[jira] [Assigned] (IGNITE-6085) SQL: JOIN with multiple conditions is extremely slow
[
https://issues.apache.org/jira/browse/IGNITE-6085?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Roman Kondakov reassigned IGNITE-6085:
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Assignee: (was: Roman Kondakov)
> SQL: JOIN with multiple conditions is extremely slow
>
>
> Key: IGNITE-6085
> URL: https://issues.apache.org/jira/browse/IGNITE-6085
> Project: Ignite
> Issue Type: Task
> Components: sql
>Affects Versions: 2.1
>Reporter: Vladimir Ozerov
>Priority: Major
> Labels: performance
>
> Consider the following query:
> {code}
> SELECT ... FROM A a
> INNER JOIN B b ON b.id = a.foreign_id1 OR b.id = a.foreign_id2
> {code}
> In this case H2 cannot use indexes on {{foreign_id1}} or {{foreign_id2}}
> columns and query execution takes extraordinary time. Known workaround for a
> problem is to apply multiple JOINs, e.g.:
> {code}
> SELECT ... FROM A a
> LEFT OUTER JOIN B b1 ON b1.id = a.foreign_id1
> LEFT OUTER JOIN B b2 ON b2.id = a.foreign_id2
> WHERE b1.id IS NOT NULL AND b2.id IS NOT NULL
> {code}
> On a single real-world scenario it improved exeution time by a factor of 500
> (from 4s to 80ms).
> Something is terribly wrong here. Probably, H2 cannot perform necessary query
> re-write, or cannot understand how to use index. Let's find a way to fix that.
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[jira] [Assigned] (IGNITE-6085) SQL: JOIN with multiple conditions is extremely slow
[
https://issues.apache.org/jira/browse/IGNITE-6085?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Roman Kondakov reassigned IGNITE-6085:
--
Assignee: Roman Kondakov
> SQL: JOIN with multiple conditions is extremely slow
>
>
> Key: IGNITE-6085
> URL: https://issues.apache.org/jira/browse/IGNITE-6085
> Project: Ignite
> Issue Type: Task
> Components: sql
>Affects Versions: 2.1
>Reporter: Vladimir Ozerov
>Assignee: Roman Kondakov
> Labels: performance
> Fix For: 2.4
>
>
> Consider the following query:
> {code}
> SELECT ... FROM A a
> INNER JOIN B b ON b.id = a.foreign_id1 OR b.id = a.foreign_id2
> {code}
> In this case H2 cannot use indexes on {{foreign_id1}} or {{foreign_id2}}
> columns and query execution takes extraordinary time. Known workaround for a
> problem is to apply multiple JOINs, e.g.:
> {code}
> SELECT ... FROM A a
> LEFT OUTER JOIN B b1 ON b1.id = a.foreign_id1
> LEFT OUTER JOIN B b2 ON b2.id = a.foreign_id2
> WHERE b1.id IS NOT NULL AND b2.id IS NOT NULL
> {code}
> On a single real-world scenario it improved exeution time by a factor of 500
> (from 4s to 80ms).
> Something is terribly wrong here. Probably, H2 cannot perform necessary query
> re-write, or cannot understand how to use index. Let's find a way to fix that.
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