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Re: MergeJoin beats HashJoin in the case of multiple hash clauses - Mailing list pgsql-hackers

From Tender Wang
Subject Re: MergeJoin beats HashJoin in the case of multiple hash clauses
Date
Msg-id CAHewXNnA+5sjiZTF+4nEDNM1F-+2yP+1cpqZXwUkm6uwmPUW0w@mail.gmail.com
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In response to Re: MergeJoin beats HashJoin in the case of multiple hash clauses  (Alexander Korotkov <aekorotkov@gmail.com>)
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Hi,

While I debug hashjoin codes,  in estimate_multivariate_bucketsize(), I find that
the list_copy(hashclauses) below is unnecessary if we have a single join clause.

List       *clauses = list_copy(hashclauses);
...

I adjust the place of list_copy() call as the attached patch.
This can save some overhead of function calls and memory copies.

Any thoughts?
 
--
Thanks, Tender Wang
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