Thread: indexes are fucked
Hi all,
I got another problem with postgres. This time it
refuses to use the indexes. Check this out:
siam_production=> \d render
Table
"public.render"
Column | Type |
Modifiers
----------------------+-----------------------------+--------------------------------------------------------
id | integer |
not null default nextval('public.render_id_seq'::text)
shot_id | integer |
not null
process | character(3) |
not null
person_id | integer |
not null
session_xml | text |
not null
guts_snapshot_id | integer |
layer | text |
render_path | text |
not null
frames | text |
not null
shot_index | integer |
not null
timestamp | timestamp without time zone |
not null default now()
layer_render_version | integer |
num_frames | integer |
mean_render_time | integer |
stdev_render_time | integer |
min_render_time | integer |
max_render_time | integer |
failed_frames | text |
swapped_frames | text |
killed_frames | text |
status | character varying(10) |
render_settings | text |
explicit_guts_log | text |
completed_frames | integer |
priority | character varying(3) |
render_host | character varying(10) |
Indexes: render_pkey primary key btree (id),
render_person_id_idx btree (person_id),
render_shot_id_idx btree (shot_id)
Foreign Key constraints: $3 FOREIGN KEY
(guts_snapshot_id) REFERENCES shot_snapshot(id) ON
UPDATE CASCADE ON DELETE RESTRICT DEFERRABLE INITIALLY
DEFERRED,
$2 FOREIGN KEY (process)
REFERENCES process_enum(code) ON UPDATE CASCADE ON
DELETE RESTRICT DEFERRABLE INITIALLY DEFERRED,
$1 FOREIGN KEY (shot_id)
REFERENCES shot(id) ON UPDATE CASCADE ON DELETE
RESTRICT DEFERRABLE INITIALLY DEFERRED
siam_production=> explain SELECT render.* FROM render
WHERE person_id = 432;
QUERY PLAN
-----------------------------------------------------------------
Seq Scan on render (cost=0.00..39014.72 rows=27833
width=1493)
Filter: (person_id = 432)
(2 rows)
siam_production=>
As you can see, there is an index on render.person_id,
but postgres is using sequential scan. I have tried
*repeatedly* to reindex, analyze, drop & create index,
vacuum, etc. to no avail. What is wrong? I need this
fixed ASAP. It's killing the performance.
btw, the same thing would happen to
render_shot_id_idx, but after repeatedly doing
reindex, alanyze, vacuum, drop & create index, etc. it
suddenly started to work.
Eugene
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On Tue, 2005-08-02 at 10:04 -0700, Dr NoName wrote: > I got another problem with postgres. This time it > refuses to use the indexes. Check this out: [snip] > siam_production=> explain SELECT render.* FROM render > WHERE person_id = 432; > QUERY PLAN > ----------------------------------------------------------------- > Seq Scan on render (cost=0.00..39014.72 rows=27833 > width=1493) > Filter: (person_id = 432) An explain analyze would be more informative, with and without seqscan enabled. What proportion of rows have this particular value of person_id? Maybe you need to increase statistics target of the column. What is the output of these: set enable_seqscan = off; explain SELECT render.* FROM render WHERE person_id = 432; set enable_seqscan = on; explain SELECT render.* FROM render WHERE person_id = 432; select count(*) from render; select count(*) from render WHERE person_id = 432; gnari
On Tue, 2005-08-02 at 12:04, Dr NoName wrote:
> Hi all,
>
> I got another problem with postgres. This time it
> refuses to use the indexes. Check this out:
>
>
> siam_production=> \d render
> Table
> "public.render"
> Column | Type |
> Modifiers
> ----------------------+-----------------------------+--------------------------------------------------------
> id | integer |
