On Wed, Sep 14, 2022 at 05:02:07PM +0200, tiaswin@xxxxxx wrote: > <html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>What could be the reason of a query, which is sometimes fast and sometimes slow (factor >10x)?</div> > <div>(running on a large table).</div> > <div> </div> > <div> </div></div></body></html> Lots of possible issues. Is it using a different query plan ? Collect a good plan and a bad one and compare, or send both. Perhaps use autoexplain to do so. Turn on logging and send as much information as you can as described here. https://wiki.postgresql.org/wiki/Slow_Query_Questions Please try to configure your mail client to send text mail (instead of or in addition to the html one). -- Justin
