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Posted to issues@hbase.apache.org by "Vladimir Rodionov (JIRA)" <ji...@apache.org> on 2016/12/19 20:09:58 UTC
[jira] [Comment Edited] (HBASE-17339) Scan-Memory-First
Optimization
[ https://issues.apache.org/jira/browse/HBASE-17339?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15762163#comment-15762163 ]
Vladimir Rodionov edited comment on HBASE-17339 at 12/19/16 8:09 PM:
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This won't work in a general case.
You may have KV in Memory and in store files (different versions). HBase does not give you a guarantee, that memory version is what you ask for (unless you specify exact version).
This can be used only as a hint: If KV is memory give it to me, or MESTORE_FIRST.
was (Author: vrodionov):
I think this won't work in general case.
You may have KV in Memory and in store files (different versions). HBase does not give you a guarantee, that memory version is what you ask for (unless you specify exact version).
This can be used only as a hint: If KV is memory give it to me, or MESTORE_FIRST.
> Scan-Memory-First Optimization
> ------------------------------
>
> Key: HBASE-17339
> URL: https://issues.apache.org/jira/browse/HBASE-17339
> Project: HBase
> Issue Type: Improvement
> Reporter: Eshcar Hillel
> Attachments: HBASE-17339-V01.patch
>
>
> The current implementation of a get operation (to retrieve values for a specific key) scans through all relevant stores of the region; for each store both memory components (memstores segments) and disk components (hfiles) are scanned in parallel.
> We suggest to apply an optimization that speculatively scans memory-only components first and only if the result is incomplete scans both memory and disk.
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