no partial (or other) index affecting these results. just a trigger the
outcome of which was affected by the value of that particular boolean.
sorry, should have looked more carefully...
> -----Original Message-----
> From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
> Sent: Tuesday, May 23, 2006 4:00 PM
> To: George Pavlov
> Cc: pgsql-general@postgresql.org
> Subject: Re: [GENERAL] assymetry updating a boolean (=FALSE
> faster than =TRUE)
>
> "George Pavlov" <gpavlov@mynewplace.com> writes:
> > Here is something that seems anomalous to me: when I set a
> boolean field
> > to FALSE performance is much better than when I set it to TRUE. Any
> > reason for FALSE to be favored over TRUE?
>
> It isn't. You're measuring something else than you think you're
> measuring ... maybe a partial index? Varying effects of where the
> free space is in the table? In a test case I see no significant
> difference:
>
> regression=# create table foo(f1 int, f2 bool);
> CREATE TABLE
> regression=# insert into foo select x, true from
> generate_series(1,100000) x;
> INSERT 0 100000
> regression=# \timing
> Timing is on.
> regression=# vacuum foo;
> VACUUM
> Time: 318.153 ms
> regression=# update foo set f2 = true;
> UPDATE 100000
> Time: 2553.014 ms
> regression=# vacuum foo;
> VACUUM
> Time: 410.356 ms
> regression=# update foo set f2 = false;
> UPDATE 100000
> Time: 2453.620 ms
> regression=# vacuum foo;
> VACUUM
> Time: 405.955 ms
> regression=# update foo set f2 = true;
> UPDATE 100000
> Time: 2497.413 ms
> regression=# vacuum foo;
> VACUUM
> Time: 408.403 ms
> regression=# update foo set f2 = false;
> UPDATE 100000
> Time: 2458.824 ms
> regression=#
>
> regards, tom lane
>