Hello Craig: I want to know a sequential scan( full scan table) it can read how many blocks every io? I know scan index read is one block every io. Oracle parameter db_file_multiblock_read_count it can control scattered read (full scan table), assume db_file_multiblock_read_count =10,when scan full table,every io request blocks is 10 blocks. I know scan index read is one block every io.
So I want to when happen scan full table,postgresql scan full table scan how many blocks every io? Thank you! -----邮件原件----- 发件人: Craig Ringer [mailto:ring...@ringerc.id.au] 发送时间: 2012年7月27日 8:41 收件人: leo xu 抄送: pgsql-general@postgresql.org 主题: Re: [GENERAL] how to calculate or know seq_scan scan how many blocks every time On 07/25/2012 07:38 PM, leo xu wrote: > hello: > i know oracle scatter read blocks,can set > db_file_multiblock_read_count every time, > i see postgres,it exists scatter read blocks,it is seq_scan,how to > know scan many bloks every time? > If I understand correctly, you want to have a sequential scan read from more than one place at once. This is not currently supported. The effective_io_concurrency setting would be where you would set it, but it does not affect sequential scans at the moment. -- Craig Ringer -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
