Обсуждение: pgsql/src backend/executor/nodeMergejoin.c bac ...

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pgsql/src backend/executor/nodeMergejoin.c bac ...

От
tgl@postgresql.org (Tom Lane)
Дата:
CVSROOT:    /cvsroot
Module name:    pgsql
Changes by:    tgl@postgresql.org    02/02/28 23:09:28

Modified files:
    src/backend/executor: nodeMergejoin.c
    src/backend/optimizer/path: costsize.c
    src/backend/utils/adt: selfuncs.c
    src/backend/utils/cache: lsyscache.c
    src/include/utils: lsyscache.h selfuncs.h

Log message:
    Teach planner about the idea that a mergejoin won't necessarily read
    both input streams to the end.  If one variable's range is much less
    than the other, an indexscan-based merge can win by not scanning all
    of the other table.  Per example from Reinhard Max.