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https://issues.apache.org/jira/browse/IGNITE-5382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16114290#comment-16114290
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Sergey Kalashnikov commented on IGNITE-5382:
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[~vozerov]
When thread closes its connection or changes schema on it, all the statements
in the thread's statement cache become invalid and we remove them.
Managing both connection and all its statements as a whole seems to be a good
idea becouse of the above.
> SQL: frequent switch between schemas cause severe slowdown
> ----------------------------------------------------------
>
> Key: IGNITE-5382
> URL: https://issues.apache.org/jira/browse/IGNITE-5382
> Project: Ignite
> Issue Type: Task
> Components: cache, sql
> Reporter: Vladimir Ozerov
> Assignee: Sergey Kalashnikov
> Labels: important, performance
> Fix For: 2.2
>
>
> We have thread-bound cached connection to H2 database which is bound to
> specific schema. See {{IgniteH2Indexing.connectionForThread}}.
> When query with different schema is executed, we call {{SET SCHEMA}} command,
> which is rather expensive and may cause slowdown when queries form different
> caches are executed.
> To avoid this we should maintain thread-local map of such connections. Be
> careful with concurrency and resource leaks.
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