/*-------------------------------------------------------------------------
 *
 * pg_operator.c
 *	  routines to support manipulation of the pg_operator relation
 *
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /home/postgres/cvs_root/pgsql-r-v7.2/src/backend/catalog/pg_operator.c,v 1.1.1.1 2002/02/07 17:51:41 bpalmer Exp $
 *
 * NOTES
 *	  these routines moved here from commands/define.c and somewhat cleaned up.
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/indexing.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "parser/parse_func.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/syscache.h"


static Oid OperatorGetWithOpenRelation(Relation pg_operator_desc,
							const char *operatorName,
							Oid leftObjectId,
							Oid rightObjectId,
							bool *defined);

static Oid OperatorGet(char *operatorName,
			char *leftTypeName,
			char *rightTypeName,
			bool *defined);

static Oid OperatorShellMake(char *operatorName,
				  char *leftTypeName,
				  char *rightTypeName);

static void OperatorDef(char *operatorName,
			char *leftTypeName,
			char *rightTypeName,
			char *procedureName,
			uint16 precedence,
			bool isLeftAssociative,
			char *commutatorName,
			char *negatorName,
			char *restrictionName,
			char *oinName,
			bool canHash,
			char *leftSortName,
			char *rightSortName);

static void OperatorUpd(Oid baseId, Oid commId, Oid negId);


/*
 * Check whether a proposed operator name is legal
 *
 * This had better match the behavior of parser/scan.l!
 *
 * We need this because the parser is not smart enough to check that
 * the arguments of CREATE OPERATOR's COMMUTATOR, NEGATOR, etc clauses
 * are operator names rather than some other lexical entity.
 */
static bool
validOperatorName(const char *name)
{
	size_t		len = strlen(name);

	/* Can't be empty or too long */
	if (len == 0 || len >= NAMEDATALEN)
		return false;

	/* Can't contain any invalid characters */
	/* Test string here should match op_chars in scan.l */
	if (strspn(name, "~!@#^&|`?$+-*/%<>=") != len)
		return false;

	/* Can't contain slash-star or dash-dash (comment starts) */
	if (strstr(name, "/*") || strstr(name, "--"))
		return false;

	/*
	 * For SQL92 compatibility, '+' and '-' cannot be the last char of a
	 * multi-char operator unless the operator contains chars that are not
	 * in SQL92 operators. The idea is to lex '=-' as two operators, but
	 * not to forbid operator names like '?-' that could not be sequences
	 * of SQL92 operators.
	 */
	if (len > 1 &&
		(name[len - 1] == '+' ||
		 name[len - 1] == '-'))
	{
		int			ic;

		for (ic = len - 2; ic >= 0; ic--)
		{
			if (strchr("~!@#^&|`?$%", name[ic]))
				break;
		}
		if (ic < 0)
			return false;		/* nope, not valid */
	}

	/* != isn't valid either, because parser will convert it to <> */
	if (strcmp(name, "!=") == 0)
		return false;

	return true;
}


/* ----------------------------------------------------------------
 *		OperatorGetWithOpenRelation
 *
 *		performs a scan on pg_operator for an operator tuple
 *		with given name and left/right type oids.
 *
 *	  pg_operator_desc	-- reldesc for pg_operator
 *	  operatorName		-- name of operator to fetch
 *	  leftObjectId		-- left data type oid of operator to fetch
 *	  rightObjectId		-- right data type oid of operator to fetch
 *	  defined			-- set TRUE if defined (not a shell)
 * ----------------------------------------------------------------
 */
static Oid
OperatorGetWithOpenRelation(Relation pg_operator_desc,
							const char *operatorName,
							Oid leftObjectId,
							Oid rightObjectId,
							bool *defined)
{
	HeapScanDesc pg_operator_scan;
	Oid			operatorObjectId;
	HeapTuple	tup;
	ScanKeyData opKey[3];

	/*
	 * form scan key
	 */
	ScanKeyEntryInitialize(&opKey[0], 0x0,
						   Anum_pg_operator_oprname,
						   F_NAMEEQ,
						   PointerGetDatum(operatorName));
	ScanKeyEntryInitialize(&opKey[1], 0x0,
						   Anum_pg_operator_oprleft,
						   F_OIDEQ,
						   ObjectIdGetDatum(leftObjectId));
	ScanKeyEntryInitialize(&opKey[2], 0x0,
						   Anum_pg_operator_oprright,
						   F_OIDEQ,
						   ObjectIdGetDatum(rightObjectId));

