Обсуждение: Beta3 much slower than Beta2

Hi!



I just tried to use the new Beta 3 of PostGRE SQL 8.0. However, I found that
the Beta 3 is much slower than the B2.



To the setup: I use the Win32 version of PGRE SQL8. The table that I am
working with has about 1.1M records in it and is indexed on several columns.
By searching the indexed columns the DB used to be very fast. The data
retrieval used to be more or less instantaneous. In Beta 3 it takes about 4
seconds to retrieve the same amount of data. E.g. I searched for "EAG",
which returns about 50 records. In B2 the retrieval time was less than 1s,
in B3 it's about 3-4 seconds.



Thx,

Enrico

Enrico Riedel wrote:
> To the setup: I use the Win32 version of PGRE SQL8. The table that I am
> working with has about 1.1M records in it and is indexed on several columns.
> By searching the indexed columns the DB used to be very fast. The data
> retrieval used to be more or less instantaneous. In Beta 3 it takes about 4
> seconds to retrieve the same amount of data. E.g. I searched for "EAG",
> which returns about 50 records. In B2 the retrieval time was less than 1s,
> in B3 it's about 3-4 seconds.

This is likely not a bug in beta3 as such; what has probably happened is
that the query planner is choosing a different query plan in beta3 than
was chosen in beta2. Without more information, it is difficult to say
exactly why a different plan is being chosen. Have you run ANALYZE
recently? If so, can you provide the schemas of the relevant tables, the
query that has changed in performance, and the EXPLAIN ANALYZE output
for that query against beta3?

-Neil

I switched "in place" from beta2 to beta3 on windows some weeks ago
(selfcompiled), no notable speed difference.

Did you the usual "analyze" ritual???
Are the indexes used? Did you compare the "explain" outputs?

Are the indexes really present?

Harald

>I switched "in place" from beta2 to beta3 on windows some weeks ago
>(selfcompiled), no notable speed difference.

There may be a different issue here as well. The pginstaller version is
"beta3deva1", which is *not* beta3. It is a post-beta3 snapshot from oct
20th. If something has changed there, that could be the reason.

That said, I haven't noticed these symptoms myelf, so I'd check the
other suggestions first.

//Magnus