postgres/src/backend/catalog/pg_aggregate.c

/*-------------------------------------------------------------------------
 *
 * pg_aggregate.c
 *	  routines to support manipulation of the pg_aggregate relation
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/catalog/pg_aggregate.c,v 1.69 2004/12/31 21:59:38 pgsql Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_language.h"
#include "catalog/pg_proc.h"
#include "optimizer/cost.h"
#include "parser/parse_coerce.h"
#include "parser/parse_func.h"
#include "utils/builtins.h"
#include "utils/syscache.h"


static Oid lookup_agg_function(List *fnName, int nargs, Oid *input_types,
					Oid *rettype);


/*
 * AggregateCreate
 */
void
AggregateCreate(const char *aggName,
				Oid aggNamespace,
				List *aggtransfnName,
				List *aggfinalfnName,
				Oid aggBaseType,
				Oid aggTransType,
				const char *agginitval)
{
	Relation	aggdesc;
	HeapTuple	tup;
	char		nulls[Natts_pg_aggregate];
	Datum		values[Natts_pg_aggregate];
	Form_pg_proc proc;
	Oid			transfn;
	Oid			finalfn = InvalidOid;	/* can be omitted */
	Oid			rettype;
	Oid			finaltype;
	Oid			fnArgs[FUNC_MAX_ARGS];
	int			nargs_transfn;
	Oid			procOid;
	TupleDesc	tupDesc;
	int			i;
	ObjectAddress myself,
				referenced;

	/* sanity checks (caller should have caught these) */
	if (!aggName)
		elog(ERROR, "no aggregate name supplied");

	if (!aggtransfnName)
		elog(ERROR, "aggregate must have a transition function");

	/*
	 * If transtype is polymorphic, basetype must be polymorphic also;
	 * else we will have no way to deduce the actual transtype.
	 */
	if ((aggTransType == ANYARRAYOID || aggTransType == ANYELEMENTOID) &&
		!(aggBaseType == ANYARRAYOID || aggBaseType == ANYELEMENTOID))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
				 errmsg("cannot determine transition data type"),
		errdetail("An aggregate using \"anyarray\" or \"anyelement\" as "
			"transition type must have one of them as its base type.")));

	/* handle transfn */
	MemSet(fnArgs, 0, FUNC_MAX_ARGS * sizeof(Oid));
	fnArgs[0] = aggTransType;
	if (aggBaseType == ANYOID)
		nargs_transfn = 1;
	else
	{
		fnArgs[1] = aggBaseType;
		nargs_transfn = 2;
	}
	transfn = lookup_agg_function(aggtransfnName, nargs_transfn, fnArgs,
								  &rettype);

	/*
	 * Return type of transfn (possibly after refinement by
	 * enforce_generic_type_consistency, if transtype isn't polymorphic)
	 * must exactly match declared transtype.
	 *
	 * In the non-polymorphic-transtype case, it might be okay to allow a
	 * rettype that's binary-coercible to transtype, but I'm not quite
	 * convinced that it's either safe or useful.  When transtype is
	 * polymorphic we *must* demand exact equality.
	 */
	if (rettype != aggTransType)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("return type of transition function %s is not %s",
						NameListToString(aggtransfnName),
						format_type_be(aggTransType))));

	tup = SearchSysCache(PROCOID,
						 ObjectIdGetDatum(transfn),
						 0, 0, 0);
	if (!HeapTupleIsValid(tup))
		elog(ERROR, "cache lookup failed for function %u", transfn);
	proc = (Form_pg_proc) GETSTRUCT(tup);

	/*
	 * If the transfn is strict and the initval is NULL, make sure input
	 * type and transtype are the same (or at least binary-compatible), so
	 * that it's OK to use the first input value as the initial
	 * transValue.
	 */
	if (proc->proisstrict && agginitval == NULL)
	{
		if (!IsBinaryCoercible(aggBaseType, aggTransType))
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
					 errmsg("must not omit initial value when transition function is strict and transition type is not compatible with input type")));
	}
	ReleaseSysCache(tup);

	/* handle finalfn, if supplied */
	if (aggfinalfnName)
	{
		MemSet(fnArgs, 0, FUNC_MAX_ARGS * sizeof(Oid));
		fnArgs[0] = aggTransType;
		finalfn = lookup_agg_function(aggfinalfnName, 1, fnArgs,
									  &finaltype);
	}
	else
	{
		/*
		 * If no finalfn, aggregate result type is type of the state value
		 */
		finaltype = aggTransType;
	}
	Assert(OidIsValid(finaltype));

	/*
	 * If finaltype (i.e. aggregate return type) is polymorphic, basetype
	 * must be polymorphic also, else parser will fail to deduce result
	 * type.  (Note: given the previous test on transtype and basetype,
	 * this cannot happen, unless someone has snuck a finalfn definition
	 * into the catalogs that itself violates the rule against polymorphic
	 * result with no polymorphic input.)
	 */
	if ((finaltype == ANYARRAYOID || finaltype == ANYELEMENTOID) &&
		!(aggBaseType == ANYARRAYOID || aggBaseType == ANYELEMENTOID))
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("cannot determine result data type"),
		errdetail("An aggregate returning \"anyarray\" or \"anyelement\" "
				  "must have one of them as its base type.")));

