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From "Taras Ledkov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (IGNITE-6173) SQL: do not start caches on client nodes
Date Thu, 20 Sep 2018 09:32:00 GMT

    [ https://issues.apache.org/jira/browse/IGNITE-6173?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16621725#comment-16621725

Taras Ledkov commented on IGNITE-6173:

[~jooger], my comments:
- please review my minor changes;
- fix javadoc for {{GridCacheProcessor#startLazyCache}}  also try to add more info to differ
{{startLazyCache}} and {{lazyCacheStart}};
- {{QueryUtils#typeForQueryEntity}} what for the {{GridKernalContext ctx}} parameter is added?
Looks like the kernal contexr is always available via {{GridCacheContextInfo}}.
- May {{H2CacheUtils#checkAndInitLazyCache}} be moved to {{H2Utils}}? I cannot see huge semantic
difference between these utility methods.
- Why {{H2TreeNoDataIndex#find}} don't throw {{IgniteSQLException("Shouldn't be invoked")}}?
Is no-data index is really used to fetch data?

> SQL: do not start caches on client nodes
> ----------------------------------------
>                 Key: IGNITE-6173
>                 URL: https://issues.apache.org/jira/browse/IGNITE-6173
>             Project: Ignite
>          Issue Type: Task
>          Components: cache, sql
>    Affects Versions: 2.1
>            Reporter: Vladimir Ozerov
>            Assignee: Yury Gerzhedovich
>            Priority: Major
>              Labels: sql-stability
> When cache is started, this even is distributed through custom discovery message. Server
nodes start the cache, client nodes do nothing until cache is requested explicitly. At the
same time H2 database objects are created only when cache is really started. 
> For this reason query parsing could lead to {{TABLE NOT FOUND}}, {{INDEX NOT FOUND}},
etc. errors. If such exception is observed, we force start of all known cache on a client
and then retry. See {{GridCacheProcessor#createMissingQueryCaches}} method. 
> First, client node cache start leads to another custom discovery message. So query performance
may suffer. Second, this is not needed! We already have all necessary cache info in discovery.

> Let's try to find a way to use available discovery data and do not start cache on a client
for SQL query execution.

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