Thread: sort_mem affect on inserts?
I understand that the sort_mem conf setting affects queries with order by, etc., and the doc mentions that it is used increate index. Does sort_mem affect the updating of indexes, i.e., can the sort_mem setting affect the performance of inserts? - DAP ---------------------------------------------------------------------------------- David Parker Tazz Networks (401) 709-5130
David, > I understand that the sort_mem conf setting affects queries with order by, > etc., and the doc mentions that it is used in create index. Does sort_mem > affect the updating of indexes, i.e., can the sort_mem setting affect the > performance of inserts? Only if the table has Foriegn Keys whose lookup might require a large sort. Otherwise, no. -- --Josh Josh Berkus Aglio Database Solutions San Francisco
On 11/17/2004 5:07 PM, Josh Berkus wrote: > David, > >> I understand that the sort_mem conf setting affects queries with order by, >> etc., and the doc mentions that it is used in create index. Does sort_mem >> affect the updating of indexes, i.e., can the sort_mem setting affect the >> performance of inserts? > > Only if the table has Foriegn Keys whose lookup might require a large sort. > Otherwise, no. > Hmmm ... what type of foreign key lookup would that be? None of the RI generated queries has any order by clause. Jan -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck@Yahoo.com #
Jan, > Hmmm ... what type of foreign key lookup would that be? None of the RI > generated queries has any order by clause. I was under the impression that work_mem would be used for the index if there was an index for the RI lookup. Wrong? -- --Josh Josh Berkus Aglio Database Solutions San Francisco
Josh Berkus wrote: > I was under the impression that work_mem would be used for the index if there > was an index for the RI lookup. Wrong? Yes -- work_mem is not used for doing index scans, whether for RI lookups or otherwise. -Neil