Is it a memory leak in PostgreSQL 7.4beta?

I have done some beta testing with PostgreSQL 7.4beta2.
I have run a simple set of SQL statements 1 million times:

-- START TRANSACTION ISOLATION LEVEL READ COMMITTED;
INSERT INTO t_data (data) VALUES ('2500');
UPDATE t_data SET data = '2500' WHERE data = '2500';
DELETE FROM t_data WHERE data = '2500';
-- COMMIT;

The interesting thing was that my postmaster needed around 4mb of RAM
when I started running my test script using ...

psql test < script.sql

After about 2 1/2 hours the backend process already needed 11mb of ram.
looking at the output of top you can see that it seems to be in the
shared memory area:

PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME
COMMAND
28899 hs 39 19 11456 11M 10620 R N 89.8 2.9
150:23 postmaster

this seems very surprising to me because I have no explanation why
PostgreSQL should consume so much more memory than at the beginning of
the test.
There are no trigger or something like that around.

The table I am working on consist of two columns (one timestamp, one int4).

In addition to that I have made a test with a different set of SQL
statements. I have tried 1500 concurrent transaction on my good old AMD
Athlon 500 box running RedHat Linux. It worked out pretty fine. The
thing I came across was that my memory consumption raised during the
first two hours of my test (from about 1 1/2 gigs to 1.7 gigs ram).
pretty surprising as well.

does anybody have an explanation for this behaviour?

Regards,

Hans

I have run 1500 concurrent transactions on an AMD Athlon box (RedHat 9).

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