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Optimizing query

P: n/a
Hello!

I have some trouble getting good results from my query.

here is structure

stat_views
id | integer
id_zone | integer
created | timestamp
I have btree index on created and also id and there is 1633832 records in
that table

First of all I have to manualy set seq_scan to OFF because I always get
seq_scan. When i set it to off my explain show:

explain SELECT count(*) as views FROM stat_views WHERE id = 12;
QUERY PLAN
----------------------------------------------------------------------------------------------------
Aggregate (cost=122734.86..122734.86 rows=1 width=0)
-> Index Scan using stat_views_id_idx on stat_views (cost=0.00..122632.60 rows=40904 width=0)
Index Cond: (id = 12)

But what I need is to count views for some day, so I use

explain SELECT count(*) as views FROM stat_views WHERE date_part('day', created) = 18;

QUERY PLAN
------------------------------------------------------------------------------------
Aggregate (cost=100101618.08..100101618.08 rows=1 width=0)
-> Seq Scan on stat_views (cost=100000000.00..100101565.62 rows=20984 width=0)
Filter: (date_part('day'::text, created) = 18::double precision)
How can I make this to use index and speed the query. Now it takes about 12
seconds.

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Best regards,
Uros mailto:ur**@sir-mag.com
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Nov 12 '05 #1
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P: n/a
Do something like:

CREATE OR REPLACE FUNCTION my_date_part( timestamp) RETURNS DOUBLE precision AS '
DECLARE
mydate ALIAS FOR $1;
BEGIN
return date_part( ''day'', mydate );
END;' LANGUAGE 'plpgsql' IMMUTABLE;

create index idx_tmp on stat_views( my_date_part( created ) );

or add an extra date_part column to your table which pre-calculates date_part('day', created) and put an index on this.

Cheers
Matthew
--

----- Original Message -----
From: Uros
To: pg***********@postgresql.org
Sent: Wednesday, November 19, 2003 10:41 AM
Subject: [GENERAL] Optimizing query
Hello!

I have some trouble getting good results from my query.

here is structure

stat_views
id | integer
id_zone | integer
created | timestamp
I have btree index on created and also id and there is 1633832 records in
that table

First of all I have to manualy set seq_scan to OFF because I always get
seq_scan. When i set it to off my explain show:

explain SELECT count(*) as views FROM stat_views WHERE id = 12;
QUERY PLAN
----------------------------------------------------------------------------------------------------
Aggregate (cost=122734.86..122734.86 rows=1 width=0)
-> Index Scan using stat_views_id_idx on stat_views (cost=0.00..122632.60 rows=40904 width=0)
Index Cond: (id = 12)

But what I need is to count views for some day, so I use

explain SELECT count(*) as views FROM stat_views WHERE date_part('day', created) = 18;

QUERY PLAN
------------------------------------------------------------------------------------
Aggregate (cost=100101618.08..100101618.08 rows=1 width=0)
-> Seq Scan on stat_views (cost=100000000.00..100101565.62 rows=20984 width=0)
Filter: (date_part('day'::text, created) = 18::double precision)
How can I make this to use index and speed the query. Now it takes about 12
seconds.

--
Best regards,
Uros mailto:ur**@sir-mag.com
---------------------------(end of broadcast)---------------------------
TIP 1: subscribe and unsubscribe commands go to ma*******@postgresql.org

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Nov 12 '05 #2

P: n/a
Uros writes:
explain SELECT count(*) as views FROM stat_views WHERE date_part('day', created) = 18;

QUERY PLAN
------------------------------------------------------------------------------------
Aggregate (cost=100101618.08..100101618.08 rows=1 width=0)
-> Seq Scan on stat_views (cost=100000000.00..100101565.62 rows=20984 width=0)
Filter: (date_part('day'::text, created) = 18::double precision)


Create an index on date_part('day', created). In 7.3 and earlier you need
to create a wrapper function and index that, in 7.4 you can index
arbitrarz expressions directly. The documentation contains more
information about that.

--
Peter Eisentraut pe*****@gmx.net
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Nov 12 '05 #3

P: n/a
Uros wrote:
Hello!

