Is there a guide anywhere to interpreting the explain command? On Fri, May 7, 2010 at 1:37 PM, Richard Ding (JIRA) <[email protected]> wrote:
> > [ > https://issues.apache.org/jira/browse/PIG-1408?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel] > > Richard Ding updated PIG-1408: > ------------------------------ > > Attachment: PIG-1408.patch > > patch to add aliases to the output plans of the explain command. > > > Annotate explain plans with aliases > > ----------------------------------- > > > > Key: PIG-1408 > > URL: https://issues.apache.org/jira/browse/PIG-1408 > > Project: Pig > > Issue Type: Improvement > > Affects Versions: 0.7.0 > > Reporter: Richard Ding > > Assignee: Richard Ding > > Fix For: 0.8.0 > > > > Attachments: PIG-1408.patch > > > > > > PIG-1156 added aliases in Pig scripts to the corresponding > LogicalOperators and PhysicalOperators. The aliases in the operators, > however, are not displayed in the output created by the explain command. > > Since a Pig script can generate many MR jobs, it will be helpful, for > debugging purposes, to annotate the explain output plans with aliases, so > that users can correlate the jobs with the statements in their scripts. > > Here is an example: given the following script > > {code} > > A = load 'input'; > > B = group A by $0; > > C = foreach B generate group, flatten(A); > > explain C > > {code} > > The output without alias annotation is > > {code} > > MapReduce node 1-28 > > Map Plan > > Local Rearrange[tuple]{bytearray}(false) - 1-22 > > | | > > | Project[bytearray][0] - 1-23 > > | > > |---Load(file:///test/input:org.apache.pig.builtin.PigStorage) - > 1-19-------- > > Reduce Plan > > Store(fakefile:org.apache.pig.builtin.PigStorage) - 1-27 > > | > > |---New For Each(false,true)[bag] - 1-26 > > | | > > | Project[bytearray][0] - 1-24 > > | | > > | Project[bag][1] - 1-25 > > | > > |---Package[tuple]{bytearray} - 1-21-------- > > Global sort: false > > {code} > > > > While the output with alias annotation will be > > {code} > > MapReduce node 1-28 > > Map Plan > > B: Local Rearrange[tuple]{bytearray}(false) - 1-22 > > | | > > | Project[bytearray][0] - 1-23 > > | > > |---A: Load(file:///test/input:org.apache.pig.builtin.PigStorage) - > 1-19-------- > > Reduce Plan > > C: Store(fakefile:org.apache.pig.builtin.PigStorage) - 1-27 > > | > > |---C: New For Each(false,true)[bag] - 1-26 > > | | > > | Project[bytearray][0] - 1-24 > > | | > > | Project[bag][1] - 1-25 > > | > > |---B: Package[tuple]{bytearray} - 1-21-------- > > Global sort: false > > {code} > > -- > This message is automatically generated by JIRA. > - > You can reply to this email to add a comment to the issue online. > >
