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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2006-06-05 02:49:58 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2006-06-05 02:49:58 +0000 |
| commit | eed6c9ed7e243948e440ed1388591b7fa28f5827 (patch) | |
| tree | aef8821bdd57ed83e2c1b2ce27014e45beed0934 /src/backend/utils/misc/postgresql.conf.sample | |
| parent | a837851dc060515c1f7023f74d75156a80c2c936 (diff) | |
| download | postgresql-eed6c9ed7e243948e440ed1388591b7fa28f5827.tar.gz postgresql-eed6c9ed7e243948e440ed1388591b7fa28f5827.zip | |
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.
Diffstat (limited to 'src/backend/utils/misc/postgresql.conf.sample')
| -rw-r--r-- | src/backend/utils/misc/postgresql.conf.sample | 10 |
1 files changed, 5 insertions, 5 deletions
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 - |