I have some trouble getting good results from my query.

here is structure

stat_views
id | integer
id_zone | integer
created | timestamp
I have btree index on created and also id and there is 1633832 records in
that table

First of all I have to manualy set seq_scan to OFF because I always get
seq_scan. When i set it to off my explain show:

explain SELECT count(*) as views FROM stat_views WHERE id = 12;
QUERY PLAN
----------------------------------------------------------------------------------------------------
Aggregate (cost=122734.86..122734.86 rows=1 width=0)
-> Index Scan using stat_views_id_idx on stat_views (cost=0.00..122632.60 rows=40904 width=0)
Index Cond: (id = 12)

But what I need is to count views for some day, so I use

explain SELECT count(*) as views FROM stat_views WHERE date_part('day', created) = 18;

QUERY PLAN
------------------------------------------------------------------------------------
Aggregate (cost=100101618.08..100101618.08 rows=1 width=0)
-> Seq Scan on stat_views (cost=100000000.00..100101565.62 rows=20984 width=0)
Filter: (date_part('day'::text, created) = 18::double precision)
How can I make this to use index and speed the query. Now it takes about 12
seconds.


Can you post explain analyze for the same?

Shridhar

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Nov 12 '05 #4

P: n/a
Hello Shridhar,

I use Matthew's solution and it works. Query takes only half a second. I
didn't know that i can index function to.

Thanks

Uros

Wednesday, November 19, 2003, 1:23:26 PM, you wrote:

SD> Uros wrote:
Hello!

I have some trouble getting good results from my query.

here is structure

stat_views
id | integer
id_zone | integer
created | timestamp
I have btree index on created and also id and there is 1633832 records in
that table

First of all I have to manualy set seq_scan to OFF because I always get
seq_scan. When i set it to off my explain show:

explain SELECT count(*) as views FROM stat_views WHERE id = 12;
QUERY PLAN
----------------------------------------------------------------------------------------------------
Aggregate (cost=122734.86..122734.86 rows=1 width=0)
-> Index Scan using stat_views_id_idx on stat_views
(cost=0.00..122632.60 rows=40904 width=0)
Index Cond: (id = 12)

But what I need is to count views for some day, so I use

explain SELECT count(*) as views FROM stat_views WHERE date_part('day', created) = 18;

QUERY PLAN
------------------------------------------------------------------------------------
Aggregate (cost=100101618.08..100101618.08 rows=1 width=0)
-> Seq Scan on stat_views (cost=100000000.00..100101565.62 rows=20984 width=0)
Filter: (date_part('day'::text, created) = 18::double precision)
How can I make this to use index and speed the query. Now it takes about 12
seconds.


SD> Can you post explain analyze for the same?

SD> Shridhar



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Nov 12 '05 #5

P: n/a
Greetings all,

Yesterday I upgraded from 7.3 to 7.4 now psql doesn't work! I get the
following error.

psql: relocation error: psql: undefined symbol: get_progname

Any ideas out there?

Rob

-----Original Message-----
From: pg*****************@postgresql.org
[mailto:pg*****************@postgresql.org] On Behalf Of Shridhar Daithankar
Sent: Wednesday, November 19, 2003 6:23 AM
To: Uros
Cc: pg***********@postgresql.org
Subject: Re: [GENERAL] Optimizing query

Uros wrote:
Hello!

I have some trouble getting good results from my query.

here is structure

stat_views
id | integer
id_zone | integer
created | timestamp
I have btree index on created and also id and there is 1633832 records in
that table

First of all I have to manualy set seq_scan to OFF because I always get
seq_scan. When i set it to off my explain show:

explain SELECT count(*) as views FROM stat_views WHERE id = 12;
QUERY PLAN
----------------------------------------------------------------------------
------------------------ Aggregate (cost=122734.86..122734.86 rows=1 width=0)
-> Index Scan using stat_views_id_idx on stat_views (cost=0.00..122632.60 rows=40904 width=0) Index Cond: (id = 12)

But what I need is to count views for some day, so I use

explain SELECT count(*) as views FROM stat_views WHERE date_part('day', created) = 18;
QUERY PLAN
----------------------------------------------------------------------------
-------- Aggregate (cost=100101618.08..100101618.08 rows=1 width=0)
-> Seq Scan on stat_views (cost=100000000.00..100101565.62 rows=20984 width=0) Filter: (date_part('day'::text, created) = 18::double precision)
How can I make this to use index and speed the query. Now it takes about 12 seconds.


Can you post explain analyze for the same?

Shridhar

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Nov 12 '05 #6

P: n/a
Rob Sell wrote:
Greetings all,

Yesterday I upgraded from 7.3 to 7.4 now psql doesn't work! I get the
following error.

psql: relocation error: psql: undefined symbol: get_progname

Any ideas out there?


You have an old copy of the library or binaries around somewhere.

--
Bruce Momjian | http://candle.pha.pa.us
pg***@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

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Nov 12 '05 #7

This discussion thread is closed

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