On Tuesday 29 December 2009 04:04:06 Michael Clemmons wrote: > Maybe not crash out but in this situation. > N=0 > while(N>=0): > CREATE DATABASE new_db_N; > Since the fsync is the part which takes the memory and time but is > happening in the background want the fsyncs pile up in the background > faster than can be run filling up the memory and stack. > This is very likely a mistake on my part about how postgres/processes The difference should not be visible outside the "CREATE DATABASE ..." at all. Currently the process simplifiedly works like: ------------ for file in source directory: copy_file(source/file, target/file); fsync(target/file); ------------ I changed it to: ------------- for file in source directory: copy_file(source/file, target/file); /*please dear kernel, write this out, but dont block*/ posix_fadvise(target/file, FADV_DONTNEED); for file in source directory: fsync(target/file); ------------- If at any point in time there is not enough cache available to cache anything copy_file() will just have to wait for the kernel to write out the data. fsync() does not use memory itself. Andres -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
