Thread: pgsql-server/src backend/executor/nodeAgg.c ba ...

pgsql-server/src backend/executor/nodeAgg.c ba ...

From
tgl@postgresql.org (Tom Lane)
Date:
CVSROOT:    /cvsroot
Module name:    pgsql-server
Changes by:    tgl@postgresql.org    02/11/19 18:22:00

Modified files:
    src/backend/executor: nodeAgg.c
    src/backend/nodes: copyfuncs.c equalfuncs.c
    src/backend/optimizer/plan: createplan.c initsplan.c planner.c
                                setrefs.c
    src/backend/utils/adt: selfuncs.c
    src/include/nodes: parsenodes.h
    src/include/optimizer: planmain.h
    src/include/utils: selfuncs.h

Log message:
    Add an at-least-marginally-plausible method of estimating the number
    of groups produced by GROUP BY.  This improves the accuracy of planning
    estimates for grouped subselects, and is needed to check whether a
    hashed aggregation plan risks memory overflow.