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Subject: Re: Insert performance for large transaction with multiple COPY FROM
From: Horst Dehmer <horst.dehmer@gmail.com>
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 <CAGTBQpavK111WhRZYk1pfRsv3ixn-VnQKD1EZbbD=Yg-y4pZ+Q@mail.gmail.com>
Date: Sat, 12 Jan 2013 21:16:02 +0100
Cc: postgres performance list <pgsql-performance@postgresql.org>
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	<CAGTBQpavK111WhRZYk1pfRsv3ixn-VnQKD1EZbbD=Yg-y4pZ+Q@mail.gmail.com>
To: Claudio Freire <klaussfreire@gmail.com>
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Yes, the ids is something I don't like either.
They carry additional semantics, which I cannot make go away.
How are chances char(20) is more time efficient than numeric(20)?
Disk space is no problem here.


On 12.01.2013, at 02:17, Claudio Freire <klaussfreire@gmail.com> wrote:

> On Fri, Jan 11, 2013 at 8:55 PM, Horst Dehmer <horst.dehmer@gmail.com> wr=
ote:
>> Except - and that's the wall I'm hitting - for one table which yielded j=
ust
>> 75 records/second.
>> The main 'problem' seem to be the FK constraints. Dropping just them
>> restored insert performance for this table to 6k records/s. The table in
>> question has a composite PK (3 columns), 3 foreign keys and a bunch of
>> indexes (see table obj_item_loc at the end of the mail). Compared to the
>> other 32 tables nothing unusual.
>> I'd gladly supply more information if necessary.
> ...
>> CREATE TABLE obj_item_loc
>> (
>>  obj_item_id numeric(20,0) NOT NULL,
>>  loc_id numeric(20,0) NOT NULL,
>>  obj_item_loc_ix numeric(20,0) NOT NULL,
>=20
> That sounds a lot like a missing index on the target relations (or
> indices that are unusable).
>=20
> Those numeric ids look really unusual. Why not bigint? It's close to
> the same precision, but native, faster, more compact, and quite
> unambiguous when indices are involved. If the types don't match on
> both tables, it's quite likely indices won't be used when checking the
> FK, and that spells trouble.


--=20
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