	/*
	 * begin the scan
	 */
	pg_operator_scan = heap_beginscan(pg_operator_desc,
									  0,
									  SnapshotSelf,		/* no cache? */
									  3,
									  opKey);

	/*
	 * fetch the operator tuple, if it exists, and determine the proper
	 * return oid value.
	 */
	tup = heap_getnext(pg_operator_scan, 0);

	if (HeapTupleIsValid(tup))
	{
		regproc		oprcode = ((Form_pg_operator) GETSTRUCT(tup))->oprcode;

		operatorObjectId = tup->t_data->t_oid;
		*defined = RegProcedureIsValid(oprcode);
	}
	else
	{
		operatorObjectId = InvalidOid;
		*defined = false;
	}

	/*
	 * close the scan and return the oid.
	 */
	heap_endscan(pg_operator_scan);

	return operatorObjectId;
}

/* ----------------------------------------------------------------
 *		OperatorGet
 *
 *		finds the operator associated with the specified name
 *		and left and right type names.
 * ----------------------------------------------------------------
 */
static Oid
OperatorGet(char *operatorName,
			char *leftTypeName,
			char *rightTypeName,
			bool *defined)
{
	Relation	pg_operator_desc;
	Oid			operatorObjectId;
	Oid			leftObjectId = InvalidOid;
	Oid			rightObjectId = InvalidOid;
	bool		leftDefined = false;
	bool		rightDefined = false;

	/*
	 * look up the operator data types.
	 *
	 * Note: types must be defined before operators
	 */
	if (leftTypeName)
	{
		leftObjectId = TypeGet(leftTypeName, &leftDefined);

		if (!OidIsValid(leftObjectId) || !leftDefined)
			elog(ERROR, "left type \"%s\" of operator %s does not exist",
				 leftTypeName, operatorName);
	}

	if (rightTypeName)
	{
		rightObjectId = TypeGet(rightTypeName, &rightDefined);

		if (!OidIsValid(rightObjectId) || !rightDefined)
			elog(ERROR, "right type \"%s\" of operator %s does not exist",
				 rightTypeName, operatorName);
	}

	if (!((OidIsValid(leftObjectId) && leftDefined) ||
		  (OidIsValid(rightObjectId) && rightDefined)))
		elog(ERROR, "operator %s must have at least one operand type", operatorName);

	/*
	 * open the pg_operator relation
	 */
	pg_operator_desc = heap_openr(OperatorRelationName, AccessShareLock);

	/*
	 * get the oid for the operator with the appropriate name and
	 * left/right types.
	 */
	operatorObjectId = OperatorGetWithOpenRelation(pg_operator_desc,
												   operatorName,
												   leftObjectId,
												   rightObjectId,
												   defined);

	/*
	 * close the relation and return the operator oid.
	 */
	heap_close(pg_operator_desc, AccessShareLock);

	return operatorObjectId;
}

/* ----------------------------------------------------------------
 *		OperatorShellMake
 *
 *		Specify operator name and left and right type names,
 *		fill an operator struct with this info and NULL's,
 *		call heap_insert and return the Oid to the caller.
 * ----------------------------------------------------------------
 */
static Oid
OperatorShellMake(char *operatorName,
				  char *leftTypeName,
				  char *rightTypeName)
{
	Relation	pg_operator_desc;
	Oid			operatorObjectId;
	Oid			leftObjectId = InvalidOid;
	Oid			rightObjectId = InvalidOid;
	bool		leftDefined = false;
	bool		rightDefined = false;
	int			i;
	HeapTuple	tup;
	Datum		values[Natts_pg_operator];
	char		nulls[Natts_pg_operator];
	NameData	oname;
	TupleDesc	tupDesc;

	/*
	 * validate operator name
	 */
	if (!validOperatorName(operatorName))
		elog(ERROR, "\"%s\" is not a valid operator name", operatorName);

	/*
	 * get the left and right type oid's for this operator
	 */
	if (leftTypeName)
		leftObjectId = TypeGet(leftTypeName, &leftDefined);

	if (rightTypeName)
		rightObjectId = TypeGet(rightTypeName, &rightDefined);

	if (!((OidIsValid(leftObjectId) && leftDefined) ||
		  (OidIsValid(rightObjectId) && rightDefined)))
		elog(ERROR, "OperatorShellMake: the operand types are not valid");

