Hi I am using Postgres8.3 on 8G memory , Xeon X5355 Quad Core x 2 processer RH5 machine with 10G data. (with some table which have about 2,000,000~ 5,000,000 rows ) I have two quesion. 1. how to set the shared_buffers and other postgresql.conf parameter for best performance? I only run the Postgres8.3 on the machine so I set the shared_buffers = 7168MB (7G) But somebody said it is too big, so confused. The memory info is that ----------------------------------------------------- MemTotal: 8177484 kB MemFree: 313336 kB Buffers: 112700 kB Cached: 7008160 kB SwapCached: 210832 kB Active: 7303660 kB Inactive: 402088 kB HighTotal: 0 kB HighFree: 0 kB LowTotal: 8177484 kB LowFree: 313336 kB SwapTotal: 8385920 kB SwapFree: 7415768 kB Dirty: 908 kB Writeback: 0 kB AnonPages: 28312 kB Mapped: 2163912 kB Slab: 99396 kB PageTables: 13004 kB NFS_Unstable: 0 kB Bounce: 0 kB CommitLimit: 12474660 kB Committed_AS: 8169440 kB VmallocTotal: 34359738367 kB VmallocUsed: 267136 kB VmallocChunk: 34359470587 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 Hugepagesize: 2048 kB ----------------------------------------------- 2 I have 8 core cpu ,but It seems that one sql can only use 1 core. Can I use more core to execute one sql to optimize the speed ? Thanks ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org