Re: slow update on 1M rows (worse with indexes)

n i tried adding an index to the table on the column date (int) that
> stores unix timestamps.
> TOTO=# CREATE INDEX versions_index ON versions_9d (date);
> (-60M) disk space goes down on index creation
> beebox(at)evobrik01:~$ time psql TOTO -c "UPDATE versions_9d SET flag=9"
> UPDATE 976009
> real 3m8.219s (+328M)
> beebox(at)evobrik01:~$ time psql TOTO -c "UPDATE versions_9d SET flag=8"
> UPDATE 976009
> real 6m24.716s (+326M)
> beebox(at)evobrik01:~$ time psql TOTO -c "UPDATE versions_9d SET flag=10"
> UPDATE 976009
> real 8m25.274s (+321M)
>
> As a sanity check, i loaded mysql5 and tried the same database and
> updates. With mysql, the update always lasts ~8s.

Yes but with mysql did you use myisam or innodb?

> The conclusions I have come to is that update==insert+delete which seems
> very heavy when index are present (and heavy disk wise on big tables).
> Is there a switch i can flip to optimise this?
>
> Thanks in advance,
> Gabriel Biberian
>
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