Обсуждение: Help with Query Tuning

Dear all,

I am facing a problem while  creating the index to make the below query run faster. My table  size is near about 1065 MB and 428467 rows.

explain analyze select  count(*)  from page_content where publishing_date like '%2010%' and content_language='en'  and content is not null and isprocessable = 1 and (content like '%Militant%'
OR content like '%jihad%' OR  content like '%Mujahid%'  OR
 content like '%fedayeen%' OR content like '%insurgent%'  OR content like '%terrorist%' OR
  content like '%cadre%'  OR content like '%civilians%' OR content like '%police%' OR content like '%defence%' OR content like '%cops%' OR content like '%crpf%' OR content like '%dsf%' OR content like '%ssb%') AND (content like '%kill%' or content like '%injure%');

Output:

 Aggregate  (cost=107557.78..107557.79 rows=1 width=0) (actual time=18564.631..18564.631 rows=1 loops=1)
   ->  Seq Scan on page_content  (cost=0.00..107466.82 rows=36381 width=0) (actual time=0.146..18529.371 rows=59918 loops=1)
         Filter: ((content IS NOT NULL) AND (publishing_date ~~ '%2010%'::text) AND (content_language = 'en'::bpchar) AND (isprocessable = 1) AND (((content)
::text ~~ '%kill%'::text) OR ((content)::text ~~ '%injure%'::text)) AND (((content)::text ~~ '%Militant%'::text) OR ((content)::text ~~ '%jihad%'::text) OR (
(content)::text ~~ '%Mujahid%'::text) OR ((content)::text ~~ '%fedayeen%'::text) OR ((content)::text ~~ '%insurgent%'::text) OR ((content)::text ~~ '%terrori
st%'::text) OR ((content)::text ~~ '%cadre%'::text) OR ((content)::text ~~ '%civilians%'::text) OR ((content)::text ~~ '%police%'::text) OR ((content)::text
~~ '%defence%'::text) OR ((content)::text ~~ '%cops%'::text) OR ((content)::text ~~ '%crpf%'::text) OR ((content)::text ~~ '%dsf%'::text) OR ((content)::text
 ~~ '%ssb%'::text)))
 Total runtime: 18564.673 ms


Index on that Table :

CREATE INDEX idx_page_id
  ON page_content
  USING btree
  (crawled_page_id);

Index I create :
CREATE INDEX idx_page_id_content
  ON page_content
  USING btree
  (crawled_page_id,content_language,publishing_date,isprocessable);

Index that fail to create:

CREATE INDEX idx_page_id_content1
  ON page_content
  USING btree
  (crawled_page_id,content);

Error :-ERROR:  index row requires 13240 bytes, maximum size is 8191
********** Error **********

ERROR: index row requires 13240 bytes, maximum size is 8191
SQL state: 54000

How to resolve this error
Please give any suggestion to tune the query.