	/*
	 * open pg_operator
	 */
	pg_operator_desc = heap_openr(OperatorRelationName, RowExclusiveLock);

	/*
	 * initialize our *nulls and *values arrays
	 */
	for (i = 0; i < Natts_pg_operator; ++i)
	{
		nulls[i] = ' ';
		values[i] = (Datum) NULL;		/* redundant, but safe */
	}

	/*
	 * initialize values[] with the operator name and input data types.
	 * Note that oprcode is set to InvalidOid, indicating it's a shell.
	 */
	i = 0;
	namestrcpy(&oname, operatorName);
	values[i++] = NameGetDatum(&oname);
	values[i++] = Int32GetDatum(GetUserId());
	values[i++] = UInt16GetDatum(0);
	values[i++] = CharGetDatum('b');	/* assume it's binary */
	values[i++] = BoolGetDatum(false);
	values[i++] = BoolGetDatum(false);
	values[i++] = ObjectIdGetDatum(leftObjectId);		/* <-- left oid */
	values[i++] = ObjectIdGetDatum(rightObjectId);		/* <-- right oid */
	values[i++] = ObjectIdGetDatum(InvalidOid);
	values[i++] = ObjectIdGetDatum(InvalidOid);
	values[i++] = ObjectIdGetDatum(InvalidOid);
	values[i++] = ObjectIdGetDatum(InvalidOid);
	values[i++] = ObjectIdGetDatum(InvalidOid);
	values[i++] = ObjectIdGetDatum(InvalidOid);
	values[i++] = ObjectIdGetDatum(InvalidOid);
	values[i++] = ObjectIdGetDatum(InvalidOid);

	/*
	 * create a new operator tuple
	 */
	tupDesc = pg_operator_desc->rd_att;

	tup = heap_formtuple(tupDesc, values, nulls);

	/*
	 * insert our "shell" operator tuple
	 */
	heap_insert(pg_operator_desc, tup);
	operatorObjectId = tup->t_data->t_oid;

	if (RelationGetForm(pg_operator_desc)->relhasindex)
	{
		Relation	idescs[Num_pg_operator_indices];

		CatalogOpenIndices(Num_pg_operator_indices, Name_pg_operator_indices, idescs);
		CatalogIndexInsert(idescs, Num_pg_operator_indices, pg_operator_desc, tup);
		CatalogCloseIndices(Num_pg_operator_indices, idescs);
	}

	heap_freetuple(tup);

	/*
	 * close the operator relation and return the oid.
	 */
	heap_close(pg_operator_desc, RowExclusiveLock);

