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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13202032#comment-13202032
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jirapos...@reviews.apache.org commented on HBASE-4608:
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I tried the compression tool on a log created by YCSB in "load" mode with the
standard dataset. Since the values are fairly large here (100 bytes) it didn't
get a huge compression ratio - from about 64MB down to 52MB (~20%). But still
not bad. I looked at the resulting data using xxd and it looks like there's
still a number of places where we could use variable length integers instead of
non-variable length. I wrote a quick C program to count the number of 0x00
bytes in the log and found about 3MB worth (~5%). Since the actual table data
is all human-readable text in this case, all of the 0x00s should be able to be
compressed away, I think.
I also tested on a YCSB workload where each row has 1000 columns of 4 bytes
each (similar to an indexing workload) and the compression ratio was 60% (64M
down to 25M) with another 4.2MB of 0x00 bytes which could probably be removed.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10650>
invert the order of these || clauses - otherwise you get an out-of-bounds
just running the tool with no arguments
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10651>
I think the better way of expressing this usage would be:
WALCompressor [-u | -c] <input> <output>
-u - uncompresses the input log
-c - compresses the output log
Exactly one of -u or -c must be specified
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10649>
this code doesn't work properly. Here's what you want to do:
Configuration conf = new Configuration();
FileSystem fs = path.getFileSystem(conf);
- Todd
On 2012-01-24 22:29:18, Li Pi wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/2740/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2012-01-24 22:29:18)
bq.
bq.
bq. Review request for hbase, Eli Collins and Todd Lipcon.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. HLog compression. Has unit tests and a command line tool for
compressing/decompressing.
bq.
bq.
bq. This addresses bug HBase-4608.
bq. https://issues.apache.org/jira/browse/HBase-4608
bq.
bq.
bq. Diffs
bq. -----
bq.
bq. src/main/java/org/apache/hadoop/hbase/HConstants.java 8370ef8
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressedKeyValue.java
PRE-CREATION
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressionContext.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java e46a7a0
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java
f067221
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/LRUDictionary.java
PRE-CREATION
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
d9cd6de
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java
cbef70f
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALDictionary.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java
e1117ef
bq.
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLRUDictionary.java
PRE-CREATION
bq.
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java
59910bf
bq.
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplayCompressed.java
PRE-CREATION
bq.
bq. Diff: https://reviews.apache.org/r/2740/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq.
bq. Thanks,
bq.
bq. Li
bq.
bq.
> HLog Compression
> ----------------
>
> Key: HBASE-4608
> URL: https://issues.apache.org/jira/browse/HBASE-4608
> Project: HBase
> Issue Type: New Feature
> Reporter: Li Pi
> Assignee: Li Pi
> Attachments: 4608v1.txt, 4608v5.txt, 4608v6.txt, 4608v7.txt,
> 4608v8fixed.txt
>
>
> The current bottleneck to HBase write speed is replicating the WAL appends
> across different datanodes. We can speed up this process by compressing the
> HLog. Current plan involves using a dictionary to compress table name, region
> id, cf name, and possibly other bits of repeated data. Also, HLog format may
> be changed in other ways to produce a smaller HLog.
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