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expression eval: Reduce number of steps for agg transition invocations.
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
@ -166,6 +166,16 @@ static Datum ExecJustAssignInnerVarVirt(ExprState *state, ExprContext *econtext,
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static Datum ExecJustAssignOuterVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
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static Datum ExecJustAssignScanVarVirt(ExprState *state, ExprContext *econtext, bool *isnull);
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/* execution helper functions */
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static pg_attribute_always_inline void
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ExecAggPlainTransByVal(AggState *aggstate, AggStatePerTrans pertrans,
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AggStatePerGroup pergroup,
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ExprContext *aggcontext, int setno);
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static pg_attribute_always_inline void
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ExecAggPlainTransByRef(AggState *aggstate, AggStatePerTrans pertrans,
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AggStatePerGroup pergroup,
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ExprContext *aggcontext, int setno);
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/*
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* Prepare ExprState for interpreted execution.
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@ -425,10 +435,12 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
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&&CASE_EEOP_AGG_DESERIALIZE,
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&&CASE_EEOP_AGG_STRICT_INPUT_CHECK_ARGS,
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&&CASE_EEOP_AGG_STRICT_INPUT_CHECK_NULLS,
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&&CASE_EEOP_AGG_INIT_TRANS,
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&&CASE_EEOP_AGG_STRICT_TRANS_CHECK,
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&&CASE_EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL,
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&&CASE_EEOP_AGG_PLAIN_TRANS_STRICT_BYVAL,
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&&CASE_EEOP_AGG_PLAIN_TRANS_BYVAL,
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&&CASE_EEOP_AGG_PLAIN_TRANS,
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&&CASE_EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF,
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&&CASE_EEOP_AGG_PLAIN_TRANS_STRICT_BYREF,
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&&CASE_EEOP_AGG_PLAIN_TRANS_BYREF,
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&&CASE_EEOP_AGG_ORDERED_TRANS_DATUM,
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&&CASE_EEOP_AGG_ORDERED_TRANS_TUPLE,
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&&CASE_EEOP_LAST
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@ -1592,167 +1604,136 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
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}
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/*
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* Initialize an aggregate's first value if necessary.
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* Different types of aggregate transition functions are implemented
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* as different types of steps, to avoid incurring unnecessary
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* overhead. There's a step type for each valid combination of having
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* a by value / by reference transition type, [not] needing to the
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* initialize the transition value for the first row in a group from
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* input, and [not] strict transition function.
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*
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* Could optimize further by splitting off by-reference for
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* fixed-length types, but currently that doesn't seem worth it.
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*/
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EEO_CASE(EEOP_AGG_INIT_TRANS)
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EEO_CASE(EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerGroup pergroup;
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pergroup = &aggstate->all_pergroups
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[op->d.agg_init_trans.setoff]
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[op->d.agg_init_trans.transno];
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/* If transValue has not yet been initialized, do so now. */
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if (pergroup->noTransValue)
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{
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AggStatePerTrans pertrans = op->d.agg_init_trans.pertrans;
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aggstate->curaggcontext = op->d.agg_init_trans.aggcontext;
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aggstate->current_set = op->d.agg_init_trans.setno;
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ExecAggInitGroup(aggstate, pertrans, pergroup);
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/* copied trans value from input, done this round */
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EEO_JUMP(op->d.agg_init_trans.jumpnull);
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}
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EEO_NEXT();
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}
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/* check that a strict aggregate's input isn't NULL */
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EEO_CASE(EEOP_AGG_STRICT_TRANS_CHECK)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerGroup pergroup;
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pergroup = &aggstate->all_pergroups
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[op->d.agg_strict_trans_check.setoff]
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[op->d.agg_strict_trans_check.transno];
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if (unlikely(pergroup->transValueIsNull))
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EEO_JUMP(op->d.agg_strict_trans_check.jumpnull);
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EEO_NEXT();
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}
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/*
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* Evaluate aggregate transition / combine function that has a
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* by-value transition type. That's a separate case from the
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* by-reference implementation because it's a bit simpler.