	return operatorObjectId;
}

/* --------------------------------
 * OperatorDef
 *
 * This routine gets complicated because it allows the user to
 * specify operators that do not exist.  For example, if operator
 * "op" is being defined, the negator operator "negop" and the
 * commutator "commop" can also be defined without specifying
 * any information other than their names.	Since in order to
 * add "op" to the PG_OPERATOR catalog, all the Oid's for these
 * operators must be placed in the fields of "op", a forward
 * declaration is done on the commutator and negator operators.
 * This is called creating a shell, and its main effect is to
 * create a tuple in the PG_OPERATOR catalog with minimal
 * information about the operator (just its name and types).
 * Forward declaration is used only for this purpose, it is
 * not available to the user as it is for type definition.
 *
 * Algorithm:
 *
 * check if operator already defined
 *	  if so, but oprcode is null, save the Oid -- we are filling in a shell
 *	  otherwise error
 * get the attribute types from relation descriptor for pg_operator
 * assign values to the fields of the operator:
 *	 operatorName
 *	 owner id (simply the user id of the caller)
 *	 precedence
 *	 operator "kind" either "b" for binary or "l" for left unary
 *	 isLeftAssociative boolean
 *	 canHash boolean
 *	 leftTypeObjectId -- type must already be defined
 *	 rightTypeObjectId -- this is optional, enter ObjectId=0 if none specified
 *	 resultType -- defer this, since it must be determined from
 *				   the pg_procedure catalog
 *	 commutatorObjectId -- if this is NULL, enter ObjectId=0
 *					  else if this already exists, enter its ObjectId
 *					  else if this does not yet exist, and is not
 *						the same as the main operatorName, then create
 *						a shell and enter the new ObjectId
 *					  else if this does not exist but IS the same
 *						name & types as the main operator, set the ObjectId=0.
 *						(We are creating a self-commutating operator.)
 *						The link will be fixed later by OperatorUpd.
 *	 negatorObjectId   -- same as for commutatorObjectId
 *	 leftSortObjectId  -- same as for commutatorObjectId
 *	 rightSortObjectId -- same as for commutatorObjectId
 *	 operatorProcedure -- must access the pg_procedure catalog to get the
 *				   ObjectId of the procedure that actually does the operator
 *				   actions this is required.  Do a lookup to find out the
 *				   return type of the procedure
 *	 restrictionProcedure -- must access the pg_procedure catalog to get
 *				   the ObjectId but this is optional
 *	 joinProcedure -- same as restrictionProcedure
 * now either insert or replace the operator into the pg_operator catalog
 * if the operator shell is being filled in
 *	 access the catalog in order to get a valid buffer
 *	 create a tuple using ModifyHeapTuple
 *	 get the t_self from the modified tuple and call RelationReplaceHeapTuple
 * else if a new operator is being created
 *	 create a tuple using heap_formtuple
 *	 call heap_insert
 * --------------------------------
 *		"X" indicates an optional argument (i.e. one that can be NULL)
 *		operatorName;			-- operator name
 *		leftTypeName;			-- X left type name
 *		rightTypeName;			-- X right type name
 *		procedureName;			-- procedure name for operator code
 *		precedence;				-- operator precedence
 *		isLeftAssociative;		-- operator is left associative?
 *		commutatorName;			-- X commutator operator name
 *		negatorName;			-- X negator operator name
 *		restrictionName;		-- X restriction sel. procedure name
 *		joinName;				-- X join sel. procedure name
 *		canHash;				-- can hash join be used with operator?
 *		leftSortName;			-- X left sort operator (for merge join)
 *		rightSortName;			-- X right sort operator (for merge join)
 */
static void
OperatorDef(char *operatorName,
			char *leftTypeName,
			char *rightTypeName,
			char *procedureName,
			uint16 precedence,
			bool isLeftAssociative,
			char *commutatorName,
			char *negatorName,
			char *restrictionName,
			char *joinName,
			bool canHash,
			char *leftSortName,
			char *rightSortName)
{
	int			i,
				j;
	Relation	pg_operator_desc;
	HeapScanDesc pg_operator_scan;
	HeapTuple	tup;
	char		nulls[Natts_pg_operator];
	char		replaces[Natts_pg_operator];
	Datum		values[Natts_pg_operator];
	Oid			operatorObjectId;
	bool		operatorAlreadyDefined;
	Oid			leftTypeId = InvalidOid;
	Oid			rightTypeId = InvalidOid;
	Oid			commutatorId = InvalidOid;
	Oid			negatorId = InvalidOid;
	bool		leftDefined = false;
	bool		rightDefined = false;
	bool		selfCommutator = false;
	char	   *name[4];
	Oid			typeId[FUNC_MAX_ARGS];
	int			nargs;
	NameData	oname;
	TupleDesc	tupDesc;
	ScanKeyData opKey[3];

	operatorObjectId = OperatorGet(operatorName,
								   leftTypeName,
								   rightTypeName,
								   &operatorAlreadyDefined);

	if (operatorAlreadyDefined)
		elog(ERROR, "OperatorDef: operator \"%s\" already defined",
			 operatorName);

	/*
	 * At this point, if operatorObjectId is not InvalidOid then we are
	 * filling in a previously-created shell.
	 */

	/*
	 * validate operator name
	 */
	if (!validOperatorName(operatorName))
		elog(ERROR, "\"%s\" is not a valid operator name", operatorName);

	/*
	 * look up the operator data types.
	 *
	 * Note: types must be defined before operators
	 */
	if (leftTypeName)
	{
		leftTypeId = TypeGet(leftTypeName, &leftDefined);

		if (!OidIsValid(leftTypeId) || !leftDefined)
			elog(ERROR, "left type \"%s\" does not exist",
				 leftTypeName);
	}

	if (rightTypeName)
	{
		rightTypeId = TypeGet(rightTypeName, &rightDefined);

		if (!OidIsValid(rightTypeId) || !rightDefined)
			elog(ERROR, "right type \"%s\" does not exist",
				 rightTypeName);
	}

	if (!((OidIsValid(leftTypeId) && leftDefined) ||
		  (OidIsValid(rightTypeId) && rightDefined)))
		elog(ERROR, "operator must have at least one operand type");

	for (i = 0; i < Natts_pg_operator; ++i)
	{
		values[i] = (Datum) NULL;
		replaces[i] = 'r';
		nulls[i] = ' ';
	}