Thanks & best Regards,

Adarsh Sharma

On Wed, Mar 16, 2011 at 02:43:38PM +0530, Adarsh Sharma wrote:
> Dear all,
>
> I am facing a problem while  creating the index to make the below query run
> faster. My table  size is near about 1065 MB and 428467 rows.
>
> explain analyze select  count(*)  from page_content where publishing_date
> like '%2010%' and content_language='en'  and content is not null and
> isprocessable = 1 and (content like '%Militant%'
> OR content like '%jihad%' OR  content like '%Mujahid%'  OR
> content like '%fedayeen%' OR content like '%insurgent%'  OR content like
> '%terrorist%' OR
>  content like '%cadre%'  OR content like '%civilians%' OR content like
> '%police%' OR content like '%defence%' OR content like '%cops%' OR content
> like '%crpf%' OR content like '%dsf%' OR content like '%ssb%') AND (content
> like '%kill%' or content like '%injure%');
>
> *Output:
>
> * Aggregate  (cost=107557.78..107557.79 rows=1 width=0) (actual
> time=18564.631..18564.631 rows=1 loops=1)
>   ->  Seq Scan on page_content  (cost=0.00..107466.82 rows=36381 width=0)
> (actual time=0.146..18529.371 rows=59918 loops=1)
>         Filter: ((content IS NOT NULL) AND (publishing_date ~~
> '%2010%'::text) AND (content_language = 'en'::bpchar) AND (isprocessable =
> 1) AND (((content)
> ::text ~~ '%kill%'::text) OR ((content)::text ~~ '%injure%'::text)) AND
> (((content)::text ~~ '%Militant%'::text) OR ((content)::text ~~
> '%jihad%'::text) OR (
> (content)::text ~~ '%Mujahid%'::text) OR ((content)::text ~~
> '%fedayeen%'::text) OR ((content)::text ~~ '%insurgent%'::text) OR
> ((content)::text ~~ '%terrori
> st%'::text) OR ((content)::text ~~ '%cadre%'::text) OR ((content)::text ~~
> '%civilians%'::text) OR ((content)::text ~~ '%police%'::text) OR
> ((content)::text
> ~~ '%defence%'::text) OR ((content)::text ~~ '%cops%'::text) OR
> ((content)::text ~~ '%crpf%'::text) OR ((content)::text ~~ '%dsf%'::text)
> OR ((content)::text
> ~~ '%ssb%'::text)))
> Total runtime: 18564.673 ms
>
>
> *Index on that Table :
>
> *CREATE INDEX idx_page_id
>  ON page_content
>  USING btree
>  (crawled_page_id);
>
> *Index I create :*
> CREATE INDEX idx_page_id_content
>  ON page_content
>  USING btree
>  (crawled_page_id,content_language,publishing_date,isprocessable);
>
> *Index that fail to create:
>
> *CREATE INDEX idx_page_id_content1
>  ON page_content
>  USING btree
>  (crawled_page_id,content);
>
> Error :-ERROR:  index row requires 13240 bytes, maximum size is 8191
> ********** Error **********
>
> ERROR: index row requires 13240 bytes, maximum size is 8191
> SQL state: 54000
>
> How to resolve this error
> Please give any suggestion to tune the query.
>
> Thanks & best Regards,
>
> Adarsh Sharma
>

You should probably be looking at using full-text indexing:

http://www.postgresql.org/docs/9.0/static/textsearch.html

or limit the size of content for the index.

Cheers,
Ken

On 03/16/2011 05:13 AM, Adarsh Sharma wrote:
> Dear all,
>
> I am facing a problem while creating the index to make the below query run faster. My table size is near about 1065
MBand 428467 rows. 
>
> explain analyze select count(*) from page_content where publishing_date like '%2010%' and content_language='en' and
contentis not 
> null and isprocessable = 1 and (content like '%Militant%'
> OR content like '%jihad%' OR content like '%Mujahid%' OR
> content like '%fedayeen%' OR content like '%insurgent%' OR content like '%terrorist%' OR
> content like '%cadre%' OR content like '%civilians%' OR content like '%police%' OR content like '%defence%' OR
contentlike '%cops%' 
> OR content like '%crpf%' OR content like '%dsf%' OR content like '%ssb%') AND (content like '%kill%' or content like
'%injure%');
>
> *Output:
>
> * Aggregate (cost=107557.78..107557.79 rows=1 width=0) (actual time=18564.631..18564.631 rows=1 loops=1)
> -> Seq Scan on page_content (cost=0.00..107466.82 rows=36381 width=0) (actual time=0.146..18529.371 rows=59918
loops=1)
> Filter: ((content IS NOT NULL) AND (publishing_date ~~ '%2010%'::text) AND (content_language = 'en'::bpchar) AND
(isprocessable= 1) 
> AND (((content)
> ::text ~~ '%kill%'::text) OR ((content)::text ~~ '%injure%'::text)) AND (((content)::text ~~ '%Militant%'::text) OR
((content)::text
> ~~ '%jihad%'::text) OR (
> (content)::text ~~ '%Mujahid%'::text) OR ((content)::text ~~ '%fedayeen%'::text) OR ((content)::text ~~
'%insurgent%'::text)OR 
> ((content)::text ~~ '%terrori
> st%'::text) OR ((content)::text ~~ '%cadre%'::text) OR ((content)::text ~~ '%civilians%'::text) OR ((content)::text
~~
> '%police%'::text) OR ((content)::text
> ~~ '%defence%'::text) OR ((content)::text ~~ '%cops%'::text) OR ((content)::text ~~ '%crpf%'::text) OR
((content)::text~~ 
> '%dsf%'::text) OR ((content)::text
> ~~ '%ssb%'::text)))
> Total runtime: 18564.673 ms
>

