postgresql/src/include/nodes/params.h

/*-------------------------------------------------------------------------
 *
 * params.h
 *	  Declarations/definitions of stuff needed to handle parameterized plans.
 *
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 * $Id: params.h,v 1.10 1999/02/13 23:21:38 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef PARAMS_H
#define PARAMS_H

#include <access/attnum.h>

/* ----------------------------------------------------------------
 *
 * The following are the possible values for the 'paramkind'
 * field of a Param node.
 *
 * PARAM_NAMED: The parameter has a name, i.e. something
 *				like `$.salary' or `$.foobar'.
 *				In this case field `paramname' must be a valid Name.
 *				and field `paramid' must be == 0.
 *
 * PARAM_NUM:	The parameter has only a numeric identifier,
 *				i.e. something like `$1', `$2' etc.
 *				The number is contained in the `parmid' field.
 *
 * PARAM_NEW:	Used in PRS2 rule, similar to PARAM_NAMED.
 *				The `paramname' & `paramid' refer to the "NEW" tuple
 *				`paramname' is the attribute name and `paramid' its
 *				attribute number.
 *
 * PARAM_OLD:	Same as PARAM_NEW, but in this case we refer to
 *				the "OLD" tuple.
 *
 * PARAM_EXEC:	Evaluated by executor. Used for subselect...
 *
 */

#define PARAM_NAMED		11
#define PARAM_NUM		12
#define PARAM_NEW		13
#define PARAM_OLD		14
#define PARAM_EXEC		15
#define PARAM_INVALID	100


/* ----------------------------------------------------------------
 *	  ParamListInfo
 *
 *	  Information needed in order for the executor to handle
 *	  parameterized plans (you know,  $.salary, $.name etc. stuff...).
 *
 *	  ParamListInfoData contains information needed when substituting a
 *	  Param node with a Const node.
 *
 *		kind   : the kind of parameter.
 *		name   : the parameter name (valid if kind == PARAM_NAMED,
 *				 PARAM_NEW or PARAM_OLD)
 *		id	   : the parameter id (valid if kind == PARAM_NUM)
 *				 or the attrno (if kind == PARAM_NEW or PARAM_OLD)
 *		type   : PG_TYPE OID of the value
 *		length : length in bytes of the value
 *		isnull : true if & only if the value is null (if true then
 *				 the fields 'length' and 'value' are undefined).
 *		value  : the value that has to be substituted in the place
 *				 of the parameter.
 *
 *	 ParamListInfo is to be used as an array of ParamListInfoData
 *	 records. An 'InvalidName' in the name field of such a record
 *	 indicates that this is the last record in the array.
 *
 * ----------------------------------------------------------------
 */

typedef struct ParamListInfoData
{
	int			kind;
	char	   *name;
	AttrNumber	id;
	Oid			type;
	Size		length;
	bool		isnull;
	bool		byval;
	Datum		value;
} ParamListInfoData;

typedef ParamListInfoData *ParamListInfo;

typedef struct ParamExecData
{
	void	   *execPlan;		/* plan must be executed to get param
								 * value */
	Datum		value;
	bool		isnull;
} ParamExecData;

#endif	 /* PARAMS_H */