> not null default nextval('public.render_id_seq'::text)
> shot_id | integer |
> not null
> process | character(3) |
> not null
> person_id | integer |
> not null
> session_xml | text |
> not null
> guts_snapshot_id | integer |
> layer | text |
> render_path | text |
> not null
> frames | text |
> not null
> shot_index | integer |
> not null
> timestamp | timestamp without time zone |
> not null default now()
> layer_render_version | integer |
> num_frames | integer |
> mean_render_time | integer |
> stdev_render_time | integer |
> min_render_time | integer |
> max_render_time | integer |
> failed_frames | text |
> swapped_frames | text |
> killed_frames | text |
> status | character varying(10) |
> render_settings | text |
> explicit_guts_log | text |
> completed_frames | integer |
> priority | character varying(3) |
> render_host | character varying(10) |
> Indexes: render_pkey primary key btree (id),
> render_person_id_idx btree (person_id),
> render_shot_id_idx btree (shot_id)
> Foreign Key constraints: $3 FOREIGN KEY
> (guts_snapshot_id) REFERENCES shot_snapshot(id) ON
> UPDATE CASCADE ON DELETE RESTRICT DEFERRABLE INITIALLY
> DEFERRED,
> $2 FOREIGN KEY (process)
> REFERENCES process_enum(code) ON UPDATE CASCADE ON
> DELETE RESTRICT DEFERRABLE INITIALLY DEFERRED,
> $1 FOREIGN KEY (shot_id)
> REFERENCES shot(id) ON UPDATE CASCADE ON DELETE
> RESTRICT DEFERRABLE INITIALLY DEFERRED
>
> siam_production=> explain SELECT render.* FROM render
> WHERE person_id = 432;
> QUERY PLAN
> -----------------------------------------------------------------
> Seq Scan on render (cost=0.00..39014.72 rows=27833
> width=1493)
> Filter: (person_id = 432)
> (2 rows)
>
> siam_production=>
>
>
> As you can see, there is an index on render.person_id,
> but postgres is using sequential scan. I have tried
> *repeatedly* to reindex, analyze, drop & create index,
> vacuum, etc. to no avail. What is wrong? I need this
> fixed ASAP. It's killing the performance.
>
> btw, the same thing would happen to
> render_shot_id_idx, but after repeatedly doing
> reindex, alanyze, vacuum, drop & create index, etc. it
> suddenly started to work.
1: Please refrain from the f word. There are some kids in schools (not
university) reading this list. there's really no need.
Please post the output of
explain analyze <yourqueryhere>
> What is the output of these:
>
> set enable_seqscan = off;
> explain SELECT render.* FROM render WHERE person_id
> = 432;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------
Index Scan using render_person_id_idx on render
(cost=0.00..108735.88 rows=27833 width=1493) (actual
time=0.11..77.62 rows=5261 loops=1)
Index Cond: (person_id = 432)
Total runtime: 80.99 msec
(3 rows)
so it will use the index if I disable seq scan? wtf?
> set enable_seqscan = on;
> explain SELECT render.* FROM render WHERE person_id
> = 432;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------
Seq Scan on render (cost=0.00..39014.72 rows=27833
width=1493) (actual time=7.11..743.55 rows=5261
loops=1)
Filter: (person_id = 432)
Total runtime: 747.42 msec
(3 rows)
> select count(*) from render;
count
--------
236612
(1 row)
> select count(*) from render WHERE person_id = 432;
count
-------
5261
(1 row)
thanks,
Eugene
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This is really the only thing I can think to suggest;
Have you tried 'SET enable_seqscan TO OFF;' and then tried the query
again? This happens to me now and then where an index is a lot faster
but the planner just doesn't want to use it. I've got an option in my
code to turn off 'enable_seqscan', perform the query, and turn in back
on for problem queries.
I'm still pretty new though so defer to anyone else's suggestions.
