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From "Dong Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (KYLIN-2894) Change the query cache expiration strategy by signature checking
Date Sun, 21 Jan 2018 13:34:00 GMT

    [ https://issues.apache.org/jira/browse/KYLIN-2894?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16333518#comment-16333518
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Dong Li commented on KYLIN-2894:
--------------------------------

Hi Yanghong, I see the PR is already submitted. Could you explain more about the signature
here? Thanks!

> Change the query cache expiration strategy by signature checking
> ----------------------------------------------------------------
>
>                 Key: KYLIN-2894
>                 URL: https://issues.apache.org/jira/browse/KYLIN-2894
>             Project: Kylin
>          Issue Type: Sub-task
>          Components: Query Engine
>            Reporter: Zhong Yanghong
>            Assignee: Zhong Yanghong
>            Priority: Major
>
> Currently to invalid query cache, {{CacheService}} will either invoke {{cleanDataCache}}
or {{cleanAllDataCache}}. Both methods will clear all of the query cache, which is very inefficient.
In eBay PROD environment, there's around 400 cubing jobs per day, which means the query cache
will be cleared very 4 minutes. Then we introduced a signature based cache invalidation strategy.
The basic idea is as follows:
> * Add a signature for {{SQLResponse}}, here we choose the cube last build time
> * When fetch {{SQLResponse}} for cache, first check whether the signature is consistent.
If not, this cached value is overdue and will be invalidate.



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