Thread: pgsql: Remove 'additional' pointer from TupleHashEntryData.

Remove 'additional' pointer from TupleHashEntryData.

Reduces memory required for hash aggregation by avoiding an allocation
and a pointer in the TupleHashEntryData structure. That structure is
used for all buckets, whether occupied or not, so the savings is
substantial.

Discussion: https://postgr.es/m/AApHDvpN4v3t_sdz4dvrv1Fx_ZPw=twSnxuTEytRYP7LFz5K9A@mail.gmail.com
Reviewed-by: David Rowley <dgrowleyml@gmail.com>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/626df47ad9db809dc8f93330175ab95b75914721

Modified Files
--------------
src/backend/executor/execGrouping.c | 17 ++++++++++++-----
src/include/executor/executor.h     |  5 ++++-
src/include/nodes/execnodes.h       |  1 -
3 files changed, 16 insertions(+), 7 deletions(-)