svn commit: r1162612 - /hbase/trunk/src/docbkx/book.xml

[dmeil]

Author: dmeil
Date: Sun Aug 28 23:48:34 2011
New Revision: 1162612

URL: http://svn.apache.org/viewvc?rev=1162612&view=rev
Log:
HBASE-4266 book.xml small change

Modified:
    hbase/trunk/src/docbkx/book.xml

Modified: hbase/trunk/src/docbkx/book.xml
URL: 
http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/book.xml?rev=1162612&r1=1162611&r2=1162612&view=diff
==============================================================================
--- hbase/trunk/src/docbkx/book.xml (original)
+++ hbase/trunk/src/docbkx/book.xml Sun Aug 28 23:48:34 2011
@@ -1663,15 +1663,6 @@ When I build, why do I always get <code>
 <appendix xml:id="hfilev2">
    <title>HFile format version 2</title>
 
-   <appendixinfo>
-           <personname>Mikhail Bautin</personname>
-       <authorgroup>
-           <author><personname>Mikhail Bautin</personname></author>
-           <author><personname>Liyin Tang</personname></author>
-           <author><personname>Kannan Muthukarrupan</personname></author>
-       </authorgroup>
-   </appendixinfo>
-
    <section><title>Motivation </title>
    <para>We found it necessary to revise the HFile format after encountering 
high memory usage and slow startup times caused by large Bloom filters and 
block indexes in the region server. Bloom filters can get as large as 100 MB 
per HFile, which adds up to 2 GB when aggregated over 20 regions. Block indexes 
can grow as large as 6 GB in aggregate size over the same set of regions. A 
region is not considered opened until all of its block index data is loaded. 
Large Bloom filters produce a different performance problem: the first get 
request that requires a Bloom filter lookup will incur the latency of loading 
the entire Bloom filter bit array.</para>
    <para>To speed up region server startup we break Bloom filters and block 
indexes into multiple blocks and write those blocks out as they fill up, which 
also reduces the HFile writer’s memory footprint. In the Bloom filter case, 
“filling up a block” means accumulating enough keys to efficiently utilize 
a fixed-size bit array, and in the block index case we accumulate an “index 
block” of the desired size. Bloom filter blocks and index blocks (we call 
these “inline blocks”) become interspersed with data blocks, and as a side 
effect we can no longer rely on the difference between block offsets to 
determine data block length, as it was done in version 1.</para>