HTH
Madison
Dr NoName wrote:
> Hi all,
>
> I got another problem with postgres. This time it
> refuses to use the indexes. Check this out:
>
>
> siam_production=> \d render
> Table
> "public.render"
> Column | Type |
> Modifiers
> ----------------------+-----------------------------+--------------------------------------------------------
> id | integer |
> not null default nextval('public.render_id_seq'::text)
> shot_id | integer |
> not null
> process | character(3) |
> not null
> person_id | integer |
> not null
> session_xml | text |
> not null
> guts_snapshot_id | integer |
> layer | text |
> render_path | text |
> not null
> frames | text |
> not null
> shot_index | integer |
> not null
> timestamp | timestamp without time zone |
> not null default now()
> layer_render_version | integer |
> num_frames | integer |
> mean_render_time | integer |
> stdev_render_time | integer |
> min_render_time | integer |
> max_render_time | integer |
> failed_frames | text |
> swapped_frames | text |
> killed_frames | text |
> status | character varying(10) |
> render_settings | text |
> explicit_guts_log | text |
> completed_frames | integer |
> priority | character varying(3) |
> render_host | character varying(10) |
> Indexes: render_pkey primary key btree (id),
> render_person_id_idx btree (person_id),
> render_shot_id_idx btree (shot_id)
> Foreign Key constraints: $3 FOREIGN KEY
> (guts_snapshot_id) REFERENCES shot_snapshot(id) ON
> UPDATE CASCADE ON DELETE RESTRICT DEFERRABLE INITIALLY
> DEFERRED,
> $2 FOREIGN KEY (process)
> REFERENCES process_enum(code) ON UPDATE CASCADE ON
> DELETE RESTRICT DEFERRABLE INITIALLY DEFERRED,
> $1 FOREIGN KEY (shot_id)
> REFERENCES shot(id) ON UPDATE CASCADE ON DELETE
> RESTRICT DEFERRABLE INITIALLY DEFERRED
>
> siam_production=> explain SELECT render.* FROM render
> WHERE person_id = 432;
> QUERY PLAN
> -----------------------------------------------------------------
> Seq Scan on render (cost=0.00..39014.72 rows=27833
> width=1493)
> Filter: (person_id = 432)
> (2 rows)
>
> siam_production=>
>
>
> As you can see, there is an index on render.person_id,
> but postgres is using sequential scan. I have tried
> *repeatedly* to reindex, analyze, drop & create index,
> vacuum, etc. to no avail. What is wrong? I need this
> fixed ASAP. It's killing the performance.
>
> btw, the same thing would happen to
> render_shot_id_idx, but after repeatedly doing
> reindex, alanyze, vacuum, drop & create index, etc. it
> suddenly started to work.
>
> Eugene
>
> __________________________________________________
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> Tired of spam? Yahoo! Mail has the best spam protection around
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-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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TLE-BU, The Linux Experience; Back Up
http://tle-bu.org
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siam_production=> explain analyze select * from render
where person_id = 432;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------
Seq Scan on render (cost=0.00..39014.72 rows=27833
width=1493) (actual time=7.11..743.55 rows=5261
loops=1)
Filter: (person_id = 432)
Total runtime: 747.42 msec
(3 rows)
thanks,
Eugene
--- Scott Marlowe <smarlowe@g2switchworks.com> wrote:
> On Tue, 2005-08-02 at 12:04, Dr NoName wrote:
> > Hi all,
> >
> > I got another problem with postgres. This time it
> > refuses to use the indexes. Check this out:
> >
> >
> > siam_production=> \d render
> > Table
> > "public.render"
> > Column | Type
> |
> > Modifiers
> >
>
----------------------+-----------------------------+--------------------------------------------------------
> > id | integer
> |
> > not null default
> nextval('public.render_id_seq'::text)
> > shot_id | integer
> |
> > not null
> > process | character(3)
> |
> > not null
> > person_id | integer
> |
> > not null
> > session_xml | text
> |
> > not null
> > guts_snapshot_id | integer
> |
> > layer | text
> |
> > render_path | text
> |
> > not null
> > frames | text
> |
> > not null
> > shot_index | integer
> |
> > not null
> > timestamp | timestamp without time
> zone |
> > not null default now()
> > layer_render_version | integer
> |
> > num_frames | integer
> |
> > mean_render_time | integer
> |
> > stdev_render_time | integer
> |
> > min_render_time | integer
> |
> > max_render_time | integer
> |
> > failed_frames | text
> |
> > swapped_frames | text
> |
> > killed_frames | text
> |
> > status | character varying(10)
> |
> > render_settings | text
> |
> > explicit_guts_log | text
> |
> > completed_frames | integer
> |
> > priority | character varying(3)
> |
> > render_host | character varying(10)
> |
> > Indexes: render_pkey primary key btree (id),
> > render_person_id_idx btree (person_id),
> > render_shot_id_idx btree (shot_id)
> > Foreign Key constraints: $3 FOREIGN KEY
> > (guts_snapshot_id) REFERENCES shot_snapshot(id) ON
> > UPDATE CASCADE ON DELETE RESTRICT DEFERRABLE
> INITIALLY
> > DEFERRED,
> > $2 FOREIGN KEY (process)
> > REFERENCES process_enum(code) ON UPDATE CASCADE ON
> > DELETE RESTRICT DEFERRABLE INITIALLY DEFERRED,
> > $1 FOREIGN KEY (shot_id)
> > REFERENCES shot(id) ON UPDATE CASCADE ON DELETE
> > RESTRICT DEFERRABLE INITIALLY DEFERRED
> >
> > siam_production=> explain SELECT render.* FROM
> render
> > WHERE person_id = 432;
> > QUERY PLAN
> >
>
-----------------------------------------------------------------
> > Seq Scan on render (cost=0.00..39014.72
> rows=27833
> > width=1493)
> > Filter: (person_id = 432)
> > (2 rows)
> >
> > siam_production=>
> >
> >
> > As you can see, there is an index on
> render.person_id,
> > but postgres is using sequential scan. I have
> tried
> > *repeatedly* to reindex, analyze, drop & create
> index,
> > vacuum, etc. to no avail. What is wrong? I need
> this
> > fixed ASAP. It's killing the performance.
