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Allow polymorphic aggregates to have non-polymorphic state data types.

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Before 9.4, such an aggregate couldn't be declared, because its final
function would have to have polymorphic result type but no polymorphic
argument, which CREATE FUNCTION would quite properly reject.  The
ordered-set-aggregate patch found a workaround: allow the final function
to be declared as accepting additional dummy arguments that have types
matching the aggregate's regular input arguments.  However, we failed
to notice that this problem applies just as much to regular aggregates,
despite the fact that we had a built-in regular aggregate array_agg()
that was known to be undeclarable in SQL because its final function
had an illegal signature.  So what we should have done, and what this
patch does, is to decouple the extra-dummy-arguments behavior from
ordered-set aggregates and make it generally available for all aggregate
declarations.  We have to put this into 9.4 rather than waiting till
later because it slightly alters the rules for declaring ordered-set
aggregates.

The patch turned out a bit bigger than I'd hoped because it proved
necessary to record the extra-arguments option in a new pg_aggregate
column.  I'd thought we could just look at the final function's pronargs
at runtime, but that didn't work well for variadic final functions.
It's probably just as well though, because it simplifies life for pg_dump
to record the option explicitly.

While at it, fix array_agg() to have a valid final-function signature,
and add an opr_sanity test to notice future deviations from polymorphic
consistency.  I also marked the percentile_cont() aggregates as not
needing extra arguments, since they don't.
This commit is contained in:
Tom Lane
2014-04-23 19:17:31 -04:00
parent 125ba2945a
commit f0fedfe82c
17 changed files with 509 additions and 298 deletions
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93
src/backend/catalog/pg_aggregate.c
View File

@@ -60,6 +60,8 @@ AggregateCreate(const char *aggName,
List *aggmtransfnName,
List *aggminvtransfnName,
List *aggmfinalfnName,
bool finalfnExtraArgs,
bool mfinalfnExtraArgs,
List *aggsortopName,
Oid aggTransType,
int32 aggTransSpace,
@@ -344,48 +346,46 @@ AggregateCreate(const char *aggName,
ReleaseSysCache(tup);
}
/*
* Set up fnArgs for looking up finalfn(s)
*
* For ordinary aggs, the finalfn just takes the transtype. For
* ordered-set aggs, it takes the transtype plus all args. (The
* aggregated args are useless at runtime, and are actually passed as
* NULLs, but we may need them in the function signature to allow
* resolution of a polymorphic agg's result type.)
*/
fnArgs[0] = aggTransType;
if (AGGKIND_IS_ORDERED_SET(aggKind))
{
nargs_finalfn = numArgs + 1;
memcpy(fnArgs + 1, aggArgTypes, numArgs * sizeof(Oid));
}
else
{
nargs_finalfn = 1;
/* variadic-ness of the aggregate doesn't affect finalfn */
variadicArgType = InvalidOid;
}
/* handle finalfn, if supplied */
if (aggfinalfnName)
{
/*
* If finalfnExtraArgs is specified, the transfn takes the transtype
* plus all args; otherwise, it just takes the transtype plus any
* direct args. (Non-direct args are useless at runtime, and are
* actually passed as NULLs, but we may need them in the function
* signature to allow resolution of a polymorphic agg's result type.)
*/
Oid ffnVariadicArgType = variadicArgType;
fnArgs[0] = aggTransType;
memcpy(fnArgs + 1, aggArgTypes, numArgs * sizeof(Oid));
if (finalfnExtraArgs)
nargs_finalfn = numArgs + 1;
else
{
nargs_finalfn = numDirectArgs + 1;
if (numDirectArgs < numArgs)
{
/* variadic argument doesn't affect finalfn */
ffnVariadicArgType = InvalidOid;
}
}
finalfn = lookup_agg_function(aggfinalfnName, nargs_finalfn,
fnArgs, variadicArgType,
fnArgs, ffnVariadicArgType,
&finaltype);
/*
* The finalfn of an ordered-set agg will certainly be passed at least
* one null argument, so complain if it's strict. Nothing bad would
* happen at runtime (you'd just get a null result), but it's surely
* not what the user wants, so let's complain now.
*
* Note: it's likely that a strict transfn would also be a mistake,
* but the case isn't quite so airtight, so we let that pass.
* When finalfnExtraArgs is specified, the finalfn will certainly be
* passed at least one null argument, so complain if it's strict.
* Nothing bad would happen at runtime (you'd just get a null result),
* but it's surely not what the user wants, so let's complain now.
*/
if (AGGKIND_IS_ORDERED_SET(aggKind) && func_strict(finalfn))
if (finalfnExtraArgs && func_strict(finalfn))
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("final function of an ordered-set aggregate must not be declared STRICT")));
errmsg("final function with extra arguments must not be declared STRICT")));
}
else
{
@@ -434,21 +434,34 @@ AggregateCreate(const char *aggName,
if (aggmfinalfnName)
{
/*
* The arguments are the same as for the regular finalfn, except
* that the transition data type might be different. So re-use
* the fnArgs values set up above, except for that one.
* The arguments are figured the same way as for the regular
* finalfn, but using aggmTransType and mfinalfnExtraArgs.
*/
Oid ffnVariadicArgType = variadicArgType;
fnArgs[0] = aggmTransType;
memcpy(fnArgs + 1, aggArgTypes, numArgs * sizeof(Oid));
if (mfinalfnExtraArgs)
nargs_finalfn = numArgs + 1;
else
{
nargs_finalfn = numDirectArgs + 1;
if (numDirectArgs < numArgs)
{
/* variadic argument doesn't affect finalfn */
ffnVariadicArgType = InvalidOid;
}
}
mfinalfn = lookup_agg_function(aggmfinalfnName, nargs_finalfn,
fnArgs, variadicArgType,
fnArgs, ffnVariadicArgType,
&rettype);
/* As above, check strictness if it's an ordered-set agg */
if (AGGKIND_IS_ORDERED_SET(aggKind) && func_strict(mfinalfn))
/* As above, check strictness if mfinalfnExtraArgs is given */
if (mfinalfnExtraArgs && func_strict(mfinalfn))
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("final function of an ordered-set aggregate must not be declared STRICT")));
errmsg("final function with extra arguments must not be declared STRICT")));
}
else
{
@@ -554,6 +567,8 @@ AggregateCreate(const char *aggName,
values[Anum_pg_aggregate_aggmtransfn - 1] = ObjectIdGetDatum(mtransfn);
values[Anum_pg_aggregate_aggminvtransfn - 1] = ObjectIdGetDatum(minvtransfn);
values[Anum_pg_aggregate_aggmfinalfn - 1] = ObjectIdGetDatum(mfinalfn);
values[Anum_pg_aggregate_aggfinalextra - 1] = BoolGetDatum(finalfnExtraArgs);
values[Anum_pg_aggregate_aggmfinalextra - 1] = BoolGetDatum(mfinalfnExtraArgs);
values[Anum_pg_aggregate_aggsortop - 1] = ObjectIdGetDatum(sortop);
values[Anum_pg_aggregate_aggtranstype - 1] = ObjectIdGetDatum(aggTransType);
values[Anum_pg_aggregate_aggtransspace - 1] = Int32GetDatum(aggTransSpace);