Re: Urgent need of (paid) PostgreSQL support in New

Hello Doug:

Professional help might cost more than a powerful server.

Ezra Taylor



Doug Fields wrote:

> Hello,
>
> Thanks for the response. I believe I have these bases covered:
>
>> - You run vacumm analyze often. This is one of the most important
>> procedures and needs to be frequent. If you fail to do so, your database
>> will most likely slow down.
>
>
> I ANALYZE every 8 hours at most, whenever new data is finished being
> imported.
>
> I VACUUM irregularly, as my tables mostly grow in size and don't get
> trimmed regularly. Hence, I VACUUM whenever there is any major shrinkage.
>
>> - Are you REALLY sure that indices are being used? For that, use
>> EXPLAIN <query> to see that. Note that I had real trouble until I
>> noticed
>> that PostgreSQL still does not recognize type casts, so for instance,
>> if you got a bigint key, a select * from table where key = 12312 will
>> not
>> use indices. A "select * from table where key = 12312::int8" will be
>> necessary. This is valid for EVERY "non-standard" type.
>
>
> I'm certain that the indices are being used. I've EXPLAINed to death
> over the last year. I've even made my queries do things like "SET
> ENABLE_NESTLOOP=OFF;SET ENABLE_SEQSCAN=OFF;query...;RESET..." in order
> to force usage of the indices for some of the queries.
>
> We don't use any non-standard types (although we may move to a
> BIGSERIAL one day) except for BOOLEAN.
>
>> - If your "data importing" is done via inserts, make sure that the
>> batch uses transactions for each (at least or so) 200 inserts. If you
>> don't, each insert will be a transaction, what will slow down you.
>
>
> Indeed. At first, I did:
>
> BEGIN WORK;INSERT...; INSERT...;COMMIT; and so forth to ensure they
> were in a transaction.
>
> Later, I imported the whole thing into a temporary table, then INSERT
> INTO real_table SELECT * FROM temp_table to make it even faster (or so
> I thought).
>
> The biggest slowdown seems to come when there are queries of the form:
>
> 1) INSERT INTO tableA SELECT * FROM temp_table
> executing simultaneously with queries of the form
> 2) INSERT INTO tableB SELECT column FROM tableA WHERE various clauses
>
> Of course, #1 happens after a bunch of inserts into temp_table, but
> those go very fast.
>
> Either of those queries, in themselves, go slowly (for #2) or are
> frequent (for #1).
>
> We have 8GB RAM. I've allocated about 700 megs to shared memory. The
> rest is buffer cached by the O/S. I can't afford a 32 gig server as 2
> gig RAM modules are exorbitantly expensive. The database won't fit
> into RAM anyway.
>
> At this point, after working with variants of this for a year, and
> watching my database grow to several tables of 100 million records, I
> need professional, high quality, in depth help.
>
> Thanks,
>
> Doug
>
>
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