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expression eval: Reduce number of steps for agg transition invocations.

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Do so by combining the various steps that are part of aggregate
transition function invocation into one larger step. As some of the
current steps are only necessary for some aggregates, have one variant
of the aggregate transition step for each possible combination.

To avoid further manual copies of code in the different transition
step implementations, move most of the code into helper functions
marked as "always inline".

The benefit of this change is an increase in performance when
aggregating lots of rows. This comes in part due to the reduced number
of indirect jumps due to the reduced number of steps, and in part by
reducing redundant setup code across steps. This mainly benefits
interpreted execution, but the code generated by JIT is also improved
a bit.

As a nice side-effect it also ends up making the code a bit simpler.

A small additional optimization is removing the need to set
aggstate->curaggcontext before calling ExecAggInitGroup, choosing to
instead passign curaggcontext as an argument. It was, in contrast to
other aggregate related functions, only needed to fetch a memory
context to copy the transition value into.

Author: Andres Freund
Discussion:
   https://postgr.es/m/20191023163849.sosqbfs5yenocez3@alap3.anarazel.de
   https://postgr.es/m/5c371df7cee903e8cd4c685f90c6c72086d3a2dc.camel@j-davis.com
This commit is contained in:
Andres Freund
2020-02-24 14:39:22 -08:00
parent 7d672b76bf
commit 2742c45080
5 changed files with 351 additions and 367 deletions
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34
src/include/executor/execExpr.h
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@@ -225,10 +225,12 @@ typedef enum ExprEvalOp
EEOP_AGG_DESERIALIZE,
EEOP_AGG_STRICT_INPUT_CHECK_ARGS,
EEOP_AGG_STRICT_INPUT_CHECK_NULLS,
EEOP_AGG_INIT_TRANS,
EEOP_AGG_STRICT_TRANS_CHECK,
EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL,
EEOP_AGG_PLAIN_TRANS_STRICT_BYVAL,
EEOP_AGG_PLAIN_TRANS_BYVAL,
EEOP_AGG_PLAIN_TRANS,
EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF,
EEOP_AGG_PLAIN_TRANS_STRICT_BYREF,
EEOP_AGG_PLAIN_TRANS_BYREF,
EEOP_AGG_ORDERED_TRANS_DATUM,
EEOP_AGG_ORDERED_TRANS_TUPLE,
@@ -620,27 +622,8 @@ typedef struct ExprEvalStep
int jumpnull;
} agg_strict_input_check;
/* for EEOP_AGG_INIT_TRANS */
struct
{
AggStatePerTrans pertrans;
ExprContext *aggcontext;
int setno;
int transno;
int setoff;
int jumpnull;
} agg_init_trans;
/* for EEOP_AGG_STRICT_TRANS_CHECK */
struct
{
int setno;
int transno;
int setoff;
int jumpnull;
} agg_strict_trans_check;
/* for EEOP_AGG_{PLAIN,ORDERED}_TRANS* */
/* for EEOP_AGG_PLAIN_TRANS_[INIT_][STRICT_]{BYVAL,BYREF} */
/* for EEOP_AGG_ORDERED_TRANS_{DATUM,TUPLE} */
struct
{
AggStatePerTrans pertrans;
@@ -750,7 +733,8 @@ extern void ExecEvalWholeRowVar(ExprState *state, ExprEvalStep *op,
extern void ExecEvalSysVar(ExprState *state, ExprEvalStep *op,
ExprContext *econtext, TupleTableSlot *slot);
extern void ExecAggInitGroup(AggState *aggstate, AggStatePerTrans pertrans, AggStatePerGroup pergroup);
extern void ExecAggInitGroup(AggState *aggstate, AggStatePerTrans pertrans, AggStatePerGroup pergroup,
ExprContext *aggcontext);
extern Datum ExecAggTransReparent(AggState *aggstate, AggStatePerTrans pertrans,
Datum newValue, bool newValueIsNull,
Datum oldValue, bool oldValueIsNull);