HBASE-13883 Clarify the MemStore Flush section in the RefGuide
Project: http://git-wip-us.apache.org/repos/asf/hbase/repo Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/fea0dd46 Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/fea0dd46 Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/fea0dd46 Branch: refs/heads/hbase-12439 Commit: fea0dd46dd84b330ecab7addf30276181f8ae7c6 Parents: 61a5ef9 Author: Misty Stanley-Jones <mstanleyjo...@cloudera.com> Authored: Fri Dec 18 11:04:52 2015 -0800 Committer: Misty Stanley-Jones <mstanleyjo...@cloudera.com> Committed: Fri Feb 19 13:42:22 2016 -0800 ---------------------------------------------------------------------- src/main/asciidoc/_chapters/architecture.adoc | 27 ++++++++++++++++------ 1 file changed, 20 insertions(+), 7 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/hbase/blob/fea0dd46/src/main/asciidoc/_chapters/architecture.adoc ---------------------------------------------------------------------- diff --git a/src/main/asciidoc/_chapters/architecture.adoc b/src/main/asciidoc/_chapters/architecture.adoc index 103f624..c469b6f 100644 --- a/src/main/asciidoc/_chapters/architecture.adoc +++ b/src/main/asciidoc/_chapters/architecture.adoc @@ -1509,13 +1509,26 @@ Note that when the flush happens, MemStores that belong to the same region will A MemStore flush can be triggered under any of the conditions listed below. The minimum flush unit is per region, not at individual MemStore level. -. When a MemStore reaches the size specified by `hbase.hregion.memstore.flush.size`, all MemStores that belong to its region will be flushed out to disk. -. When the overall MemStore usage reaches the value specified by `hbase.regionserver.global.memstore.upperLimit`, MemStores from various regions will be flushed out to disk to reduce overall MemStore usage in a RegionServer. - The flush order is based on the descending order of a region's MemStore usage. - Regions will have their MemStores flushed until the overall MemStore usage drops to or slightly below `hbase.regionserver.global.memstore.lowerLimit`. -. When the number of WAL per region server reaches the value specified in `hbase.regionserver.max.logs`, MemStores from various regions will be flushed out to disk to reduce WAL count. - The flush order is based on time. - Regions with the oldest MemStores are flushed first until WAL count drops below `hbase.regionserver.max.logs`. +. When a MemStore reaches the size specified by `hbase.hregion.memstore.flush.size`, + all MemStores that belong to its region will be flushed out to disk. + +. When the overall MemStore usage reaches the value specified by + `hbase.regionserver.global.memstore.upperLimit`, MemStores from various regions + will be flushed out to disk to reduce overall MemStore usage in a RegionServer. ++ +The flush order is based on the descending order of a region's MemStore usage. ++ +Regions will have their MemStores flushed until the overall MemStore usage drops +to or slightly below `hbase.regionserver.global.memstore.lowerLimit`. + +. When the number of WAL log entries in a given region server's WAL reaches the + value specified in `hbase.regionserver.max.logs`, MemStores from various regions + will be flushed out to disk to reduce the number of logs in the WAL. ++ +The flush order is based on time. ++ +Regions with the oldest MemStores are flushed first until WAL count drops below +`hbase.regionserver.max.logs`. [[hregion.scans]] ==== Scans
