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Re: INNER JOIN ON vs ','+WHERE - Mailing list pgsql-general

From Tom Lane
Subject Re: INNER JOIN ON vs ','+WHERE
Date
Msg-id 16712.993491568@sss.pgh.pa.us
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In response to INNER JOIN ON vs ','+WHERE  ("Thalis A. Kalfigopoulos" <thalis@cs.pitt.edu>)
Responses Re: INNER JOIN ON vs ','+WHERE  ("Thalis A. Kalfigopoulos" <thalis@cs.pitt.edu>)
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"Thalis A. Kalfigopoulos" <thalis@cs.pitt.edu> writes:
> I noticed that doing a join with the INNER JOIN ON... syntax gives a different execution plan (for complex queries at
least)than when using the ',' syntax with the join conditions in the WHERE clause. Actually the latter proved more
efficient:-/ 
> I assume/guess/speculate that the optimizer gets more freedom in the order it'll perform the join when all conditions
arejust thrown in the WHERE clause whereas the former case forces it to follow the user provided join order? 

http://www.ca.postgresql.org/users-lounge/docs/7.1/postgres/explicit-joins.html

            regards, tom lane

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