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HBASE-20299 Update MOB in hbase refguide

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Huaxiang Sun 2018-04-03 13:12:45 -07:00
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commit d9e64aa6b8
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src/main/asciidoc/_chapters/hbase_mob.adoc
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@ -46,6 +46,12 @@ configure the MOB file reader's cache settings for each RegionServer (see
Client code does not need to change to take advantage of HBase MOB support. The Client code does not need to change to take advantage of HBase MOB support. The
feature is transparent to the client. feature is transparent to the client.
MOB compaction
MOB data is flushed into MOB files after MemStore flush. There will be lots of MOB files
after some time. To reduce MOB file count, there is a periodic task which compacts
small MOB files into a large one (MOB compaction).
=== Configuring Columns for MOB === Configuring Columns for MOB
You can configure columns to support MOB during table creation or alteration, You can configure columns to support MOB during table creation or alteration,
@ -75,6 +81,42 @@ hcd.setMobThreshold(102400L);
---- ----
==== ====
=== Configure MOB Compaction Policy
By default, MOB files for one specific day are compacted into one large MOB file.
To reduce MOB file count more, there are other MOB Compaction policies supported.
daily policy - compact MOB Files for one day into one large MOB file (default policy)
weekly policy - compact MOB Files for one week into one large MOB file
montly policy - compact MOB Files for one month into one large MOB File
.Configure MOB compaction policy Using HBase Shell
====
----
hbase> create 't1', {NAME => 'f1', IS_MOB => true, MOB_THRESHOLD => 102400, MOB_COMPACT_PARTITION_POLICY => 'daily'}
hbase> create 't1', {NAME => 'f1', IS_MOB => true, MOB_THRESHOLD => 102400, MOB_COMPACT_PARTITION_POLICY => 'weekly'}
hbase> create 't1', {NAME => 'f1', IS_MOB => true, MOB_THRESHOLD => 102400, MOB_COMPACT_PARTITION_POLICY => 'monthly'}
hbase> alter 't1', {NAME => 'f1', IS_MOB => true, MOB_THRESHOLD => 102400, MOB_COMPACT_PARTITION_POLICY => 'daily'}
hbase> alter 't1', {NAME => 'f1', IS_MOB => true, MOB_THRESHOLD => 102400, MOB_COMPACT_PARTITION_POLICY => 'weekly'}
hbase> alter 't1', {NAME => 'f1', IS_MOB => true, MOB_THRESHOLD => 102400, MOB_COMPACT_PARTITION_POLICY => 'monthly'}
----
====
=== Configure MOB Compaction mergeable threshold
If the size of a mob file is less than this value, it's regarded as a small file and needs to
be merged in mob compaction. The default value is 1280MB.
====
[source,xml]
----
<property>
<name>hbase.mob.compaction.mergeable.threshold</name>
<value>10000000000</value>
</property>
----
====
=== Testing MOB === Testing MOB