For temporary tables; truncate vs on commit delete all
Does anyone have any idea which is generally better (by better I mean
most efficient/quickest!) in this simple scenario? I have a temporary
table which I wish to retain for the duration of a long-running
session. However, for each transaction it must be purged. So, is it
better to;
a) Always CREATE TEMPORARY TABLE + ON COMMIT DROP for every transaction or;
b) TRUNCATE TABLE or;
c) ON COMMIT DELETE ROWS
Both b & c avoid re-creating the table each time but at the cost of an
explicit purge of some form.
I would assume that despite its name, the latter, example c, is more
akin to a truncation? Or does it actually perform a deletion?
Cheers
Jim
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Jim Vanns
Principal Production Engineer
Industrial Light & Magic, London
On Wed, 2023-03-22 at 11:59 +0000, Jim Vanns wrote:
Does anyone have any idea which is generally better (by better I mean
most efficient/quickest!) in this simple scenario? I have a temporary
table which I wish to retain for the duration of a long-running
session. However, for each transaction it must be purged. So, is it
better to;a) Always CREATE TEMPORARY TABLE + ON COMMIT DROP for every transaction or;
b) TRUNCATE TABLE or;
c) ON COMMIT DELETE ROWSBoth b & c avoid re-creating the table each time but at the cost of an
explicit purge of some form.
I would assume that despite its name, the latter, example c, is more
akin to a truncation? Or does it actually perform a deletion?
b) or c) are best.
Yes, ON COMMIT DELETE ROWS will truncate the temporary table.
Creating too many temporary tables in a short time can lead to bloat
in "pg_attribute".
Yours,
Laurenz Albe
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