Disable Block Cache On Compactions
----------------------------------
Key: HBASE-3976
URL: https://issues.apache.org/jira/browse/HBASE-3976
Project: HBase
Issue Type: Improvement
Components: regionserver
Affects Versions: 0.90.3
Reporter: Karthick Sankarachary
Assignee: Karthick Sankarachary
Priority: Minor
Fix For: 0.90.4
Is there a good reason to believe that caching blocks during compactions is
beneficial? Currently, if block cache is enabled on a certain family, then
every time it's compacted, we load all of its blocks into the (LRU) cache, at
the expense of the legitimately hot ones.
As a matter of fact, this concern was raised earlier in HBASE-1597, which
rightly points out that, "we should not bog down the LRU with unneccessary
blocks" during compaction. Even though that issue has been marked as "fixed",
it looks like it ought to be reopened.
Should we err on the side of caution and not cache blocks during compactions
period (as illustrated in the attached patch)? Or, can we be selectively
aggressive about what blocks do get cached during compaction (e.g., only cache
those blocks from the recent files)?
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