You should read the documentation regarding indices and pattern matching as well as fts.

http://www.postgresql.org/docs/8.3/static/indexes-types.html

The optimizer can also use a B-tree index for queries involving the pattern matching operators LIKE and ~ if the
patternis a  
constant and is anchored to the beginning of the string — for example, col LIKE 'foo%' or col ~ '^foo', but not col
LIKE'%bar'.  
However, if your server does not use the C locale you will need to create the index with a special operator class to
support 
indexing of pattern-matching queries. See Section 11.9 below. It is also possible to use B-tree indexes for ILIKE and
~*,but only  
if the pattern starts with non-alphabetic characters, i.e. characters that are not affected by upper/lower case
conversion.

I believe that your query as written using '%pattern%' will always be forced to use sequential scans.

Thanks Marshall, would I need to change the data type  of content column to tsvector and create a Gist Index on it.

Best Regards,
Adarsh


Kenneth Marshall wrote:

On Wed, Mar 16, 2011 at 02:43:38PM +0530, Adarsh Sharma wrote: 

Dear all,

I am facing a problem while  creating the index to make the below query run 
faster. My table  size is near about 1065 MB and 428467 rows.

explain analyze select  count(*)  from page_content where publishing_date 
like '%2010%' and content_language='en'  and content is not null and 
isprocessable = 1 and (content like '%Militant%'
OR content like '%jihad%' OR  content like '%Mujahid%'  OR
content like '%fedayeen%' OR content like '%insurgent%'  OR content like 
'%terrorist%' ORcontent like '%cadre%'  OR content like '%civilians%' OR content like 
'%police%' OR content like '%defence%' OR content like '%cops%' OR content 
like '%crpf%' OR content like '%dsf%' OR content like '%ssb%') AND (content 
like '%kill%' or content like '%injure%');

*Output:

* Aggregate  (cost=107557.78..107557.79 rows=1 width=0) (actual 
time=18564.631..18564.631 rows=1 loops=1) ->  Seq Scan on page_content  (cost=0.00..107466.82 rows=36381 width=0) 
(actual time=0.146..18529.371 rows=59918 loops=1)       Filter: ((content IS NOT NULL) AND (publishing_date ~~ 
'%2010%'::text) AND (content_language = 'en'::bpchar) AND (isprocessable = 
1) AND (((content)
::text ~~ '%kill%'::text) OR ((content)::text ~~ '%injure%'::text)) AND 
(((content)::text ~~ '%Militant%'::text) OR ((content)::text ~~ 
'%jihad%'::text) OR (
(content)::text ~~ '%Mujahid%'::text) OR ((content)::text ~~ 
'%fedayeen%'::text) OR ((content)::text ~~ '%insurgent%'::text) OR 
((content)::text ~~ '%terrori
st%'::text) OR ((content)::text ~~ '%cadre%'::text) OR ((content)::text ~~ 
'%civilians%'::text) OR ((content)::text ~~ '%police%'::text) OR 
((content)::text
~~ '%defence%'::text) OR ((content)::text ~~ '%cops%'::text) OR 
((content)::text ~~ '%crpf%'::text) OR ((content)::text ~~ '%dsf%'::text) 
OR ((content)::text
~~ '%ssb%'::text)))
Total runtime: 18564.673 ms


*Index on that Table :

*CREATE INDEX idx_page_idON page_contentUSING btree(crawled_page_id);

*Index I create :*
CREATE INDEX idx_page_id_contentON page_contentUSING btree(crawled_page_id,content_language,publishing_date,isprocessable);

*Index that fail to create:

*CREATE INDEX idx_page_id_content1ON page_contentUSING btree(crawled_page_id,content);

Error :-ERROR:  index row requires 13240 bytes, maximum size is 8191
********** Error **********

ERROR: index row requires 13240 bytes, maximum size is 8191
SQL state: 54000

How to resolve this error
Please give any suggestion to tune the query.

