Re: understanding bitmap index benefit

On Thu, 19 May 2005, Tom Lane wrote:

> Oleg Bartunov <oleg(at)sai(dot)msu(dot)su> writes:
>> I tried to see io statistics, but it was weird in 8.0X and in 8.1dev I still
>> don't understand it :)
>
> We aren't yet updating the io statistics for bitmap scans properly.
> There was a thread about this but it petered out without any resolution
> about what we should do ...

what's 'Bitmap Heap Scan' ?

Bitmap Heap Scan on titles (cost=5.32..1349.79 rows=378 width=41) (actual time=76.601..111.207 rows=4153 loops=1)
Filter: (fts_index @@ '\'list\''::tsquery)
-> Bitmap Index Scan on fts_idx (cost=0.00..5.32 rows=378 width=0) (actual time=74.943..74.943 rows=4154 loops=1)
Index Cond: (fts_index @@ '\'list\''::tsquery)

>
> regards, tom lane
>

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83