> >
> > btw, the same thing would happen to
> > render_shot_id_idx, but after repeatedly doing
> > reindex, alanyze, vacuum, drop & create index,
> etc. it
> > suddenly started to work.
>
> 1: Please refrain from the f word. There are some
> kids in schools (not
> university) reading this list. there's really no
> need.
>
> Please post the output of
>
> explain analyze <yourqueryhere>
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 5: don't forget to increase your free space map
> settings
>
____________________________________________________
Start your day with Yahoo! - make it your home page
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On Tue, 2005-08-02 at 10:50 -0700, Dr NoName wrote: > > What is the output of these: > > > > set enable_seqscan = off; > > explain SELECT render.* FROM render WHERE person_id > > = 432; > > > QUERY PLAN > ------------------------------------------------------------------------------------------------------------------------------------------- > Index Scan using render_person_id_idx on render > (cost=0.00..108735.88 rows=27833 width=1493) (actual > time=0.11..77.62 rows=5261 loops=1) > Index Cond: (person_id = 432) > Total runtime: 80.99 msec > (3 rows) > > > so it will use the index if I disable seq scan? wtf? Setting enable_seqscan to off artificially adds a high fake cost factor to seqscans, so the planner will not use them, unless there is no alternative. This usually should not be done in production, but can be useful for debugging. Here we see that the planner estimated 27833 rows, but actually only 5261 rows were retrieved. Based on the high number of rows, a cost of 108735 was estimated. > > > > set enable_seqscan = on; > > explain SELECT render.* FROM render WHERE person_id > > = 432; > > QUERY PLAN > -------------------------------------------------------------------------------------------------------------- > Seq Scan on render (cost=0.00..39014.72 rows=27833 > width=1493) (actual time=7.11..743.55 rows=5261 > loops=1) > Filter: (person_id = 432) > Total runtime: 747.42 msec > (3 rows) the seqscan is cheaper when a large enough proportion (maybe 5%) of rows are retrieved, and indeed the cost is estimated at 39014 try to increase statistics for this column: ALTER TABLE render ALTER COLUMN person_id SET STATISTICS 1000; ANALYZE render; 1000 is the maximum value, and probably overkill, but you might start with that. If this helps, you can try to lower values until you find the lowest one that still suits your data. Usually, 200 is enough. gnari
On Tue, 2005-08-02 at 13:05, Dr NoName wrote: > siam_production=> explain analyze select * from render > where person_id = 432; > > QUERY PLAN > -------------------------------------------------------------------------------------------------------------- > Seq Scan on render (cost=0.00..39014.72 rows=27833 > width=1493) (actual time=7.11..743.55 rows=5261 > loops=1) > Filter: (person_id = 432) > Total runtime: 747.42 msec > (3 rows) Notice the disparity here? The query planner thinks that there's gonna be 27833 rows returned, but there's only really 5261 being returned. When's the last time you analyzed this table? And have you considered running the pg_autovacuum daemon, which will vacuum and analyze for you in the back ground?
