Performance Concern

From: "John Pagakis" <john(at)pagakis(dot)com>
To: <pgsql-performance(at)postgresql(dot)org>
Subject: Performance Concern
Date: 2003-10-23 12:21:03
Message-ID: KKEBKDPPLALEFHBEAOCCGEBLDEAA.john@pagakis.com
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Greetings.

I have a table that will require 100,000 rows initially.

Assume the following (some of the field names have been changed for
confidentiality reasons):

CREATE TABLE baz (
baz_number CHAR(15) NOT NULL,
customer_id CHAR(39),
foobar_id INTEGER,
is_cancelled BOOL DEFAULT false NOT NULL,
create_user VARCHAR(60) NOT NULL,
create_datetime TIMESTAMP DEFAULT 'now()' NOT NULL,
last_update_user VARCHAR(60) NOT NULL,
last_update_datetime TIMESTAMP DEFAULT 'now()' NOT NULL,
CONSTRAINT PK_baz PRIMARY KEY (baz_number)
);

ALTER TABLE baz
ADD FOREIGN KEY (customer_id) REFERENCES purchase (customer_id);

ALTER TABLE baz
ADD FOREIGN KEY (foobar_id) REFERENCES foobar (foobar_id);

Using JDBC, it took approximately one hour to insert 100,000 records. I
have an algorithm to generate a unique baz_number - it is a mixture of alpha
and numerics.

There is a purchase table; one purchase can have many associated baz
records, but the baz records will be pre-allocated - baz.customer_id allows
null. The act of purchasing a baz will cause baz.customer_id to be
populated from the customer_id (key) field in the purchase table.

If it took an hour to insert 100,000 records, I can only imagine how much
time it will take if one customer were to attempt to purchase all 100,000
baz. Certainly too long for a web page.

I've not had to deal with this kind of volume in Postgres before; I have my
suspicions on what is wrong here (could it be using a CHAR( 15 ) as a key?)
but I'd *LOVE* any thoughts.

Would I be better off making the key an identity field and not indexing on
baz_number?

Thanks in advance for any help.

__________________________________________________________________
John Pagakis
Email: ih8spam_thebfh(at)toolsmythe(dot)com

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-- Paul Valery

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