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Allow the planner to collapse explicit inner JOINs together, rather than

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necessarily following the JOIN syntax to develop the query plan.  The old
behavior is still available by setting GUC variable JOIN_COLLAPSE_LIMIT
to 1.  Also create a GUC variable FROM_COLLAPSE_LIMIT to control the
similar decision about when to collapse sub-SELECT lists into their parent
lists.  (This behavior existed already, but the limit was always
GEQO_THRESHOLD/2; now it's separately adjustable.)
This commit is contained in:
Tom Lane
2003-01-25 23:10:30 +00:00
parent 15ab7a8720
commit 9f5f212475
12 changed files with 1035 additions and 873 deletions
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3
src/backend/utils/misc/postgresql.conf.sample
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@ -94,6 +94,9 @@
#cpu_index_tuple_cost = 0.001 # (same)
#cpu_operator_cost = 0.0025 # (same)
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit JOINs
#default_statistics_target = 10 # range 1-1000
#