	/*
	 * Everything looks okay.  Try to create the pg_proc entry for the
	 * aggregate.  (This could fail if there's already a conflicting
	 * entry.)
	 */
	MemSet(fnArgs, 0, FUNC_MAX_ARGS * sizeof(Oid));
	fnArgs[0] = aggBaseType;

	procOid = ProcedureCreate(aggName,
							  aggNamespace,
							  false,	/* no replacement */
							  false,	/* doesn't return a set */
							  finaltype,		/* returnType */
							  INTERNALlanguageId,		/* languageObjectId */
							  0,
							  "aggregate_dummy",		/* placeholder proc */
							  "-",		/* probin */
							  true,		/* isAgg */
							  false,	/* security invoker (currently not
										 * definable for agg) */
							  false,	/* isStrict (not needed for agg) */
							  PROVOLATILE_IMMUTABLE,	/* volatility (not
														 * needed for agg) */
							  1,	/* parameterCount */
							  fnArgs,	/* parameterTypes */
							  NULL);	/* parameterNames */

	/*
	 * Okay to create the pg_aggregate entry.
	 */

	/* initialize nulls and values */
	for (i = 0; i < Natts_pg_aggregate; i++)
	{
		nulls[i] = ' ';
		values[i] = (Datum) NULL;
	}
	values[Anum_pg_aggregate_aggfnoid - 1] = ObjectIdGetDatum(procOid);
	values[Anum_pg_aggregate_aggtransfn - 1] = ObjectIdGetDatum(transfn);
	values[Anum_pg_aggregate_aggfinalfn - 1] = ObjectIdGetDatum(finalfn);
	values[Anum_pg_aggregate_aggtranstype - 1] = ObjectIdGetDatum(aggTransType);
	if (agginitval)
		values[Anum_pg_aggregate_agginitval - 1] =
			DirectFunctionCall1(textin, CStringGetDatum(agginitval));
	else
		nulls[Anum_pg_aggregate_agginitval - 1] = 'n';

	aggdesc = heap_openr(AggregateRelationName, RowExclusiveLock);
	tupDesc = aggdesc->rd_att;

	tup = heap_formtuple(tupDesc, values, nulls);
	simple_heap_insert(aggdesc, tup);

	CatalogUpdateIndexes(aggdesc, tup);

	heap_close(aggdesc, RowExclusiveLock);

	/*
	 * Create dependencies for the aggregate (above and beyond those
	 * already made by ProcedureCreate).  Note: we don't need an explicit
	 * dependency on aggTransType since we depend on it indirectly through
	 * transfn.
	 */
	myself.classId = RelOid_pg_proc;
	myself.objectId = procOid;
	myself.objectSubId = 0;

	/* Depends on transition function */
	referenced.classId = RelOid_pg_proc;
	referenced.objectId = transfn;
	referenced.objectSubId = 0;
	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

	/* Depends on final function, if any */
	if (OidIsValid(finalfn))
	{
		referenced.classId = RelOid_pg_proc;
		referenced.objectId = finalfn;
		referenced.objectSubId = 0;
		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
	}
}

/*
 * lookup_agg_function -- common code for finding both transfn and finalfn
 */
static Oid
lookup_agg_function(List *fnName,
					int nargs,
					Oid *input_types,
					Oid *rettype)
{
	Oid			fnOid;
	bool		retset;
	Oid		   *true_oid_array;
	FuncDetailCode fdresult;

	/*
	 * func_get_detail looks up the function in the catalogs, does
	 * disambiguation for polymorphic functions, handles inheritance, and
	 * returns the funcid and type and set or singleton status of the
	 * function's return value.  it also returns the true argument types
	 * to the function.
	 */
	fdresult = func_get_detail(fnName, NIL, nargs, input_types,
							   &fnOid, rettype, &retset,
							   &true_oid_array);

	/* only valid case is a normal function not returning a set */
	if (fdresult != FUNCDETAIL_NORMAL || !OidIsValid(fnOid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("function %s does not exist",
					func_signature_string(fnName, nargs, input_types))));
	if (retset)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("function %s returns a set",
					func_signature_string(fnName, nargs, input_types))));

	/*
	 * If the given type(s) are all polymorphic, there's nothing we can
	 * check.  Otherwise, enforce consistency, and possibly refine the
	 * result type.
	 */
	if ((input_types[0] == ANYARRAYOID || input_types[0] == ANYELEMENTOID) &&
		(nargs == 1 ||
	 (input_types[1] == ANYARRAYOID || input_types[1] == ANYELEMENTOID)))
	{
		/* nothing to check here */
	}
	else
	{
		*rettype = enforce_generic_type_consistency(input_types,
													true_oid_array,
													nargs,
													*rettype);
	}

	/*
	 * func_get_detail will find functions requiring run-time argument
	 * type coercion, but nodeAgg.c isn't prepared to deal with that
	 */
	if (true_oid_array[0] != ANYARRAYOID &&
		true_oid_array[0] != ANYELEMENTOID &&
		!IsBinaryCoercible(input_types[0], true_oid_array[0]))
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("function %s requires run-time type coercion",
				 func_signature_string(fnName, nargs, true_oid_array))));

	if (nargs == 2 &&
		true_oid_array[1] != ANYARRAYOID &&
		true_oid_array[1] != ANYELEMENTOID &&
		!IsBinaryCoercible(input_types[1], true_oid_array[1]))
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("function %s requires run-time type coercion",
				 func_signature_string(fnName, nargs, true_oid_array))));

	return fnOid;
}