From eed6c9ed7e243948e440ed1388591b7fa28f5827 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 5 Jun 2006 02:49:58 +0000 Subject: Add a GUC parameter seq_page_cost, and use that everywhere we formerly assumed that a sequential page fetch has cost 1.0. This patch doesn't in itself change the system's behavior at all, but it opens the door to people adopting other units of measurement for EXPLAIN costs. Also, if we ever decide it's worth inventing per-tablespace access cost settings, this change provides a workable intellectual framework for that. --- src/backend/utils/misc/postgresql.conf.sample | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'src/backend/utils/misc/postgresql.conf.sample') diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index d7f32256d11..0499223d110 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -175,12 +175,12 @@ # - Planner Cost Constants - +#seq_page_cost = 1.0 # measured on an arbitrary scale +#random_page_cost = 4.0 # same scale as above +#cpu_tuple_cost = 0.01 # same scale as above +#cpu_index_tuple_cost = 0.001 # same scale as above +#cpu_operator_cost = 0.0025 # same scale as above #effective_cache_size = 1000 # typically 8KB each -#random_page_cost = 4 # units are one sequential page fetch - # cost -#cpu_tuple_cost = 0.01 # (same) -#cpu_index_tuple_cost = 0.001 # (same) -#cpu_operator_cost = 0.0025 # (same) # - Genetic Query Optimizer - -- cgit v1.2.3