[ https://issues.apache.org/jira/browse/CASSANDRA-1902?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
T Jake Luciani reopened CASSANDRA-1902: --------------------------------------- Ok. well It's merged to trunk so we'll keep it there... > Migrate cached pages during compaction > --------------------------------------- > > Key: CASSANDRA-1902 > URL: https://issues.apache.org/jira/browse/CASSANDRA-1902 > Project: Cassandra > Issue Type: Improvement > Components: Core > Affects Versions: 0.7.1 > Reporter: T Jake Luciani > Assignee: T Jake Luciani > Fix For: 0.8 > > Attachments: > 0001-CASSANDRA-1902-cache-migration-impl-with-config-option.txt, > 1902-formatted.txt, 1902-per-column-migration-rebase2.txt, > 1902-per-column-migration.txt, CASSANDRA-1902-v3.patch > > Original Estimate: 32h > Time Spent: 56h > Remaining Estimate: 0h > > Post CASSANDRA-1470 there is an opportunity to migrate cached pages from a > pre-compacted CF during the compaction process. > First, add a method to MmappedSegmentFile: long[] pagesInPageCache() that > uses the posix mincore() function to detect the offsets of pages for this > file currently in page cache. > Then add getActiveKeys() which uses underlying pagesInPageCache() to get the > keys actually in the page cache. > use getActiveKeys() to detect which SSTables being compacted are in the os > cache and make sure the subsequent pages in the new compacted SSTable are > kept in the page cache for these keys. This will minimize the impact of > compacting a "hot" SSTable. > A simpler yet similar approach is described here: > http://insights.oetiker.ch/linux/fadvise/ -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira