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Tom Lane 9233624b12 Clamp total-tuples estimates for foreign tables to ensure planner sanity. ... After running GetForeignRelSize for a foreign table, adjust rel->tuples to be at least as large as rel->rows. This prevents bizarre behavior in estimate_num_groups() and perhaps other places, especially in the scenario where rel->tuples is zero because pg_class.reltuples is (suggesting that ANALYZE has never been run for the table). As things stood, we'd end up estimating one group out of any GROUP BY on such a table, whereas the default group-count estimate is more likely to result in a sane plan. Also, clarify in the documentation that GetForeignRelSize has the option to override the rel->tuples value if it has a better idea of what to use than what is in pg_class.reltuples. Per report from Jeff Janes. Back-patch to all supported branches. Patch by me; thanks to Etsuro Fujita for review Discussion: https://postgr.es/m/CAMkU=1xNo9cnan+Npxgz0eK7394xmjmKg-QEm8wYG9P5-CcaqQ@mail.gmail.com		5 years ago
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src	Clamp total-tuples estimates for foreign tables to ensure planner sanity.	5 years ago
KNOWN_BUGS	…
MISSING_FEATURES	…
Makefile	…
TODO	Change documentation references to PG website to use https: not http:	8 years ago