Yes, I had done UNION. UNION ALL achives the expected plan and speed! Thank
you!
BTW, this is interesting, because there are only about 5 or 6 rows max
returned from both queries - but I guess the planner expects more and hence
changes the plan to remove duplicates.
On Sun, Jul 19, 2009 at 9:05
On Mon, Jul 20, 2009 at 2:22 PM, Robert Jamessrobertja...@gmail.com wrote:
BTW, this is interesting, because there are only about 5 or 6 rows max
returned from both queries - but I guess the planner expects more and hence
changes the plan to remove duplicates.
If you sent the plans for the
Hi. I notice that when I do a WHERE x, Postgres uses an index, and when I
do WHERE y, it does so as well, but when I do WHERE x OR y, it doesn't. Why
is this so? And how can I shut this off?
select * from dict
where
word in (select substr('moon', 0, generate_series(3,length('moon' --
this
PS Running PostgreSQL 8.2.1 on i686-pc-mingw32, compiled by GCC gcc.exe
(GCC) 3.4.2 (mingw-special)
On Sun, Jul 19, 2009 at 6:58 PM, Robert James srobertja...@gmail.comwrote:
Hi. I notice that when I do a WHERE x, Postgres uses an index, and when I
do WHERE y, it does so as well, but when I
On Sun, Jul 19, 2009 at 11:59 PM, Robert Jamessrobertja...@gmail.com wrote:
PS Running PostgreSQL 8.2.1 on i686-pc-mingw32, compiled by GCC gcc.exe
(GCC) 3.4.2 (mingw-special)
On Sun, Jul 19, 2009 at 6:58 PM, Robert James srobertja...@gmail.com
wrote:
Hi. I notice that when I do a WHERE x,
Robert James srobertja...@gmail.com writes:
Hi. I notice that when I do a WHERE x, Postgres uses an index, and when I
do WHERE y, it does so as well, but when I do WHERE x OR y, it
doesn't.
It can use indexes for OR conditions, but not for arbitrary OR
conditions...
select * from dict
Robert James wrote:
Hi. I notice that when I do a WHERE x, Postgres uses an index, and
when I do WHERE y, it does so as well, but when I do WHERE x OR y, it
doesn't. Why is this so? And how can I shut this off?
maybe its because you have no index on (X OR Y) ? or maybe because the
UNION was better, but still 5 times as slow as either query done
individually.
set enable_seqscan=off didn't help at all - it was totally ignored
Is there anything else I can do?
On Sun, Jul 19, 2009 at 7:47 PM, Tom Lane t...@sss.pgh.pa.us wrote:
Robert James srobertja...@gmail.com writes:
Is there anyway to tell Postgres Run these two queries, and union their
results, but don't change the plan as to a UNION - just run them
separately?
Something seems funny to me that running a UNION should be twice as slow as
running the two queries one after the other.
On Sun, Jul 19, 2009 at
On Sun, Jul 19, 2009 at 6:10 PM, Robert Jamessrobertja...@gmail.com wrote:
UNION was better, but still 5 times as slow as either query done
individually.
set enable_seqscan=off didn't help at all - it was totally ignored
Is there anything else I can do?
Did you try union, or union all?
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