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Posted to commits@hbase.apache.org by bu...@apache.org on 2017/04/28 18:34:57 UTC
[2/2] hbase git commit: HBASE-17875 Document why objects over 10MB
are not well-suited for hbase.
HBASE-17875 Document why objects over 10MB are not well-suited for hbase.
Signed-off-by: Sean Busbey <bu...@apache.org>
Project: http://git-wip-us.apache.org/repos/asf/hbase/repo
Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/6edb8f82
Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/6edb8f82
Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/6edb8f82
Branch: refs/heads/master
Commit: 6edb8f82178f1da4b29dc4ee1a1d8ea8dd2484a4
Parents: ba12cdf
Author: Jingcheng Du <ji...@apache.org>
Authored: Fri Apr 28 13:32:30 2017 -0500
Committer: Sean Busbey <bu...@apache.org>
Committed: Fri Apr 28 13:32:30 2017 -0500
----------------------------------------------------------------------
src/main/asciidoc/_chapters/faq.adoc | 3 +++
src/main/asciidoc/_chapters/hbase_mob.adoc | 4 ++--
2 files changed, 5 insertions(+), 2 deletions(-)
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http://git-wip-us.apache.org/repos/asf/hbase/blob/6edb8f82/src/main/asciidoc/_chapters/faq.adoc
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diff --git a/src/main/asciidoc/_chapters/faq.adoc b/src/main/asciidoc/_chapters/faq.adoc
index 7bffe0e..9034d4b 100644
--- a/src/main/asciidoc/_chapters/faq.adoc
+++ b/src/main/asciidoc/_chapters/faq.adoc
@@ -44,6 +44,9 @@ How can I find examples of NoSQL/HBase?::
What is the history of HBase?::
See <<hbase.history,hbase.history>>.
+Why are the cells above 10MB not recommended for HBase?::
+ Large cells don't fit well into HBase's approach to buffering data. First, the large cells bypass the MemStoreLAB when they are written. Then, they cannot be cached in the L2 block cache during read operations. Instead, HBase has to allocate on-heap memory for them each time. This can have a significant impact on the garbage collector within the RegionServer process.
+
=== Upgrading
How do I upgrade Maven-managed projects from HBase 0.94 to HBase 0.96+?::
In HBase 0.96, the project moved to a modular structure. Adjust your project's dependencies to rely upon the `hbase-client` module or another module as appropriate, rather than a single JAR. You can model your Maven dependency after one of the following, depending on your targeted version of HBase. See Section 3.5, \u201cUpgrading from 0.94.x to 0.96.x\u201d or Section 3.3, \u201cUpgrading from 0.96.x to 0.98.x\u201d for more information.
http://git-wip-us.apache.org/repos/asf/hbase/blob/6edb8f82/src/main/asciidoc/_chapters/hbase_mob.adoc
----------------------------------------------------------------------
diff --git a/src/main/asciidoc/_chapters/hbase_mob.adoc b/src/main/asciidoc/_chapters/hbase_mob.adoc
index bdf077a..5da0343 100644
--- a/src/main/asciidoc/_chapters/hbase_mob.adoc
+++ b/src/main/asciidoc/_chapters/hbase_mob.adoc
@@ -36,7 +36,7 @@ read and write paths are optimized for values smaller than 100KB in size. When
HBase deals with large numbers of objects over this threshold, referred to here
as medium objects, or MOBs, performance is degraded due to write amplification
caused by splits and compactions. When using MOBs, ideally your objects will be between
-100KB and 10MB. HBase ***FIX_VERSION_NUMBER*** adds support
+100KB and 10MB (see the <<faq>>). HBase ***FIX_VERSION_NUMBER*** adds support
for better managing large numbers of MOBs while maintaining performance,
consistency, and low operational overhead. MOB support is provided by the work
done in link:https://issues.apache.org/jira/browse/HBASE-11339[HBASE-11339]. To
@@ -155,7 +155,7 @@ family as the second argument. and take a compaction type as the third argument.
----
hbase> compact 't1', 'c1\u2019, \u2018MOB\u2019
-hbase> major_compact_mob 't1', 'c1\u2019, \u2018MOB\u2019
+hbase> major_compact 't1', 'c1\u2019, \u2018MOB\u2019
----
These commands are also available via `Admin.compact` and