Thanks & best Regards,

Adarsh Sharma
   

You should probably be looking at using full-text indexing:

http://www.postgresql.org/docs/9.0/static/textsearch.html

or limit the size of content for the index.

Cheers,
Ken 

Thanks, I understand it know :-

But My one doubt which isn't clear  :

Original Query :-

select  count(*)  from page_content where (content like '%Militant%'
OR content like '%jihad%' OR  content like '%Mujahid%'  OR
 content like '%fedayeen%' OR content like '%insurgent%'  OR content like '%terrORist%' OR
  content like '%cadre%'  OR content like '%civilians%' OR content like '%police%' OR content like '%defence%' OR content like '%cops%' OR content like '%crpf%' OR content like '%dsf%' OR content like '%ssb%') AND (content like '%kill%' OR content like '%injure%');

Output :-
 count
-------
 57061
(1 row)

Time: 19726.555 ms

I need to tune it , use full-text searching as :

Modified Query :-

SELECT count(*)  from page_content
WHERE publishing_date like '%2010%' and content_language='en' and content is not null and isprocessable = 1 and to_tsvectOR('english',content) @@ to_tsquery('english','Mujahid' || 'jihad' || 'Militant' || 'fedayeen' || 'insurgent' || 'terrORist' || 'cadre' || 'civilians' || 'police' || 'defence' || 'cops' || 'crpf' || 'dsf' || 'ssb');

Output :-
 count
-------
     0
(1 row)

Time: 194685.125 ms

I try, SELECT count(*)  from page_content
WHERE publishing_date like '%2010%' and content_language='en' and content is not null and isprocessable = 1 and to_tsvectOR('english',content) @@ to_tsquery('english','%Mujahid%' || '%jihad%' || '%Militant%' || '%fedayeen%' || '%insurgent%' || '%terrORist%' || '%cadre%' || '%civilians%' || '%police%' || '%defence%' || '%cops%' || '%crpf%' || '%dsf%' || '%ssb%');

 count
-------
     0
(1 row)

Time: 194722.468 ms

I know I have to create index but index is the next step, first you have to get the correct result .

CREATE INDEX pgweb_idx ON page_content USING gin(to_tsvector('english', content));


Please guide me where I am going wrong.


Thanks & best Regards,

Adarsh Sharma
Kenneth Marshall wrote:

On Wed, Mar 16, 2011 at 02:43:38PM +0530, Adarsh Sharma wrote: 

Dear all,

I am facing a problem while  creating the index to make the below query run 
faster. My table  size is near about 1065 MB and 428467 rows.

explain analyze select  count(*)  from page_content where publishing_date 
like '%2010%' and content_language='en'  and content is not null and 
isprocessable = 1 and (content like '%Militant%'
OR content like '%jihad%' OR  content like '%Mujahid%'  OR
content like '%fedayeen%' OR content like '%insurgent%'  OR content like 
'%terrorist%' ORcontent like '%cadre%'  OR content like '%civilians%' OR content like 
'%police%' OR content like '%defence%' OR content like '%cops%' OR content 
like '%crpf%' OR content like '%dsf%' OR content like '%ssb%') AND (content 
like '%kill%' or content like '%injure%');

*Output:

* Aggregate  (cost=107557.78..107557.79 rows=1 width=0) (actual 
time=18564.631..18564.631 rows=1 loops=1) ->  Seq Scan on page_content  (cost=0.00..107466.82 rows=36381 width=0) 
(actual time=0.146..18529.371 rows=59918 loops=1)       Filter: ((content IS NOT NULL) AND (publishing_date ~~ 
'%2010%'::text) AND (content_language = 'en'::bpchar) AND (isprocessable = 
1) AND (((content)
::text ~~ '%kill%'::text) OR ((content)::text ~~ '%injure%'::text)) AND 
(((content)::text ~~ '%Militant%'::text) OR ((content)::text ~~ 
'%jihad%'::text) OR (
(content)::text ~~ '%Mujahid%'::text) OR ((content)::text ~~ 
'%fedayeen%'::text) OR ((content)::text ~~ '%insurgent%'::text) OR 
((content)::text ~~ '%terrori
st%'::text) OR ((content)::text ~~ '%cadre%'::text) OR ((content)::text ~~ 
'%civilians%'::text) OR ((content)::text ~~ '%police%'::text) OR 
((content)::text
~~ '%defence%'::text) OR ((content)::text ~~ '%cops%'::text) OR 
((content)::text ~~ '%crpf%'::text) OR ((content)::text ~~ '%dsf%'::text) 
OR ((content)::text
~~ '%ssb%'::text)))
Total runtime: 18564.673 ms


