[HBASE-8420] Port HBASE-6874 Implement prefetching for scanners from 0.89-fb - ASF JIRA

XML

Word

Printable

JSON

Hadoop Flags:

Reviewed
Release Note:

Hide
By default, prefetching is enabled in the trunk version (0.95.2 and 0.98). To disable it, users have to set prefetching off in the Scan object.

This patch introduced a configuration hbase.hregionserver.prefetcher.resultsize.max to control how much data we can prefetch. By default, it is 256MB. If there is already more than that much data prefetched, no new prefetching will be scheduled until some prefetched results are retrieved by clients, so there is room again for new prefetching.

Show
By default, prefetching is enabled in the trunk version (0.95.2 and 0.98). To disable it, users have to set prefetching off in the Scan object. This patch introduced a configuration hbase.hregionserver.prefetcher.resultsize.max to control how much data we can prefetch. By default, it is 256MB. If there is already more than that much data prefetched, no new prefetching will be scheduled until some prefetched results are retrieved by clients, so there is room again for new prefetching.

This should help scanner performance. We should have it in trunk.

relates to

HBASE-6874 Implement prefetching for scanners

There are no Sub-Tasks for this issue.