You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

Tom Lane 9c7f5229ad Optimize joins when the inner relation can be proven unique. ... If there can certainly be no more than one matching inner row for a given outer row, then the executor can move on to the next outer row as soon as it's found one match; there's no need to continue scanning the inner relation for this outer row. This saves useless scanning in nestloop and hash joins. In merge joins, it offers the opportunity to skip mark/restore processing, because we know we have not advanced past the first possible match for the next outer row. Of course, the devil is in the details: the proof of uniqueness must depend only on joinquals (not otherquals), and if we want to skip mergejoin mark/restore then it must depend only on merge clauses. To avoid adding more planning overhead than absolutely necessary, the present patch errs in the conservative direction: there are cases where inner_unique or skip_mark_restore processing could be used, but it will not do so because it's not sure that the uniqueness proof depended only on "safe" clauses. This could be improved later. David Rowley, reviewed and rather heavily editorialized on by me Discussion: https://postgr.es/m/CAApHDvqF6Sw-TK98bW48TdtFJ+3a7D2mFyZ7++=D-RyPsL76gw@mail.gmail.com		8 years ago
..
expected	Optimize joins when the inner relation can be proven unique.	8 years ago
sql	Test all contrib-created operator classes with amvalidate.	9 years ago
.gitignore	Support "make check" in contrib	14 years ago
Makefile	Support the new regexp_match() function for citext.	9 years ago
citext--1.0--1.1.sql	Fix incorrect declaration of citext's regexp_matches() functions.	10 years ago
citext--1.1--1.2.sql	Schema-qualify some references to regprocedure.	9 years ago
citext--1.2--1.3.sql	Repair damage done by citext--1.1--1.2.sql.	9 years ago
citext--1.3--1.4.sql	Support the new regexp_match() function for citext.	9 years ago
citext--1.4.sql	Support the new regexp_match() function for citext.	9 years ago
citext--unpackaged--1.0.sql	Fix citext upgrade script for disallowance of oidvector element assignment.	11 years ago
citext.c	Move some things from builtins.h to new header files	9 years ago
citext.control	Support the new regexp_match() function for citext.	9 years ago