> the seqscan is cheaper when a large enough > proportion > (maybe 5%) of rows are retrieved, and indeed the > cost > is estimated at 39014 very good explanation. thank you. > try to increase statistics for this column: > > ALTER TABLE render ALTER COLUMN person_id > SET STATISTICS 1000; > ANALYZE render; > > 1000 is the maximum value, and probably overkill, > but you might start with that. If this helps, you > can > try to lower values until you find the lowest one > that still suits your data. Usually, 200 is enough. ok, we're getting into voodoo territory. What is this "statistics"? How can I see what the current value is? How can I estimate what's a "good" value? Where can I find more information about this? thanks, Eugene __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
> When's the last time you analyzed this table? And a few hours before I posted this. vacuumdb --analyze also runs every night. > have you considered > running the pg_autovacuum daemon, which will vacuum > and analyze for you > in the back ground? We are using postgresql 7.3.2 which doesn't have autovacuum. Eugene __________________________________ Yahoo! Mail for Mobile Take Yahoo! Mail with you! Check email on your mobile phone. http://mobile.yahoo.com/learn/mail
On Tue, 2005-08-02 at 13:26, Dr NoName wrote: > > When's the last time you analyzed this table? And > > a few hours before I posted this. vacuumdb --analyze > also runs every night. Were there a lot of updates / deletes between when you ran analyze and when you ran this query? If so, you might want to schedule more frequent analyze runs and / or include them in whatever script is doing the udpating / deleting. Also, you might want to look at tuning your database. I've found that on machines that can cache most of their data sets, adjusting things like effective_cache_size and random_page_cost makes a big difference. > > have you considered > > running the pg_autovacuum daemon, which will vacuum > > and analyze for you > > in the back ground? > > We are using postgresql 7.3.2 which doesn't have > autovacuum. Sad. I think you can use the pg_autovacuum from 7.4 on 7.3 though I've not tried it. Also, 7.3.2 it QUITE out of date. you should, at a minimum, be running 7.3.10. It's a straigh ahead, in place upgrade, and I'm certain there were bug fixes from 7.3.2 to 7.3.10 that you wouldn't want to run without. You might want to schedule analyzes to run every thirty minutes or every hour.
On Tue, Aug 02, 2005 at 01:41:48PM -0500, Scott Marlowe wrote: > Also, you might want to look at tuning your database. I've found that > on machines that can cache most of their data sets, adjusting things > like effective_cache_size and random_page_cost makes a big difference. Also, as Ragnar Hafstað suggested, consider increasing the statistics target on the column in question. The row estimate (27833) was over five times higher than the actual number of rows (5261), resulting in an overinflated cost estimate for an index scan. Increasing the statistics should help the planner make a more accurate estimate. Here are some useful links: http://www.postgresql.org/docs/7.3/static/performance-tips.html#USING-EXPLAIN http://www.postgresql.org/docs/7.3/static/planner-stats.html http://developer.postgresql.org/docs/postgres/planner-stats-details.html The last link will be in the documentation for 8.1 when it's released, but I think it largely applies to earlier versions as well. -- Michael Fuhr http://www.fuhr.org/~mfuhr/
Thanks Ragnar. That solved the problem. I still would like some explanation about this voodoo. Most importantly, how can I estimage a "good" statistics number? thanks, Eugene --- Dr NoName <spamacct11@yahoo.com> wrote: > > the seqscan is cheaper when a large enough > > proportion > > (maybe 5%) of rows are retrieved, and indeed the > > cost > > is estimated at 39014 > > very good explanation. thank you. > > > > try to increase statistics for this column: > > > > ALTER TABLE render ALTER COLUMN person_id > > SET STATISTICS 1000; > > ANALYZE render; > > > > 1000 is the maximum value, and probably overkill, > > but you might start with that. If this helps, you > > can > > try to lower values until you find the lowest one > > that still suits your data. Usually, 200 is > enough. > > > ok, we're getting into voodoo territory. What is > this > "statistics"? How can I see what the current value > is? > How can I estimate what's a "good" value? Where can > I > find more information about this? > > thanks, > > Eugene > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam > protection around > http://mail.yahoo.com > > ---------------------------(end of > broadcast)--------------------------- > TIP 9: In versions below 8.0, the planner will > ignore your desire to > choose an index scan if your joining column's > datatypes do not > match > ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs
On 8/2/05, Dr NoName <spamacct11@yahoo.com> wrote: > Thanks Ragnar. That solved the problem. I still would > like some explanation about this voodoo. Most > importantly, how can I estimage a "good" statistics > number? > > thanks, > > Eugene http://www.postgresql.org/docs/8.0/static/planner-stats.html -- regards, Jaime Casanova (DBA: DataBase Aniquilator ;)
