Στις Tuesday 08 July 2008 21:34:01 ο/η Tom Lane έγραψε: > Achilleas Mantzios <achill@xxxxxxxxxxxxxxxxxxxxx> writes: > > Στις Tuesday 08 July 2008 17:35:16 ο/η Tom Lane έγραψε: > >> Hmm. There's a function in elog.c that breaks log messages into chunks > >> for syslog. I don't think anyone's ever looked hard at its performance > >> --- maybe there's an O(N^2) behavior? > > > > Thanx, > > i changed PG_SYSLOG_LIMIT in elog.c:1269 from 128 to 1048576 > > and i got super fast stderr performance. :) > > Doesn't seem like a very good solution given its impact on the stack > depth right there. > > Looking at the code, the only bit that looks like repeated work are the > repeated calls to strchr(), which would not be an issue in the "typical" > case where the very long message contains reasonably frequent newlines. > Am I right in guessing that your problematic statement contained > megabytes worth of text with nary a newline? Yes it was the input source of a bytea field containing tiff or pdf data, of size of some 1-3 megabytes, and it did not contain (many) newlines. > > If so, we can certainly fix it by arranging to remember the last > strchr() result across loop iterations, but I'd like to confirm the > theory before doing that work. > > regards, tom lane