	/*
	 * Look up registered procedures -- find the return type of
	 * procedureName to place in "result" field. Do this before shells are
	 * created so we don't have to worry about deleting them later.
	 */
	MemSet(typeId, 0, FUNC_MAX_ARGS * sizeof(Oid));
	if (!leftTypeName)
	{
		typeId[0] = rightTypeId;
		nargs = 1;
	}
	else if (!rightTypeName)
	{
		typeId[0] = leftTypeId;
		nargs = 1;
	}
	else
	{
		typeId[0] = leftTypeId;
		typeId[1] = rightTypeId;
		nargs = 2;
	}
	tup = SearchSysCache(PROCNAME,
						 PointerGetDatum(procedureName),
						 Int32GetDatum(nargs),
						 PointerGetDatum(typeId),
						 0);
	if (!HeapTupleIsValid(tup))
		func_error("OperatorDef", procedureName, nargs, typeId, NULL);

	values[Anum_pg_operator_oprcode - 1] = ObjectIdGetDatum(tup->t_data->t_oid);
	values[Anum_pg_operator_oprresult - 1] = ObjectIdGetDatum(((Form_pg_proc)
											GETSTRUCT(tup))->prorettype);

	ReleaseSysCache(tup);

	/*
	 * find restriction estimator
	 */
	if (restrictionName)
	{							/* optional */
		Oid			restOid;

		MemSet(typeId, 0, FUNC_MAX_ARGS * sizeof(Oid));
		typeId[0] = 0;			/* Query (opaque type) */
		typeId[1] = OIDOID;		/* operator OID */
		typeId[2] = 0;			/* args list (opaque type) */
		typeId[3] = INT4OID;	/* varRelid */

		restOid = GetSysCacheOid(PROCNAME,
								 PointerGetDatum(restrictionName),
								 Int32GetDatum(4),
								 PointerGetDatum(typeId),
								 0);
		if (!OidIsValid(restOid))
			func_error("OperatorDef", restrictionName, 4, typeId, NULL);

		values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(restOid);
	}
	else
		values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(InvalidOid);

	/*
	 * find join estimator
	 */
	if (joinName)
	{							/* optional */
		Oid			joinOid;

		MemSet(typeId, 0, FUNC_MAX_ARGS * sizeof(Oid));
		typeId[0] = 0;			/* Query (opaque type) */
		typeId[1] = OIDOID;		/* operator OID */
		typeId[2] = 0;			/* args list (opaque type) */

		joinOid = GetSysCacheOid(PROCNAME,
								 PointerGetDatum(joinName),
								 Int32GetDatum(3),
								 PointerGetDatum(typeId),
								 0);
		if (!OidIsValid(joinOid))
			func_error("OperatorDef", joinName, 3, typeId, NULL);

		values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(joinOid);
	}
	else
		values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(InvalidOid);

	/*
	 * set up values in the operator tuple
	 */
	i = 0;
	namestrcpy(&oname, operatorName);
	values[i++] = NameGetDatum(&oname);
	values[i++] = Int32GetDatum(GetUserId());
	values[i++] = UInt16GetDatum(precedence);
	values[i++] = CharGetDatum(leftTypeName ? (rightTypeName ? 'b' : 'r') : 'l');
	values[i++] = BoolGetDatum(isLeftAssociative);
	values[i++] = BoolGetDatum(canHash);
	values[i++] = ObjectIdGetDatum(leftTypeId);
	values[i++] = ObjectIdGetDatum(rightTypeId);

	++i;						/* Skip "oprresult", it was filled in
								 * above */

	/*
	 * Set up the other operators.	If they do not currently exist, create
	 * shells in order to get ObjectId's.
	 */
	name[0] = commutatorName;
	name[1] = negatorName;
	name[2] = leftSortName;
	name[3] = rightSortName;

	for (j = 0; j < 4; ++j)
	{
		if (name[j])
		{
			char	   *otherLeftTypeName = NULL;
			char	   *otherRightTypeName = NULL;
			Oid			otherLeftTypeId = InvalidOid;
			Oid			otherRightTypeId = InvalidOid;
			Oid			other_oid = InvalidOid;
			bool		otherDefined = false;

