Re: [ADMIN] concat_ws - Mailing list pgsql-hackers

From Joe Conway
Subject Re: [ADMIN] concat_ws
Date
Msg-id 3F2DB8F0.9040605@joeconway.com
Whole thread Raw
In response to Re: [ADMIN] concat_ws  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> I added code to inline_function to stop inlining if a parameter
> expression to be substituted multiple times has cost greater than
> 10*cpu_operator_cost (which roughly means that it contains more than
> 10 operators or functions).  This seems to cut off the problem nicely,
> at least for this example.  The factor of 10 is a bit of a magic number
> but it seems reasonable.
>

That did it (on fresh copy of cvs):

regression=# explain analyze select

concat_ws('~','01','02','03','04','05','06','07','08','09','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24','25','26','27','28','29','30','31');
                                     QUERY PLAN
----------------------------------------------------------------------------------
  Result  (cost=0.00..0.11 rows=1 width=0) (actual time=2.37..2.37
rows=1 loops=1)
  Total runtime: 2.66 msec
(2 rows)

Thanks Tom!

Joe


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