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authorTom Lane <tgl@sss.pgh.pa.us>2003-01-24 03:58:44 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2003-01-24 03:58:44 +0000
commitf5e83662d06a40f90ceb3516fc88674eb6c1e4f9 (patch)
tree5b682c9bcbc9dd88b7bcc19f1ca1bf43c8335a83 /src/backend/utils/adt/oid.c
parentef7422510e93266e5aa9bb926d6747d5f2ae21f4 (diff)
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Modify planner's implied-equality-deduction code so that when a set
of known-equal expressions includes any constant expressions (including Params from outer queries), we actively suppress any 'var = var' clauses that are or could be deduced from the set, generating only the deducible 'var = const' clauses instead. The idea here is to push down the restrictions implied by the equality set to base relations whenever possible. Once we have applied the 'var = const' clauses, the 'var = var' clauses are redundant, and should be suppressed both to save work at execution and to avoid double-counting restrictivity.
Diffstat (limited to 'src/backend/utils/adt/oid.c')
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