			switch (j)
			{
				case 0: /* commutator has reversed arg types */
					otherLeftTypeName = rightTypeName;
					otherRightTypeName = leftTypeName;
					otherLeftTypeId = rightTypeId;
					otherRightTypeId = leftTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					commutatorId = other_oid;
					break;
				case 1: /* negator has same arg types */
					otherLeftTypeName = leftTypeName;
					otherRightTypeName = rightTypeName;
					otherLeftTypeId = leftTypeId;
					otherRightTypeId = rightTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					negatorId = other_oid;
					break;
				case 2: /* left sort op takes left-side data type */
					otherLeftTypeName = leftTypeName;
					otherRightTypeName = leftTypeName;
					otherLeftTypeId = leftTypeId;
					otherRightTypeId = leftTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					break;
				case 3: /* right sort op takes right-side data
								 * type */
					otherLeftTypeName = rightTypeName;
					otherRightTypeName = rightTypeName;
					otherLeftTypeId = rightTypeId;
					otherRightTypeId = rightTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					break;
			}

			if (OidIsValid(other_oid))
			{
				/* other op already in catalogs */
				values[i++] = ObjectIdGetDatum(other_oid);
			}
			else if (strcmp(operatorName, name[j]) != 0 ||
					 otherLeftTypeId != leftTypeId ||
					 otherRightTypeId != rightTypeId)
			{
				/* not in catalogs, different from operator */
				other_oid = OperatorShellMake(name[j],
											  otherLeftTypeName,
											  otherRightTypeName);
				if (!OidIsValid(other_oid))
					elog(ERROR,
					   "OperatorDef: can't create operator shell \"%s\"",
						 name[j]);
				values[i++] = ObjectIdGetDatum(other_oid);
			}
			else
			{
				/*
				 * self-linkage to this operator; will fix below. Note
				 * that only self-linkage for commutation makes sense.
				 */
				if (j != 0)
					elog(ERROR,
						 "operator cannot be its own negator or sort operator");
				selfCommutator = true;
				values[i++] = ObjectIdGetDatum(InvalidOid);
			}
		}
		else
		{
			/* other operator is omitted */
			values[i++] = ObjectIdGetDatum(InvalidOid);
		}
	}

	/* last three fields were filled in above */

	pg_operator_desc = heap_openr(OperatorRelationName, RowExclusiveLock);

	/*
	 * If we are adding to an operator shell, get its t_self
	 */
	if (operatorObjectId)
	{
		/* Make sure we can see the shell even if it is new in current cmd */
		CommandCounterIncrement();

		ScanKeyEntryInitialize(&opKey[0], 0x0,
							   Anum_pg_operator_oprname,
							   F_NAMEEQ,
							   PointerGetDatum(operatorName));
		ScanKeyEntryInitialize(&opKey[1], 0x0,
							   Anum_pg_operator_oprleft,
							   F_OIDEQ,
							   ObjectIdGetDatum(leftTypeId));
		ScanKeyEntryInitialize(&opKey[2], 0x0,
							   Anum_pg_operator_oprright,
							   F_OIDEQ,
							   ObjectIdGetDatum(rightTypeId));

		pg_operator_scan = heap_beginscan(pg_operator_desc,
										  0,
										  SnapshotSelf, /* no cache? */
										  3,
										  opKey);

		tup = heap_getnext(pg_operator_scan, 0);
		if (HeapTupleIsValid(tup))
		{
			tup = heap_modifytuple(tup,
								   pg_operator_desc,
								   values,
								   nulls,
								   replaces);

			simple_heap_update(pg_operator_desc, &tup->t_self, tup);
		}
		else
			elog(ERROR, "OperatorDef: operator %u not found", operatorObjectId);

		heap_endscan(pg_operator_scan);
	}
	else
	{
		tupDesc = pg_operator_desc->rd_att;
		tup = heap_formtuple(tupDesc, values, nulls);

		heap_insert(pg_operator_desc, tup);
		operatorObjectId = tup->t_data->t_oid;
	}

	if (RelationGetForm(pg_operator_desc)->relhasindex)
	{
		Relation	idescs[Num_pg_operator_indices];

		CatalogOpenIndices(Num_pg_operator_indices, Name_pg_operator_indices, idescs);
		CatalogIndexInsert(idescs, Num_pg_operator_indices, pg_operator_desc, tup);
		CatalogCloseIndices(Num_pg_operator_indices, idescs);
	}

	heap_close(pg_operator_desc, RowExclusiveLock);