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*/
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EEO_CASE(EEOP_AGG_PLAIN_TRANS_BYVAL)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerTrans pertrans;
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AggStatePerGroup pergroup;
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FunctionCallInfo fcinfo;
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MemoryContext oldContext;
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Datum newVal;
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pertrans = op->d.agg_trans.pertrans;
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pergroup = &aggstate->all_pergroups
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AggStatePerTrans pertrans = op->d.agg_trans.pertrans;
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AggStatePerGroup pergroup = &aggstate->all_pergroups
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[op->d.agg_trans.setoff]
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[op->d.agg_trans.transno];
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Assert(pertrans->transtypeByVal);
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fcinfo = pertrans->transfn_fcinfo;
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/* cf. select_current_set() */
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aggstate->curaggcontext = op->d.agg_trans.aggcontext;
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aggstate->current_set = op->d.agg_trans.setno;
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/* set up aggstate->curpertrans for AggGetAggref() */
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aggstate->curpertrans = pertrans;
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/* invoke transition function in per-tuple context */
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oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
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fcinfo->args[0].value = pergroup->transValue;
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fcinfo->args[0].isnull = pergroup->transValueIsNull;
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fcinfo->isnull = false; /* just in case transfn doesn't set it */
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newVal = FunctionCallInvoke(fcinfo);
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pergroup->transValue = newVal;
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pergroup->transValueIsNull = fcinfo->isnull;
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MemoryContextSwitchTo(oldContext);
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if (pergroup->noTransValue)
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{
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/* If transValue has not yet been initialized, do so now. */
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ExecAggInitGroup(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext);
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/* copied trans value from input, done this round */
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}
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else if (likely(!pergroup->transValueIsNull))
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{
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/* invoke transition function, unless prevented by strictness */
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ExecAggPlainTransByVal(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext,
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op->d.agg_trans.setno);
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}
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EEO_NEXT();
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}
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/*
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* Evaluate aggregate transition / combine function that has a
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* by-reference transition type.
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*
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* Could optimize a bit further by splitting off by-reference
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* fixed-length types, but currently that doesn't seem worth it.
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*/
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EEO_CASE(EEOP_AGG_PLAIN_TRANS)
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/* see comments above EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL */
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EEO_CASE(EEOP_AGG_PLAIN_TRANS_STRICT_BYVAL)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerTrans pertrans;
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AggStatePerGroup pergroup;
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FunctionCallInfo fcinfo;
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MemoryContext oldContext;
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Datum newVal;
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AggStatePerTrans pertrans = op->d.agg_trans.pertrans;
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AggStatePerGroup pergroup = &aggstate->all_pergroups
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[op->d.agg_trans.setoff]
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[op->d.agg_trans.transno];
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pertrans = op->d.agg_trans.pertrans;
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Assert(pertrans->transtypeByVal);
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pergroup = &aggstate->all_pergroups
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if (likely(!pergroup->transValueIsNull))
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ExecAggPlainTransByVal(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext,
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op->d.agg_trans.setno);
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EEO_NEXT();
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}
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/* see comments above EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL */
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EEO_CASE(EEOP_AGG_PLAIN_TRANS_BYVAL)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerTrans pertrans = op->d.agg_trans.pertrans;
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AggStatePerGroup pergroup = &aggstate->all_pergroups
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[op->d.agg_trans.setoff]
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[op->d.agg_trans.transno];
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Assert(pertrans->transtypeByVal);
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ExecAggPlainTransByVal(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext,
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op->d.agg_trans.setno);
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EEO_NEXT();
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}
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/* see comments above EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL */
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EEO_CASE(EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerTrans pertrans = op->d.agg_trans.pertrans;
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AggStatePerGroup pergroup = &aggstate->all_pergroups
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[op->d.agg_trans.setoff]
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[op->d.agg_trans.transno];
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Assert(!pertrans->transtypeByVal);
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fcinfo = pertrans->transfn_fcinfo;
