-- create index tags1 on allwikitags(tagword) - after still 18 seconds
-- create index tags6 on allwikitags(tagword,instances desc, pagename) - after
now 32 seconds
-- drop index tags6
-- create index tags2 on allwikitags(instances) - after still 18 seconds
-- create index tags3 on allwikitags(soundex2)
-- create index tags4 on allwikitags(metaphone)
-- create index tags5 on allwikitags(metaphone2) - after 3 now 1 second
select pagename,tagword,instances from allwikitags
where tagword in
('journey','journeys','journeyes','journeyd','journeyed','journeyly','journeyy','journeyth','journeydom','journeying','journeyize','journeyion','journeyism','journeyized','journeyizes','journeyizing','journeyions','journeyists','journeyfulness','journeyise','journeyish','journeyist','journeyful','journeytion','journeyless','journeyable','journeyfull','journeyious','journeylike','journeyment','journeyness')
or soundex2 in ('J650')
or metaphone in ('jrny')
or metaphone2 in ('JRN')
group by pagename,tagword,instances
order by tagword,instances desc,pagename
Giving it indexes for each of the "or" elements got the 8.8 million row
query down to 1 second. So now, I just await for suggestions of how one would
debug this and know he needed to hang more indexes off the table?
Thanks,
Ozz
On Oct 5, 2010, at 3:02 PM, Ozz Nixon wrote:
> Good after everyone,
>
> We are experiencing some performance issues on a table with 7 fields,
> 8,800,000 rows. During some exercises, one thing I noticed is I need to
> change the configuration of the system to house pgsql_tmp on a host partition
> instead of the drive array... that will get me a little more speed... is this
> controlled via a .conf file or pgamin?
>
> Optimization questions:
>
> When is pgsql_tmp used? (Right now as I am creating indexes by hand, I
> see it grow for about 10 minutes):
>
> du -h /mnt/data/base/
> 5.1M /mnt/data/base/1
> 5.1M /mnt/data/base/11563
> 4.0G /mnt/data/base/11564
> 8.9M /mnt/data/base/16395
> 586M /mnt/data/base/pgsql_tmp
>
> During the create index - communications in general to the drive array
> is "consumed".
>
> Before I keep experimenting and making things worse, I will ask - what
> indexes should I have to make this query better - or how does on debug when
> they find a query is taking too long???
>
> STRUCTURE:
> quer.SQL.Add('create table '+DBTags+' (');
> quer.SQL.Add(' pagename '+SQL_TITLE+'(100) not null,');
> quer.SQL.Add(' tagword '+SQL_TITLE+'(15) not null,');
> quer.SQL.Add(' soundex2 '+SQL_TITLE+'(4) not null,');
> quer.SQL.Add(' metaphone '+SQL_TITLE+'(15) not null,');
> quer.SQL.Add(' metaphone2 '+SQL_TITLE+'(22) not null,');
> quer.SQL.Add(' carverphone '+SQL_TITLE+'(22) not null,');
> quer.SQL.Add(' instances '+SQL_INT32+' not null,');
> if SQL_NAME_PRIMARY_KEYS then quer.SQL.Add(' constraint '+DBTags+'_PK');
> quer.SQL.Add(' primary key(pagename, tagword, instances)');
>
>
> WAS 18 seconds with just the primary key, so I tried:
> create index tags1 on allwikitags(tagword) -- after still 18 seconds
>
> Then I tried:
> create index tags6 on allwikitags(tagword,instances desc, pagename) -- after
> now 32 seconds
>
>
> My Query:
>
> select pagename,tagword,instances from allwikitags
> where tagword in
> ('journey','journeys','journeyes','journeyd','journeyed','journeyly','journeyy','journeyth','journeydom','journeying','journeyize','journeyion','journeyism','journeyized','journeyizes','journeyizing','journeyions','journeyists','journeyfulness','journeyise','journeyish','journeyist','journeyful','journeytion','journeyless','journeyable','journeyfull','journeyious','journeylike','journeyment','journeyness')
> or soundex2 in ('J650')
> or metaphone in ('jrny')
> or metaphone2 in ('JRN')
> group by pagename,tagword,instances
> order by tagword,instances desc,pagename
>
> Thanks,
> Ozz
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