	/*
	 * If a commutator and/or negator link is provided, update the other
	 * operator(s) to point at this one, if they don't already have a
	 * link. This supports an alternate style of operator definition
	 * wherein the user first defines one operator without giving negator
	 * or commutator, then defines the other operator of the pair with the
	 * proper commutator or negator attribute.	That style doesn't require
	 * creation of a shell, and it's the only style that worked right
	 * before Postgres version 6.5. This code also takes care of the
	 * situation where the new operator is its own commutator.
	 */
	if (selfCommutator)
		commutatorId = operatorObjectId;

	if (OidIsValid(commutatorId) || OidIsValid(negatorId))
		OperatorUpd(operatorObjectId, commutatorId, negatorId);
}

/* ----------------------------------------------------------------
 * OperatorUpd
 *
 *	For a given operator, look up its negator and commutator operators.
 *	If they are defined, but their negator and commutator fields
 *	(respectively) are empty, then use the new operator for neg or comm.
 *	This solves a problem for users who need to insert two new operators
 *	which are the negator or commutator of each other.
 * ----------------------------------------------------------------
 */
static void
OperatorUpd(Oid baseId, Oid commId, Oid negId)
{
	int			i;
	Relation	pg_operator_desc;
	HeapScanDesc pg_operator_scan;
	HeapTuple	tup;
	char		nulls[Natts_pg_operator];
	char		replaces[Natts_pg_operator];
	Datum		values[Natts_pg_operator];
	ScanKeyData opKey[1];

	for (i = 0; i < Natts_pg_operator; ++i)
	{
		values[i] = (Datum) 0;
		replaces[i] = ' ';
		nulls[i] = ' ';
	}

	pg_operator_desc = heap_openr(OperatorRelationName, RowExclusiveLock);

	/*
	 * check and update the commutator & negator, if necessary
	 *
	 * First make sure we can see them...
	 */
	CommandCounterIncrement();

	ScanKeyEntryInitialize(&opKey[0], 0x0,
						   ObjectIdAttributeNumber,
						   F_OIDEQ,
						   ObjectIdGetDatum(commId));

	pg_operator_scan = heap_beginscan(pg_operator_desc,
									  0,
									  SnapshotSelf,		/* no cache? */
									  1,
									  opKey);

	tup = heap_getnext(pg_operator_scan, 0);

	/*
	 * if the commutator and negator are the same operator, do one update.
	 * XXX this is probably useless code --- I doubt it ever makes sense
	 * for commutator and negator to be the same thing...
	 */
	if (commId == negId)
	{
		if (HeapTupleIsValid(tup))
		{
			Form_pg_operator t;

			t = (Form_pg_operator) GETSTRUCT(tup);
			if (!OidIsValid(t->oprcom)
				|| !OidIsValid(t->oprnegate))
			{

				if (!OidIsValid(t->oprnegate))
				{
					values[Anum_pg_operator_oprnegate - 1] = ObjectIdGetDatum(baseId);
					replaces[Anum_pg_operator_oprnegate - 1] = 'r';
				}

				if (!OidIsValid(t->oprcom))
				{
					values[Anum_pg_operator_oprcom - 1] = ObjectIdGetDatum(baseId);
					replaces[Anum_pg_operator_oprcom - 1] = 'r';
				}

				tup = heap_modifytuple(tup,
									   pg_operator_desc,
									   values,
									   nulls,
									   replaces);

				simple_heap_update(pg_operator_desc, &tup->t_self, tup);

				if (RelationGetForm(pg_operator_desc)->relhasindex)
				{
					Relation	idescs[Num_pg_operator_indices];

					CatalogOpenIndices(Num_pg_operator_indices, Name_pg_operator_indices, idescs);
					CatalogIndexInsert(idescs, Num_pg_operator_indices, pg_operator_desc, tup);
					CatalogCloseIndices(Num_pg_operator_indices, idescs);
				}
			}
		}
		heap_endscan(pg_operator_scan);

		heap_close(pg_operator_desc, RowExclusiveLock);

		return;
	}

	/* if commutator and negator are different, do two updates */

	if (HeapTupleIsValid(tup) &&
		!(OidIsValid(((Form_pg_operator) GETSTRUCT(tup))->oprcom)))
	{
		values[Anum_pg_operator_oprcom - 1] = ObjectIdGetDatum(baseId);
		replaces[Anum_pg_operator_oprcom - 1] = 'r';
		tup = heap_modifytuple(tup,
							   pg_operator_desc,
							   values,
							   nulls,
							   replaces);

		simple_heap_update(pg_operator_desc, &tup->t_self, tup);

		if (RelationGetForm(pg_operator_desc)->relhasindex)
		{
			Relation	idescs[Num_pg_operator_indices];

