--On Sunday, May 17, 2009 11:56:35 PM -0700 Howard Chu hyc@symas.com wrote:
However, on BDB 4.7 it seems the default behavior on Linux is also to do synchronous flushes of the cache. As such, one approach to getting consistent performance is to configure the backend to use shared memory for the BDB cache instead of mmap'd files. That way incidental page updates don't sync to anything, and the BDB library has full control over when pages get flushed back to disk.
We can confirm that setting shm_key on 4.7 dramatically affects the load time. In our initial tests of 4.7 we just pulled our old 4.2 BDB parameters forward. We never saw the slapadd of a 4.6 gbyte database complete. We killed it after 4 hours. After changing the shm_key setting the load time dropped to the more normal 30 minutes.
Bill