What does PPA use to compare?

Document ID : KB000012452
Last Modified Date : 14/02/2018
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Question:

What does the compare process use to compare SQL to a previous version?  Does it use the statement number or the text of the SQL or some other info? How do complex joins get evaluated?  How sensitive Plan Analyzer is to what changes in a program?                                                                                                 

                                                                            

Answer:

1. Basically PPA compares Explain SQL by matching the STMTNO. Obviously it tries to do exact matching first, then if that fails it does a 'proximity' check and looks up & down the chain of stmts looking for a similarly structured statemen within the general proximity of the original. But essentially everything start with the 2 lists (before & after) sorted by stmt number, and so the comparison works best if the ordering of the sql within the program remains unchanged    

 

2- No, PPA does not take advantage of the  QUERYNO when doing a compare.