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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "Hbase/FAQ" by stack
Date Thu, 07 May 2009 04:36:19 GMT
Dear Wiki user,

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The following page has been changed by stack:
http://wiki.apache.org/hadoop/Hbase/FAQ

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  '''7. [[Anchor(7)]] What can I do to improve hbase performance?'''
  
+ See [wiki:PerformanceTuning Performance Tuning] on the wiki home page
- A configuration that can help with random reads at some cost in memory is making the '''hbase.io.index.interval'''
smaller.  By default when hbase writes store files, it adds an entry to the mapfile index
on every 32nd addition (For hadoop, default is every 128th addition).  Adding entries more
frequently -- every 16th or every 8th -- will make it so there is less seeking around looking
for the wanted entry but at the cost of a hbase carrying a larger index (Indices are read
into memory on mapfile open; by default there are one to five or so mapfiles per column family
per region loaded into a regionserver).
- 
- Some basic tests making the '''io.bytes.per.checksum''' larger -- changing it from checksum-checking
every 4096 bytes instead of every 512 bytes -- seem to have no discernible effect on performance.
- 
- A couple of lads report that hbase runs faster when the cluster is balanced; see the balancer
in hadoop, '''./bin/hadoop balancer'''.
- 
- As of hbase 0.19.0, giving hbase more memory for its caches to work with improves performance.
  
  
  '''8. [[Anchor(8)]] How do I access Hbase from my Ruby/Python/Perl/PHP/etc. application?'''
  
+ See [wiki:Hbase HBase non-java access]
+ 
-  * [http://wiki.apache.org/hadoop/Hbase/ThriftApi Description of how to launch a thrift
service, client bindings and examples in ruby and C++] for connecting to Hbase
-  * [http://wiki.apache.org/hadoop/Hbase/HbaseRest REST Interface] to Hbase
-  * [:Hbase/Jython] An example showing how to access HBase from Jython 
-  * [http://github.com/sishen/hbase-ruby Ruby client for Hbase's REST API]
  
  '''9. [[Anchor(9)]] How do I create a table with a column family named "count" (or some
other HQL reserved word)?'''
  
+ Obsolete. No longer applicable.
- Enclose the reserved word in single or double quotes and it should work. If you find an
instance where this fails, please let us know.
- 
- Some example reserved words: count, table, insert select, delete, drop, truncate, where,
row, into
  
  '''10. [[Anchor(10)]] How do cell deletes work?'''
  

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