Hi David, This is exactly the problem that the multi-query optimization project is addressing. Please see the following link for details:
http://wiki.apache.org/pig/PigMultiQueryPerformanceSpecification Thanks, -Richard -----Original Message----- From: David Ciemiewicz (JIRA) [mailto:j...@apache.org] Sent: Tuesday, April 28, 2009 7:43 AM To: pig-dev@hadoop.apache.org Subject: [jira] Commented: (PIG-777) Code refactoring: Create optimization out of store/load post processing code [ https://issues.apache.org/jira/browse/PIG-777?page=com.atlassian.jira.pl ugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12703659#ac tion_12703659 ] David Ciemiewicz commented on PIG-777: -------------------------------------- This seems like it could be useful but I don't understand the full issue as a user. I often want to compute intermediate summaries, store them, and then continue computation. {code}A = load ... ... store D into ... E = group D by ... ... store H into ...{code} The problem I encountered in earlier versions of Pig was that to PREVENT two executions of steps A thru D, I had to introduce a load step before E: {code}A = load ... ... store D into ... D = load ... E = group D by ... ... store H into ...{code} It's great that you will be introducing code that possibly eliminates D = load in the execution. However, is anything being done so that I don't need to introduce D = load in the first place? > Code refactoring: Create optimization out of store/load post processing code > ------------------------------------------------------------------------ ---- > > Key: PIG-777 > URL: https://issues.apache.org/jira/browse/PIG-777 > Project: Pig > Issue Type: Improvement > Reporter: Gunther Hagleitner > > The postProcessing method in the pig server checks whether a logical graph contains stores to and loads from the same location. If so, it will either connect the store and load, or optimize by throwing out the load and connecting the store predecessor with the successor of the load. > Ideally the introduction of the store and load connection should happen in the query compiler, while the optimization should then happen in an separate optimizer step as part of the optimizer framework. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.