Language reflects the character of those who use it. In this case, the language used also reflects on the community to which it is directed. I don't wish to be associated with a "professional" community, such as Postgre, that holds such shallow values. Bob Pawley ----- Original Message ----- From: "Jaime Casanova" <systemguards@gmail.com> To: "Dr NoName" <spamacct11@yahoo.com> Cc: "Ragnar Hafstað" <gnari@simnet.is>; <pgsql-general@postgresql.org> Sent: Tuesday, August 02, 2005 12:57 PM Subject: Re: [GENERAL] indexes are fucked On 8/2/05, Dr NoName <spamacct11@yahoo.com> wrote: > Thanks Ragnar. That solved the problem. I still would > like some explanation about this voodoo. Most > importantly, how can I estimage a "good" statistics > number? > > thanks, > > Eugene http://www.postgresql.org/docs/8.0/static/planner-stats.html -- regards, Jaime Casanova (DBA: DataBase Aniquilator ;) ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@postgresql.org so that your message can get through to the mailing list cleanly
Bob Pawley wrote: > Language reflects the character of those who use it. > > In this case, the language used also reflects on the community to which > it is directed. > > I don't wish to be associated with a "professional" community, such as > Postgre, that holds such shallow values. Well since there is no Postgre community I guess this isn't a problem... I assume you are speaking to the colorful four letter word in the subject. It would not have been my choice either and in general if you review the lists you will see that swearing is rare. However if you are not going to associate with a community because one person chose to use a word you don't like then you are going to lead a very lonely life. Have you ever grepped for four letter words in Linux? We are an Open Source community, we embrace many values. Some people value things a little differently than others. Sincerely, Joshua D. Drake > > Bob Pawley > > > ----- Original Message ----- From: "Jaime Casanova" > <systemguards@gmail.com> > To: "Dr NoName" <spamacct11@yahoo.com> > Cc: "Ragnar Hafstað" <gnari@simnet.is>; <pgsql-general@postgresql.org> > Sent: Tuesday, August 02, 2005 12:57 PM > Subject: Re: [GENERAL] indexes are fucked > > > On 8/2/05, Dr NoName <spamacct11@yahoo.com> wrote: > >> Thanks Ragnar. That solved the problem. I still would >> like some explanation about this voodoo. Most >> importantly, how can I estimage a "good" statistics >> number? >> >> thanks, >> >> Eugene > > > http://www.postgresql.org/docs/8.0/static/planner-stats.html > -- Your PostgreSQL solutions company - Command Prompt, Inc. 1.800.492.2240 PostgreSQL Replication, Consulting, Custom Programming, 24x7 support Managed Services, Shared and Dedicated Hosting Co-Authors: plPHP, plPerlNG - http://www.commandprompt.com/
On Tue, 2005-08-02 at 15:52, Joshua D. Drake wrote: > Bob Pawley wrote: > > Language reflects the character of those who use it. > > > > In this case, the language used also reflects on the community to which > > it is directed. > > > > I don't wish to be associated with a "professional" community, such as > > Postgre, that holds such shallow values. > > Well since there is no Postgre community I guess this isn't a problem... > > I assume you are speaking to the colorful four letter word in the > subject. It would not have been my choice either and in general if you > review the lists you will see that swearing is rare. > > However if you are not going to associate with a community because one > person chose to use a word you don't like then you are going to lead a > very lonely life. > > Have you ever grepped for four letter words in Linux? > > We are an Open Source community, we embrace many values. Some people > value things a little differently than others. > > Sincerely, > > Joshua D. Drake What I found most interesting about his reply was that he couldn't be bothered to take 5 whole seconds to change the very subject line he was bitching about.
Dr NoName wrote: >Hi all, > >I got another problem with postgres. This time it >refuses to use the indexes. Check this out: > If you would like help, first try posting queries and EXPLAIN ANALYZE dumps. Also you may have better luck with the Performance list (pgsql-perform@postgresql.org). Best Wishes, Chris Travers Metatron Technology Consulting
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Scott Marlowe wrote: > You might want to schedule analyzes to run every thirty minutes or every > hour. I doubt that is necessary or wise. Rerunning ANALYZE should only be necessary when the distribution of your data changes significantly -- e.g. after a bulk load or deletion of a lot of content. IMHO In most circumstances, running ANALYZE once a day is more than sufficient. -Neil
On Mon, 2005-08-08 at 15:30, Neil Conway wrote: > Scott Marlowe wrote: > > You might want to schedule analyzes to run every thirty minutes or every > > hour. > > I doubt that is necessary or wise. Rerunning ANALYZE should only be > necessary when the distribution of your data changes significantly -- > e.g. after a bulk load or deletion of a lot of content. IMHO In most > circumstances, running ANALYZE once a day is more than sufficient. I just let pg_autovacuum decide for me. Really is easier than doing it yourself.