On Sun, Oct 4, 2015 at 1:12 PM, Peter Geoghegan <p...@heroku.com> wrote: > On Sun, Oct 4, 2015 at 1:01 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> Ah, right, sorry. I meant to make its result match what gc_texts would >> get, by not falsely counting entries with dropped texts. That's not >> what you have in your patch but it seems like an easy enough fix. > > I'm trying to make mean_query_len representative of *useful* entry > query length. I guess I don't have that within gc_texts in my patch, > but I do have it within entry_dealloc (up to and including considering > dropped texts), which FWIW is far more important.
To be clear: I wasn't sure why you though I falsely count entries with dropped texts within entry_dealloc(). I suppose my sense was that dropped texts ought to not make garbage collection occur too frequently, which could also be a problem. Garbage collection ought to occur when the size of the query text file becomes excessive relative to useful entries. I was worried about the thrashing risk from dropped text entries. Maybe we could, as an alternative, not forget the original size of dropped query texts, relying only on their offset to indicate the text is invalid. Dropped query texts would then not be special in that sense, which seems like a good thing all around. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
