what is the size of that index? Have you considered breaking the index into components, ie more than one index on the table? -----Original Message----- From: pgsql-performance-owner@xxxxxxxxxxxxxx [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of Adam Rich Sent: Tuesday, February 06, 2007 8:54 AM To: 'Mark Stosberg'; pgsql-performance@xxxxxxxxxxxxxx Subject: Re: [PERFORM] explain analyze output for review (was: optimizing a geo_distance()...) If I'm reading this correctly, 89% of the query time is spent doing an index scan of earth_coords_idx. Scanning pets is only taking 6% of the total time. -----Original Message----- From: pgsql-performance-owner@xxxxxxxxxxxxxx [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of Mark Stosberg Sent: Tuesday, February 06, 2007 8:40 AM To: pgsql-performance@xxxxxxxxxxxxxx Subject: Re: [PERFORM] explain analyze output for review (was: optimizing a geo_distance()...) Bruno Wolff III wrote: > > Some people here may be able to tell you more if you show us explain > analyze output. Here is my explain analyze output. Some brief context of what's going on. The goal is to find "Pets Near You". We join the pets table on the shelters table to get a zipcode, and then join a shelters table with "earth_distance" to get the coordinates of the zipcode. ( Is there any significant penalty for using a varchar vs an int for a joint? ). I've been investigating partial indexes for the pets table. It has about 300,000 rows, but only about 10 are "active", and those are the ones we are care about. Queries are also frequently made on males vs females, dogs vs cats or specific ages, and those specific cases seem like possible candidates for partial indexes as well. I played with that approach some, but had trouble coming up with any thing that benchmarked faster. I'm reading the explain analyze output correctly myself, nearly all of the time spent is related to the 'pets' table, but I can't see what to about it. Help appreciated! Mark Nested Loop (cost=11.82..29.90 rows=1 width=0) (actual time=37.601..1910.787 rows=628 loops=1) -> Nested Loop (cost=6.68..20.73 rows=1 width=24) (actual time=35.525..166.547 rows=1727 loops=1) -> Bitmap Heap Scan on pets (cost=6.68..14.71 rows=1 width=4) (actual time=35.427..125.594 rows=1727 loops=1) Recheck Cond: (((sex)::text = 'f'::text) AND (species_id = 1)) Filter: ((pet_state)::text = 'available'::text) -> BitmapAnd (cost=6.68..6.68 rows=2 width=0) (actual time=33.398..33.398 rows=0 loops=1) -> Bitmap Index Scan on pets_sex_idx (cost=0.00..3.21 rows=347 width=0) (actual time=14.739..14.739 rows=35579 loops=1) Index Cond: ((sex)::text = 'f'::text) -> Bitmap Index Scan on pet_species_id_idx (cost=0.00..3.21 rows=347 width=0) (actual time=16.779..16.779 rows=48695 loops=1) Index Cond: (species_id = 1) -> Index Scan using shelters_pkey on shelters (cost=0.00..6.01 rows=1 width=28) (actual time=0.012..0.014 rows=1 loops=1727) Index Cond: ("outer".shelter_id = shelters.shelter_id) -> Bitmap Heap Scan on earth_distance (cost=5.14..9.15 rows=1 width=9) (actual time=0.984..0.984 rows=0 loops=1727) Recheck Cond: ((cube_enlarge(('(-2512840.11676572, 4646218.19036629, 3574817.21369166)'::cube)::cube, 160930.130863421::double precision, 3) @ earth_distance.earth_coords) AND (("outer".postal_code_for_joining)::text = (earth_distance.zipcode)::text)) -> BitmapAnd (cost=5.14..5.14 rows=1 width=0) (actual time=0.978..0.978 rows=0 loops=1727) -> Bitmap Index Scan on earth_coords_idx (cost=0.00..2.15 rows=42 width=0) (actual time=0.951..0.951 rows=1223 loops=1727) Index Cond: (cube_enlarge(('(-2512840.11676572, 4646218.19036629, 3574817.21369166)'::cube)::cube, 160930.130863421::double precision, 3) @ earth_coords) -> Bitmap Index Scan on earth_distance_zipcode_idx (cost=0.00..2.74 rows=212 width=0) (actual time=0.015..0.015 rows=1 loops=1727) Index Cond: (("outer".postal_code_for_joining)::text = (earth_distance.zipcode)::text) Total runtime: 1913.099 ms ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq PRIVILEGED AND CONFIDENTIAL This email transmission contains privileged and confidential information intended only for the use of the individual or entity named above. If the reader of the email is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that any use, dissemination or copying of this email transmission is strictly prohibited by the sender. If you have received this transmission in error, please delete the email and immediately notify the sender via the email return address or mailto:postmaster@xxxxxxxxxxxxxxxx Thank you.
