Re: performance of temporary vs. regular tables

> As promised, I did a tiny benchmark - basically, 8 empty tables are
> filled with 100k rows each within 8 transactions (somewhat typically for
> my application). The test machine has 4 cores, 64G RAM and RAID1 10k
> drives for data.
>
> # INSERTs into a TEMPORARY table:
> [joachim(at)testsrv scaling]$ time pb query -d scaling_qry_1.xml
>
> real 3m18.242s
> user 1m59.074s
> sys 1m51.001s
>
> # INSERTs into a standard table:
> [joachim(at)testsrv scaling]$ time pb query -d scaling_qry_1.xml
>
> real 3m35.090s
> user 2m5.295s
> sys 2m2.307s
>
> Thus, there is a slight hit of about 10% (which may even be within
> meausrement variations) - your milage will vary.

Usually WAL causes a much larger performance hit than this.

Since the following command :

CREATE TABLE tmp AS SELECT n FROM generate_series(1,1000000) AS n

which inserts 1M rows takes 1.6 seconds on my desktop, your 800k rows
INSERT taking more than 3 minutes is a bit suspicious unless :

- you got huge fields that need TOASTing ; in this case TOAST compression
will eat a lot of CPU and you're benchmarking TOAST, not the rest of the
system
- you got some non-indexed foreign key
- some other reason ?