Log Message: ----------- Improve SELECT DISTINCT to consider hash aggregation, as well as sort/uniq, as methods for implementing the DISTINCT step. This eliminates the former performance gap between DISTINCT and GROUP BY, and also makes it possible to do SELECT DISTINCT on datatypes that only sup****t ha****ng not sorting. SELECT DISTINCT ON is still always implemented by sorting; it would take executor changes to sup****t ha****ng that, and it's not clear it's worth the trouble. This is a release-note-worthy incompatibility from previous PG versions, since SELECT DISTINCT can no longer be counted on to deliver sorted output without explicitly saying ORDER BY. (Anyone who can't cope with that can consider turning off enable_hashagg.) Several regression test queries needed to have ORDER BY added to preserve stable output order. I fixed the ones that manifested here, but there might be some other cases that show up on other platforms. Modified Files: -------------- pgsql/src/backend/nodes: outfuncs.c (r1.329 -> r1.330) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/outfuncs.c?r1=1.329&r2=1.330) pgsql/src/backend/optimizer/plan: planmain.c (r1.108 -> r1.109) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planmain.c?r1=1.108&r2=1.109) planner.c (r1.237 -> r1.238) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planner.c?r1=1.237&r2=1.238) pgsql/src/backend/parser: parse_clause.c (r1.173 -> r1.174) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_clause.c?r1=1.173&r2=1.174) pgsql/src/include/nodes: relation.h (r1.156 -> r1.157) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/relation.h?r1=1.156&r2=1.157) pgsql/src/test/regress/expected: numerology.out (r1.4 -> r1.5) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/numerology.out?r1=1.4&r2=1.5) opr_sanity.out (r1.82 -> r1.83) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/opr_sanity.out?r1=1.82&r2=1.83) select_distinct.out (r1.5 -> r1.6) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/select_distinct.out?r1=1.5&r2=1.6) pgsql/src/test/regress/input: misc.source (r1.21 -> r1.22) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/input/misc.source?r1=1.21&r2=1.22) pgsql/src/test/regress/output: misc.source (r1.46 -> r1.47) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/output/misc.source?r1=1.46&r2=1.47) pgsql/src/test/regress/sql: numerology.sql (r1.4 -> r1.5) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/numerology.sql?r1=1.4&r2=1.5) opr_sanity.sql (r1.66 -> r1.67) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/opr_sanity.sql?r1=1.66&r2=1.67) select_distinct.sql (r1.5 -> r1.6) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/select_distinct.sql?r1=1.5&r2=1.6) -- Sent via pgsql-committers mailing list (pgsql-committers@[EMAIL PROTECTED] ) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