*Index on that Table :

*CREATE INDEX idx_page_idON page_contentUSING btree(crawled_page_id);

*Index I create :*
CREATE INDEX idx_page_id_contentON page_contentUSING btree(crawled_page_id,content_language,publishing_date,isprocessable);

*Index that fail to create:

*CREATE INDEX idx_page_id_content1ON page_contentUSING btree(crawled_page_id,content);

Error :-ERROR:  index row requires 13240 bytes, maximum size is 8191
********** Error **********

ERROR: index row requires 13240 bytes, maximum size is 8191
SQL state: 54000

How to resolve this error
Please give any suggestion to tune the query.

Thanks & best Regards,

Adarsh Sharma
   

You should probably be looking at using full-text indexing:

http://www.postgresql.org/docs/9.0/static/textsearch.html

or limit the size of content for the index.

Cheers,
Ken 

> *Modified Query :-
>
> *SELECT count(*)  from page_content
> WHERE publishing_date like '%2010%' and content_language='en' and
> content is not null and isprocessable = 1 and
> to_tsvectOR('english',content) @@ to_tsquery('english','Mujahid' ||
> 'jihad' || 'Militant' || 'fedayeen' || 'insurgent' || 'terrORist' ||
> 'cadre' || 'civilians' || 'police' || 'defence' || 'cops' || 'crpf' ||
> 'dsf' || 'ssb');

I guess there should be spaces between the words. This way it's just one
very long word 'MujahidjihadMilitantfedayeen....' and I doubt that's what
you're looking for.

regards
Tomas

Thanks , it works now .. :-)

Here is the output :

pdc_uima=# SELECT count(*)  from page_content WHERE publishing_date like '%2010%' and
pdc_uima-# content_language='en' and content is not null and isprocessable = 1 and
pdc_uima-# to_tsvector('english',content) @@ to_tsquery('english','Mujahid' || ' | '
pdc_uima(# || 'jihad' || ' | ' || 'Militant' || ' | ' || 'fedayeen' || ' | '
pdc_uima(# || 'insurgent' || ' | ' || 'terrORist' || ' | ' || 'cadre' || ' | '
pdc_uima(# || 'civilians' || ' | ' || 'police' || ' | ' || 'cops' || 'crpf' || ' | '
pdc_uima(# || 'defence' || ' | ' || 'dsf' || ' | ' || 'ssb' );

 count 
--------
 137193
(1 row)

Time: 195441.894 ms


But my original query is to use AND also i.e

select  count(*)  from page_content where publishing_date like '%2010%' and content_language='en'  and content is not null and isprocessable = 1 and (content like '%Militant%'
OR content like '%jihad%' OR  content like '%Mujahid%'  OR
 content like '%fedayeen%' OR content like '%insurgent%'  OR content like '%terrORist%' OR
  content like '%cadre%'  OR content like '%civilians%' OR content like '%police%' OR content like '%defence%' OR content like '%cops%' OR content like '%crpf%' OR content like '%dsf%' OR content like '%ssb%') AND (content like '%kill%' OR content like '%injure%');

 count
-------
 57061
(1 row)

Time: 19423.087 ms


Now I have to add AND condition (  AND (content like '%kill%' OR content like '%injure%')  )  also.


