLY_V.IMSIID `ZETTICSDW_A_VL_HOURLY_V_IMSIID`,
> ZETTICSDW.A_VL_HOURLY_V.MEDIA_GAP_CALL_ID
> `ZETTICSDW_A_VL_HOURLY_V_MEDIA_GAP_CALL_ID`,
> count(*) cnt
> FROM ZETTICSDW.A_VL_HOURLY_V
> WHERE ((ZETTICSDW.A_VL_HOURLY_V.THEDATE = '20200117')
> AND ((ZETTICSDW.A_VL_HOURLY_V.THEHOUR >= '10')
> AND (ZETTICSDW.A_VL_HOURLY_V.THEHOUR <= '10')))
> GROUP BY ZETTICSDW.A_VL_HOURLY_V.IMSIID,
> ZETTICSDW.A_VL_HOURLY_V.MEDIA_GAP_CALL_ID
> )
> select t.ZETTICSDW_A_VL_HOURLY_V_IMSIID,
> count(*) `vl_aggs_model___CD_MEDIA_GAP_CALL_ID`
> *{color:#FF0000}from ZETTICSDW.t{color}*
> group by t.ZETTICSDW_A_VL_HOURLY_V_IMSIID
> ORDER BY `vl_aggs_model___CD_MEDIA_GAP_CALL_ID` desc
> LIMIT 500 after applying converter
> org.apache.kylin.source.adhocquery.HivePushDownConverter
> 2020-01-17 12:12:22,108 ERROR [Query
> e844b846-c589-4729-5a04-483f6d73c834-31163] service.QueryService:989 :
> pushdown engine failed current query too
> org.apache.hive.service.cli.HiveSQLException: AnalysisException: Could not
> resolve table reference: '*zetticsdw.t*'
> {quote}
> Pushdown query should be submitted into query engine as written by the user.
> As the best effort Kylin push down executor should issue "use <database>"
> over the same JDBC connection right before submitting the query.
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