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if (pergroup->noTransValue)
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ExecAggInitGroup(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext);
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else if (likely(!pergroup->transValueIsNull))
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ExecAggPlainTransByRef(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext,
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op->d.agg_trans.setno);
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/* cf. select_current_set() */
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aggstate->curaggcontext = op->d.agg_trans.aggcontext;
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aggstate->current_set = op->d.agg_trans.setno;
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EEO_NEXT();
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}
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/* set up aggstate->curpertrans for AggGetAggref() */
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aggstate->curpertrans = pertrans;
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/* see comments above EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL */
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EEO_CASE(EEOP_AGG_PLAIN_TRANS_STRICT_BYREF)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerTrans pertrans = op->d.agg_trans.pertrans;
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AggStatePerGroup pergroup = &aggstate->all_pergroups
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[op->d.agg_trans.setoff]
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[op->d.agg_trans.transno];
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/* invoke transition function in per-tuple context */
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oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
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Assert(!pertrans->transtypeByVal);
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fcinfo->args[0].value = pergroup->transValue;
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fcinfo->args[0].isnull = pergroup->transValueIsNull;
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fcinfo->isnull = false; /* just in case transfn doesn't set it */
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if (likely(!pergroup->transValueIsNull))
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ExecAggPlainTransByRef(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext,
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op->d.agg_trans.setno);
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EEO_NEXT();
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}
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newVal = FunctionCallInvoke(fcinfo);
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/* see comments above EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL */
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EEO_CASE(EEOP_AGG_PLAIN_TRANS_BYREF)
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{
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AggState *aggstate = castNode(AggState, state->parent);
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AggStatePerTrans pertrans = op->d.agg_trans.pertrans;
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AggStatePerGroup pergroup = &aggstate->all_pergroups
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[op->d.agg_trans.setoff]
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[op->d.agg_trans.transno];
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/*
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* For pass-by-ref datatype, must copy the new value into
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* aggcontext and free the prior transValue. But if transfn
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* returned a pointer to its first input, we don't need to do
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* anything. Also, if transfn returned a pointer to a R/W
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* expanded object that is already a child of the aggcontext,
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* assume we can adopt that value without copying it.
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*
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* It's safe to compare newVal with pergroup->transValue without
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* regard for either being NULL, because ExecAggTransReparent()
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* takes care to set transValue to 0 when NULL. Otherwise we could
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* end up accidentally not reparenting, when the transValue has
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* the same numerical value as newValue, despite being NULL. This
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* is a somewhat hot path, making it undesirable to instead solve
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* this with another branch for the common case of the transition
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* function returning its (modified) input argument.
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*/
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if (DatumGetPointer(newVal) != DatumGetPointer(pergroup->transValue))
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newVal = ExecAggTransReparent(aggstate, pertrans,
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newVal, fcinfo->isnull,
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pergroup->transValue,
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pergroup->transValueIsNull);
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Assert(!pertrans->transtypeByVal);
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pergroup->transValue = newVal;
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pergroup->transValueIsNull = fcinfo->isnull;
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MemoryContextSwitchTo(oldContext);
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ExecAggPlainTransByRef(aggstate, pertrans, pergroup,
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op->d.agg_trans.aggcontext,
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op->d.agg_trans.setno);
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EEO_NEXT();
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}
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@ -4145,7 +4126,8 @@ ExecEvalSysVar(ExprState *state, ExprEvalStep *op, ExprContext *econtext,
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* value for a group. We use it as the initial value for transValue.
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*/
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void
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ExecAggInitGroup(AggState *aggstate, AggStatePerTrans pertrans, AggStatePerGroup pergroup)
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ExecAggInitGroup(AggState *aggstate, AggStatePerTrans pertrans, AggStatePerGroup pergroup,
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ExprContext *aggcontext)
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{
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FunctionCallInfo fcinfo = pertrans->transfn_fcinfo;
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MemoryContext oldContext;
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@ -4156,7 +4138,7 @@ ExecAggInitGroup(AggState *aggstate, AggStatePerTrans pertrans, AggStatePerGroup
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* that the agg's input type is binary-compatible with its transtype, so
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* straight copy here is OK.)