Thanks & Regards,
Adarsh Sharma



tv@fuzzy.cz wrote:

tv@fuzzy.cz wrote:   

Yes , I think we caught the problem but it results in the below error :

SELECT count(*)  from page_content
WHERE publishing_date like '%2010%' and content_language='en' and
content is not null and isprocessable = 1 and
to_tsvector('english',content) @@ to_tsquery('english','Mujahid ' ||
'jihad ' || 'Militant ' || 'fedayeen ' || 'insurgent ' || 'terrORist '
|| 'cadre ' || 'civilians ' || 'police ' || 'defence ' || 'cops ' ||
'crpf ' || 'dsf ' || 'ssb');

ERROR:  syntax error in tsquery: "Mujahid jihad Militant fedayeen
insurgent terrORist cadre civilians police defence cops crpf dsf ssb"
       

The text passed to to_tsquery has to be a proper query, i.e. single
tokens
separated by boolean operators. In your case, you should put there '|'
(which means OR) to get something like this
 'Mujahid | jihad | Militant | ...'

or you can use plainto_tsquery() as that accepts simple text, but it
puts
'&' (AND) between the tokens and I guess that's not what you want.

Tomas

     

What to do to make it satisfies the OR condition to match any of the
to_tsquery values as we got it right through like '%Mujahid' or .....
or ....   

You can't force the plainto_tsquery to somehow use the OR instead of AND.
You need to modify the piece of code that produces the search text to put
there '|' characters. So do something like this

SELECT count(*)  from page_content WHERE publishing_date like '%2010%' and
content_language='en' and content is not null and isprocessable = 1 and
to_tsvector('english',content) @@ to_tsquery('english','Mujahid' || ' | '
|| 'jihad' || ' | ' || 'Militant' || ' | ' || 'fedayeen);

Not sure where does this text come from, but you can do this in a higher
level language, e.g. in PHP. Something like this

$words = implode(' | ', explode(' ',$text));

and then pass the $words into the query. Or something like that.

Tomas
 

On 03/18/2011 12:17 AM, Adarsh Sharma wrote:
> Thanks , it works now ..:-)
>
> Here is the output :
>
> pdc_uima=# SELECT count(*)  from page_content WHERE publishing_date like '%2010%' and
> pdc_uima-# content_language='en' and content is not null and isprocessable = 1 and
> pdc_uima-# to_tsvector('english',content) @@ to_tsquery('english','Mujahid' || ' | '
> pdc_uima(# || 'jihad' || ' | ' || 'Militant' || ' | ' || 'fedayeen' || ' | '
> pdc_uima(# || 'insurgent' || ' | ' || 'terrORist' || ' | ' || 'cadre' || ' | '
> pdc_uima(# || 'civilians' || ' | ' || 'police' || ' | ' || 'cops' || 'crpf' || ' | '
> pdc_uima(# || 'defence' || ' | ' || 'dsf' || ' | ' || 'ssb' );
>
>   count
> --------
>   137193
> (1 row)
>
> Time: 195441.894 ms

what is the type/content for column publishing_date?
based on what you show above, I assume it's text? -- if so, whats the format of the date string?

> Thanks , it works now .. :-)
>
> Here is the output :
>
> pdc_uima=# SELECT count(*)  from page_content WHERE publishing_date like
> '%2010%' and
> pdc_uima-# content_language='en' and content is not null and
> isprocessable = 1 and
> pdc_uima-# to_tsvector('english',content) @@
> to_tsquery('english','Mujahid' || ' | '
> pdc_uima(# || 'jihad' || ' | ' || 'Militant' || ' | ' || 'fedayeen' || ' |
> '
> pdc_uima(# || 'insurgent' || ' | ' || 'terrORist' || ' | ' || 'cadre' ||
> ' | '
> pdc_uima(# || 'civilians' || ' | ' || 'police' || ' | ' || 'cops' ||
> 'crpf' || ' | '
> pdc_uima(# || 'defence' || ' | ' || 'dsf' || ' | ' || 'ssb' );
>
>  count
> --------
>  137193
> (1 row)
>
> Time: 195441.894 ms
>
>
> But my original query is to use AND also i.e

Hi, just replace "AND" and "OR" (used with LIKE operator) for "&" and "|"
(used with to_tsquery).

So this

(content like '%Militant%' OR content like '%jihad%') AND (content like
'%kill%' OR content like '%injure%')

becomes

to_tsvector('english',content) @@ to_tsquery('english', '(Militant |
jihad) & (kill | injure)')

BTW it seems you somehow believe you'll get exactly the same result from
those two queries (LIKE vs. tsearch) - that's false expectation. I believe
the fulltext query is much better and more appropriate in this case, just
don't expect the same results.

regards
Tomas