I am puzzled about the extent to which shared_bufferes is used for
different queries. Do _all_ queries "touch" shared buffers at some point
of their execution?
Many of our warehouse queries are seq_scan followed by HASH. I know
work_mem is assigned for HASH joins: but does this mean that these queries
never touch shared buffers at *all* during their execution? Perhaps they
are read into shared_buffers and then passed into work_mem HASH areas???
What about updates on big tables? What about inserts on big tables? What
about append-inserts?
I think I could get these answers from Explain Analyze Buffers but I am on
8.2 :-(
Please tell me which queries use/touch shared_buffers in general terms, or
please point me to documentation.
Shiv