> I noticed that for each time the pgsql slow down, there is a short > period a process called "pdflush" eating up lot of I/O. I've goolgled > and know it is a process for writing dirty pages back to the disk by the > Linux kernel.
When i found the "pdflush" process is the major clue of PG slow down, i googled and found this article ! it is a really good one for tuning pdflush ! Thank a lot !
---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match