Thread: pgsql: Share transition state between different aggregates when possibl
pgsql: Share transition state between different aggregates when possibl
From
Heikki Linnakangas
Date:
Share transition state between different aggregates when possible. If there are two different aggregates in the query with same inputs, and the aggregates have the same initial condition and transition function, only calculate the state value once, and only call the final functions separately. For example, AVG(x) and SUM(x) aggregates have the same transition function, which accumulates the sum and number of input tuples. For a query like "SELECT AVG(x), SUM(x) FROM x", we can therefore accumulate the state function only once, which gives a nice speedup. David Rowley, reviewed and edited by me. Branch ------ master Details ------- http://git.postgresql.org/pg/commitdiff/804163bc25e979fcd91b02e58fa2d1c6b587cc65 Modified Files -------------- src/backend/executor/execQual.c | 22 +- src/backend/executor/nodeAgg.c | 1070 +++++++++++++++++++----------- src/backend/executor/nodeWindowAgg.c | 31 +- src/backend/parser/parse_agg.c | 75 ++- src/include/nodes/execnodes.h | 8 +- src/include/parser/parse_agg.h | 14 +- src/test/regress/expected/aggregates.out | 204 ++++++ src/test/regress/sql/aggregates.sql | 165 +++++ 8 files changed, 1132 insertions(+), 457 deletions(-)