Hello together, I need to increase the write performance when inserting bytea of 8MB. I am using 8.2.4 on windows with libpq. The test setting is simple: I write 100x times a byte array (bytea) of 8 MB random data into a table having a binary column (and oids and 3 other int columns, oids are indexed). I realized that writing 8 MB of 0-bytes is optimized away. With random data, the disk space now is filled with 800MB each run as expected. I use a transaction around the insert command. This takes about 50s, so, 800MB/50s = 16MB/s. However the harddisk (sata) could write 43 MB/s in the worst case! Why is write performance limited to 16 MB/s? Some more hints what I do: I use PQexecParams() and the INSERT ... $001 notation to NOT create a real escapted string from the data additionally but use a pointer to the 8MB data buffer. I altered the binary column to STORAGE EXTERNAL. Some experiments with postgresql.conf (fsync off, shared_buffers=1000MB, checkpoint_segments=256) did not change the 50s- much (somtimes 60s sometimes a little less). 4 Core CPU 3 Ghz, WinXP, 1 TB SATA disk. Do you have any further idea why 16MB/s seems to be the limit here? Thank You Felix -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
