Re: TRUNCATE TABLE - Mailing list pgsql-performance

From Adriaan van Os
Subject Re: TRUNCATE TABLE
Date
Msg-id 469DC30D.3060603@microbizz.nl
Whole thread Raw
In response to Re: TRUNCATE TABLE  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
Tom Lane wrote:

> Thus the timing issue (at least as exhibited by this script) has nothing
> whatever to do with the time to delete a file, but with the time to
> create one.  Since the part of DROP being timed has probably got no I/O
> involved at all (the tuples being touched are almost surely still in
> shared buffers), it's unsurprising that it is consistently fast.

In my original profiling, CREATE TEMPORARY TABLE/DROP TABLE wasn't much faster than TRUNCATE TABLE.
When I try it again now, I see that DROP TABLE is consistently fast, while the timings of CREATE
TEMPORARY TABLE vary as much as those of TRUNCATE TABLE. Your observations on the time needed to
open a file confirm that, I think.

In my test databases, autovacuum is off.

Regards,

Adriaan van Os

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