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From "Jan Fernando (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-3439) Query using an RVC based on the base table PK is incorrectly using an index and doing a full scan instead of a point query
Date Sun, 06 Nov 2016 01:11:58 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-3439?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15640883#comment-15640883
] 

Jan Fernando commented on PHOENIX-3439:
---------------------------------------

[~giacomotaylor] Yes via a tenant specific connection. Sorry I wasn't clear.

> Query using an RVC based on the base table PK is incorrectly using an index and doing
a full scan instead of a point query
> --------------------------------------------------------------------------------------------------------------------------
>
>                 Key: PHOENIX-3439
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-3439
>             Project: Phoenix
>          Issue Type: Bug
>    Affects Versions: 4.8.1
>            Reporter: Jan Fernando
>            Assignee: James Taylor
>             Fix For: 4.9.0, 4.8.2
>
>         Attachments: PHOENIX-3439.patch
>
>
> We use Phoenix RVCs to support paginated queries. This performance of this functionality
relies on Phoenix predictably generating scans against a table or index with a PK that matches
the RVC specified for each page.
> What we do is that on the initial query we use PhoenixRuntime.getPkColsDataTypesForSql()
to get the list of PK columns and persist that and use those to generate RVCs for paginated
queries.
> We have discovered that for queries where:
> a) the user doesn't specify an ORDER BY
> b) for tables where secondary indexes are present
> Phoenix returns pk cols for the base table via getPkColsDataTypesForSql() but then subsequent
queries using the RVCs to paginate execute against a secondary index doing a full scan.
> We have a table with a secondary index where this is an issue. The base table has a PK
of PKCOL1, PKCOL2, PKCOL3 and 
> PKCOL4. We have an immutable secondary index where the PK is PKCOL1, PKCOL3, PKCOL2,
PKCOL4.
> Here's what happens:
> Here is our query we run to get the Query plan from which we generate the RVCs to be
used for paging:
> EXPLAIN SELECT pkcol1, pkcol2, pkcol3, pkcol4, col1, col2
> FROM MY_TABLES."MYTABLE"
> LIMIT 501;
> I get the following explain:
> CLIENT 6-CHUNK SERIAL 1-WAY ROUND ROBIN RANGE SCAN OVER MY_TABLES.MY_TABLE ['00Dxx0000001gFA']
> SERVER 501 ROW LIMIT
> CLIENT 501 ROW LIMIT
> Therefore the columns we record for RVCs for paging are PK1, PK2, PK3, PK4 from MY_TABLES.MY_TABLE
> However when I generate the RVC query to page through the data:
> EXPLAIN SELECT pkcol1, pkcol2, pkcol3, pkcol4, col1, col2
> FROM MY_TABLES."MYTABLE"
> (pkcol1, pkcol2, pkcol3,pkcol4) > ('001','001xx000003DHml',to_date('2015-10-21 09
(tel:2015102109):50:55.0'),'017xx0000022FuI')
> LIMIT 501;
> I get the follow explain plan:
> CLIENT 24-CHUNK 7811766 ROWS 6291457403 BYTES PARALLEL 1-WAY ROUND ROBIN RANGE SCAN OVER
MY_TABLES.MY_SECONDARY_INDEX ['00Dxx0000001gFA','001'] - ['00Dxx0000001gFA',*]
> SERVER FILTER BY ("PKCOL1", "PKCOL2, "PKCOL3", "PKCOL4") > (TO_CHAR('001'), TO_CHAR('001xx000003DHml'),
DATE '2015-10-21 09 (tel:2015102109):50:55.000', TO_CHAR('017xx0000022FuI'))
> SERVER 501 ROW LIMIT
> CLIENT 501 ROW LIMIT
> We expected that the second query with RVCs above would execute against the base table
as the base table PK is PKCOL1, PKCOL2, PKCOL3, PKCOL4 and the index PK is PKCOL1, PKCOL3,
PKCOL2, PKCOL4.



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