			CatalogOpenIndices(Num_pg_operator_indices, Name_pg_operator_indices, idescs);
			CatalogIndexInsert(idescs, Num_pg_operator_indices, pg_operator_desc, tup);
			CatalogCloseIndices(Num_pg_operator_indices, idescs);
		}

		values[Anum_pg_operator_oprcom - 1] = (Datum) NULL;
		replaces[Anum_pg_operator_oprcom - 1] = ' ';
	}

	heap_endscan(pg_operator_scan);

	/* check and update the negator, if necessary */
	opKey[0].sk_argument = ObjectIdGetDatum(negId);

	pg_operator_scan = heap_beginscan(pg_operator_desc,
									  0,
									  SnapshotSelf,		/* no cache? */
									  1,
									  opKey);

	tup = heap_getnext(pg_operator_scan, 0);
	if (HeapTupleIsValid(tup) &&
		!(OidIsValid(((Form_pg_operator) GETSTRUCT(tup))->oprnegate)))
	{
		values[Anum_pg_operator_oprnegate - 1] = ObjectIdGetDatum(baseId);
		replaces[Anum_pg_operator_oprnegate - 1] = 'r';
		tup = heap_modifytuple(tup,
							   pg_operator_desc,
							   values,
							   nulls,
							   replaces);

		simple_heap_update(pg_operator_desc, &tup->t_self, tup);

		if (RelationGetForm(pg_operator_desc)->relhasindex)
		{
			Relation	idescs[Num_pg_operator_indices];

			CatalogOpenIndices(Num_pg_operator_indices, Name_pg_operator_indices, idescs);
			CatalogIndexInsert(idescs, Num_pg_operator_indices, pg_operator_desc, tup);
			CatalogCloseIndices(Num_pg_operator_indices, idescs);
		}
	}

	heap_endscan(pg_operator_scan);

	heap_close(pg_operator_desc, RowExclusiveLock);
}


/* ----------------------------------------------------------------
 * OperatorCreate
 *
 * This is now just an interface procedure for OperatorDef ...
 *
 * "X" indicates an optional argument (i.e. one that can be NULL)
 *		operatorName;			-- operator name
 *		leftTypeName;			-- X left type name
 *		rightTypeName;			-- X right type name
 *		procedureName;			-- procedure for operator
 *		precedence;				-- operator precedence
 *		isLeftAssociative;		-- operator is left associative
 *		commutatorName;			-- X commutator operator name
 *		negatorName;			-- X negator operator name
 *		restrictionName;		-- X restriction sel. procedure
 *		joinName;				-- X join sel. procedure
 *		canHash;				-- hash join can be used with this operator
 *		leftSortName;			-- X left sort operator (for merge join)
 *		rightSortName;			-- X right sort operator (for merge join)
 */
void
OperatorCreate(char *operatorName,
			   char *leftTypeName,
			   char *rightTypeName,
			   char *procedureName,
			   uint16 precedence,
			   bool isLeftAssociative,
			   char *commutatorName,
			   char *negatorName,
			   char *restrictionName,
			   char *joinName,
			   bool canHash,
			   char *leftSortName,
			   char *rightSortName)
{
	if (!leftTypeName && !rightTypeName)
		elog(ERROR, "at least one of leftarg or rightarg must be specified");

	if (!(leftTypeName && rightTypeName))
	{
		/* If it's not a binary op, these things mustn't be set: */
		if (commutatorName)
			elog(ERROR, "only binary operators can have commutators");
		if (joinName)
			elog(ERROR, "only binary operators can have join selectivity");
		if (canHash)
			elog(ERROR, "only binary operators can hash");
		if (leftSortName || rightSortName)
			elog(ERROR, "only binary operators can have sort links");
	}

	/*
	 * Use OperatorDef() to define the specified operator and also create
	 * shells for the operator's associated operators if they don't
	 * already exist.
	 */
	OperatorDef(operatorName,
				leftTypeName,
				rightTypeName,
				procedureName,
				precedence,
				isLeftAssociative,
				commutatorName,
				negatorName,
				restrictionName,
				joinName,
				canHash,
				leftSortName,
				rightSortName);
}