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*/
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oldContext = MemoryContextSwitchTo(aggstate->curaggcontext->ecxt_per_tuple_memory);
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oldContext = MemoryContextSwitchTo(aggcontext->ecxt_per_tuple_memory);
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pergroup->transValue = datumCopy(fcinfo->args[1].value,
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pertrans->transtypeByVal,
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pertrans->transtypeLen);
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@ -4243,3 +4225,90 @@ ExecEvalAggOrderedTransTuple(ExprState *state, ExprEvalStep *op,
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ExecStoreVirtualTuple(pertrans->sortslot);
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tuplesort_puttupleslot(pertrans->sortstates[setno], pertrans->sortslot);
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}
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/* implementation of transition function invocation for byval types */
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static pg_attribute_always_inline void
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ExecAggPlainTransByVal(AggState *aggstate, AggStatePerTrans pertrans,
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AggStatePerGroup pergroup,
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ExprContext *aggcontext, int setno)
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{
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FunctionCallInfo fcinfo = pertrans->transfn_fcinfo;
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MemoryContext oldContext;
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Datum newVal;
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/* cf. select_current_set() */
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aggstate->curaggcontext = aggcontext;
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aggstate->current_set = setno;
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/* set up aggstate->curpertrans for AggGetAggref() */
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aggstate->curpertrans = pertrans;
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/* invoke transition function in per-tuple context */
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oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
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fcinfo->args[0].value = pergroup->transValue;
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fcinfo->args[0].isnull = pergroup->transValueIsNull;
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fcinfo->isnull = false; /* just in case transfn doesn't set it */
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newVal = FunctionCallInvoke(fcinfo);
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pergroup->transValue = newVal;
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pergroup->transValueIsNull = fcinfo->isnull;
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MemoryContextSwitchTo(oldContext);
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}
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/* implementation of transition function invocation for byref types */
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static pg_attribute_always_inline void
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ExecAggPlainTransByRef(AggState *aggstate, AggStatePerTrans pertrans,
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AggStatePerGroup pergroup,
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ExprContext *aggcontext, int setno)
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{
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FunctionCallInfo fcinfo = pertrans->transfn_fcinfo;
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MemoryContext oldContext;
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Datum newVal;
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/* cf. select_current_set() */
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aggstate->curaggcontext = aggcontext;
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aggstate->current_set = setno;
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/* set up aggstate->curpertrans for AggGetAggref() */
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aggstate->curpertrans = pertrans;
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/* invoke transition function in per-tuple context */
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oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
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fcinfo->args[0].value = pergroup->transValue;
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fcinfo->args[0].isnull = pergroup->transValueIsNull;
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fcinfo->isnull = false; /* just in case transfn doesn't set it */
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newVal = FunctionCallInvoke(fcinfo);
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/*
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* For pass-by-ref datatype, must copy the new value into
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* aggcontext and free the prior transValue. But if transfn
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* returned a pointer to its first input, we don't need to do
|
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* anything. Also, if transfn returned a pointer to a R/W
|
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* expanded object that is already a child of the aggcontext,
|
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* assume we can adopt that value without copying it.
|
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*
|
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* It's safe to compare newVal with pergroup->transValue without
|
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* regard for either being NULL, because ExecAggTransReparent()
|
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* takes care to set transValue to 0 when NULL. Otherwise we could
|
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* end up accidentally not reparenting, when the transValue has
|
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* the same numerical value as newValue, despite being NULL. This
|
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* is a somewhat hot path, making it undesirable to instead solve
|
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* this with another branch for the common case of the transition
|
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* function returning its (modified) input argument.
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*/
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if (DatumGetPointer(newVal) != DatumGetPointer(pergroup->transValue))
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newVal = ExecAggTransReparent(aggstate, pertrans,
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newVal, fcinfo->isnull,
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pergroup->transValue,
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pergroup->transValueIsNull);
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pergroup->transValue = newVal;
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pergroup->transValueIsNull = fcinfo->isnull;
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|
||||
MemoryContextSwitchTo(oldContext);
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user