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author | Tom Lane <tgl@sss.pgh.pa.us> | 2003-01-24 03:58:44 +0000 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2003-01-24 03:58:44 +0000 |
commit | f5e83662d06a40f90ceb3516fc88674eb6c1e4f9 (patch) | |
tree | 5b682c9bcbc9dd88b7bcc19f1ca1bf43c8335a83 /src/backend/utils/adt/sets.c | |
parent | ef7422510e93266e5aa9bb926d6747d5f2ae21f4 (diff) | |
download | postgresql-f5e83662d06a40f90ceb3516fc88674eb6c1e4f9.tar.gz postgresql-f5e83662d06a40f90ceb3516fc88674eb6c1e4f9.zip |
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/sets.c')
0 files changed, 0 insertions, 0 deletions