[ http://issues.apache.org/jira/browse/HADOOP-54?page=comments#action_12422077 ] Doug Cutting commented on HADOOP-54: ------------------------------------
> Any way to do this without an extra copy? There's no way to length-prefix things without knowing the length, and the length is only known after the value is serialized. I doubt the extra copy will significantly affect overall write performance. Note that folks who use the raw API, directly passing bytes rather than Writables, should not suffer the extra-copy penalty when adding items to a file. > SequenceFile should compress blocks, not individual entries > ----------------------------------------------------------- > > Key: HADOOP-54 > URL: http://issues.apache.org/jira/browse/HADOOP-54 > Project: Hadoop > Issue Type: Improvement > Components: io > Affects Versions: 0.2.0 > Reporter: Doug Cutting > Assigned To: Arun C Murthy > Fix For: 0.5.0 > > > SequenceFile will optionally compress individual values. But both > compression and performance would be much better if sequences of keys and > values are compressed together. Sync marks should only be placed between > blocks. This will require some changes to MapFile too, so that all file > positions stored there are the positions of blocks, not entries within > blocks. Probably this can be accomplished by adding a > getBlockStartPosition() method to SequenceFile.Writer. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
