0f0deb7194
Currently, if operator_predicate_proof() is given an operator clause like "something op NULL", it just throws up its hands and reports it can't prove anything. But we can often do better than that, if the operator is strict, because then we know that the clause returns NULL overall. Depending on whether we're trying to prove or refute something, and whether we need weak or strong semantics for NULL, this may be enough to prove the implication, especially when we rely on the standard rule that "false implies anything". In particular, this lets us do something useful with questions like "does X IN (1,3,5,NULL) imply X <= 5?" The null entry in the IN list can effectively be ignored for this purpose, but the proof rules were not previously smart enough to deduce that. This patch is by me, but it owes something to previous work by Amit Langote to try to solve problems of the form mentioned. Thanks also to Emre Hasegeli and Ashutosh Bapat for review. Discussion: https://postgr.es/m/3bad48fc-f257-c445-feeb-8a2b2fb622ba@lab.ntt.co.jp |
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| .. | ||
| data | ||
| expected | ||
| input | ||
| output | ||
| sql | ||
| .gitignore | ||
| GNUmakefile | ||
| Makefile | ||
| README | ||
| parallel_schedule | ||
| pg_regress.c | ||
| pg_regress.h | ||
| pg_regress_main.c | ||
| regress.c | ||
| regressplans.sh | ||
| resultmap | ||
| serial_schedule | ||
| standby_schedule | ||
README
Documentation concerning how to run these regression tests and interpret the results can be found in the PostgreSQL manual, in the chapter "Regression Tests".