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functioncmds.c

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  • functioncmds.c 48.71 KiB
    /*-------------------------------------------------------------------------
     *
     * functioncmds.c
     *
     *	  Routines for CREATE and DROP FUNCTION commands and CREATE and DROP
     *	  CAST commands.
     *
     * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
     * Portions Copyright (c) 1994, Regents of the University of California
     *
     *
     * IDENTIFICATION
     *	  src/backend/commands/functioncmds.c
     *
     * DESCRIPTION
     *	  These routines take the parse tree and pick out the
     *	  appropriate arguments/flags, and pass the results to the
     *	  corresponding "FooDefine" routines (in src/catalog) that do
     *	  the actual catalog-munging.  These routines also verify permission
     *	  of the user to execute the command.
     *
     * NOTES
     *	  These things must be defined and committed in the following order:
     *		"create function":
     *				input/output, recv/send procedures
     *		"create type":
     *				type
     *		"create operator":
     *				operators
     *
     *-------------------------------------------------------------------------
     */
    #include "postgres.h"
    
    #include "access/genam.h"
    #include "access/heapam.h"
    #include "access/htup_details.h"
    #include "access/sysattr.h"
    #include "catalog/dependency.h"
    #include "catalog/indexing.h"
    #include "catalog/objectaccess.h"
    #include "catalog/pg_aggregate.h"
    #include "catalog/pg_cast.h"
    #include "catalog/pg_language.h"
    #include "catalog/pg_namespace.h"
    #include "catalog/pg_proc.h"
    #include "catalog/pg_proc_fn.h"
    #include "catalog/pg_type.h"
    #include "catalog/pg_type_fn.h"
    #include "commands/alter.h"
    #include "commands/defrem.h"
    #include "commands/proclang.h"
    #include "miscadmin.h"
    #include "optimizer/var.h"
    #include "parser/parse_coerce.h"
    #include "parser/parse_collate.h"
    #include "parser/parse_expr.h"
    #include "parser/parse_func.h"
    #include "parser/parse_type.h"
    #include "utils/acl.h"
    #include "utils/builtins.h"
    #include "utils/fmgroids.h"
    #include "utils/guc.h"
    #include "utils/lsyscache.h"
    #include "utils/rel.h"
    #include "utils/syscache.h"
    #include "utils/tqual.h"
    
    /*
     *	 Examine the RETURNS clause of the CREATE FUNCTION statement
     *	 and return information about it as *prorettype_p and *returnsSet.
     *
     * This is more complex than the average typename lookup because we want to
     * allow a shell type to be used, or even created if the specified return type
     * doesn't exist yet.  (Without this, there's no way to define the I/O procs
     * for a new type.)  But SQL function creation won't cope, so error out if
     * the target language is SQL.	(We do this here, not in the SQL-function
     * validator, so as not to produce a NOTICE and then an ERROR for the same
     * condition.)
     */
    static void
    compute_return_type(TypeName *returnType, Oid languageOid,
    					Oid *prorettype_p, bool *returnsSet_p)
    {
    	Oid			rettype;
    	Type		typtup;
    	AclResult	aclresult;
    
    	typtup = LookupTypeName(NULL, returnType, NULL);
    
    
    	if (typtup)
    	{
    		if (!((Form_pg_type) GETSTRUCT(typtup))->typisdefined)
    		{
    			if (languageOid == SQLlanguageId)
    				ereport(ERROR,
    						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    						 errmsg("SQL function cannot return shell type %s",
    								TypeNameToString(returnType))));
    			else
    				ereport(NOTICE,
    						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
    						 errmsg("return type %s is only a shell",
    								TypeNameToString(returnType))));
    		}
    		rettype = typeTypeId(typtup);
    		ReleaseSysCache(typtup);
    	}
    	else
    	{
    		char	   *typnam = TypeNameToString(returnType);
    		Oid			namespaceId;
    		AclResult	aclresult;
    		char	   *typname;
    
    		/*
    		 * Only C-coded functions can be I/O functions.  We enforce this
    		 * restriction here mainly to prevent littering the catalogs with
    		 * shell types due to simple typos in user-defined function
    		 * definitions.
    		 */
    		if (languageOid != INTERNALlanguageId &&
    			languageOid != ClanguageId)
    			ereport(ERROR,
    					(errcode(ERRCODE_UNDEFINED_OBJECT),
    					 errmsg("type \"%s\" does not exist", typnam)));
    
    		/* Reject if there's typmod decoration, too */
    		if (returnType->typmods != NIL)
    			ereport(ERROR,
    					(errcode(ERRCODE_SYNTAX_ERROR),
    			errmsg("type modifier cannot be specified for shell type \"%s\"",
    				   typnam)));
    
    		/* Otherwise, go ahead and make a shell type */
    		ereport(NOTICE,
    				(errcode(ERRCODE_UNDEFINED_OBJECT),
    				 errmsg("type \"%s\" is not yet defined", typnam),
    				 errdetail("Creating a shell type definition.")));
    		namespaceId = QualifiedNameGetCreationNamespace(returnType->names,
    														&typname);
    		aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
    										  ACL_CREATE);
    		if (aclresult != ACLCHECK_OK)
    			aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
    						   get_namespace_name(namespaceId));
    		rettype = TypeShellMake(typname, namespaceId, GetUserId());
    		Assert(OidIsValid(rettype));
    	}
    
    	aclresult = pg_type_aclcheck(rettype, GetUserId(), ACL_USAGE);
    	if (aclresult != ACLCHECK_OK)
    		aclcheck_error_type(aclresult, rettype);
    
    	*prorettype_p = rettype;
    	*returnsSet_p = returnType->setof;
    }
    
    /*
     * Interpret the parameter list of the CREATE FUNCTION statement.
     *
     * Results are stored into output parameters.  parameterTypes must always
     * be created, but the other arrays are set to NULL if not needed.
     * requiredResultType is set to InvalidOid if there are no OUT parameters,
     * else it is set to the OID of the implied result type.
     */
    static void
    examine_parameter_list(List *parameters, Oid languageOid,
    					   const char *queryString,
    					   oidvector **parameterTypes,
    					   ArrayType **allParameterTypes,
    					   ArrayType **parameterModes,
    					   ArrayType **parameterNames,
    					   List **parameterDefaults,
    					   Oid *requiredResultType)
    {
    	int			parameterCount = list_length(parameters);
    	Oid		   *inTypes;
    	int			inCount = 0;
    	Datum	   *allTypes;
    	Datum	   *paramModes;
    	Datum	   *paramNames;
    	int			outCount = 0;
    	int			varCount = 0;
    	bool		have_names = false;
    	bool		have_defaults = false;
    	ListCell   *x;
    	int			i;
    	ParseState *pstate;
    
    	*requiredResultType = InvalidOid;	/* default result */
    
    	inTypes = (Oid *) palloc(parameterCount * sizeof(Oid));
    	allTypes = (Datum *) palloc(parameterCount * sizeof(Datum));
    	paramModes = (Datum *) palloc(parameterCount * sizeof(Datum));
    	paramNames = (Datum *) palloc0(parameterCount * sizeof(Datum));
    	*parameterDefaults = NIL;
    
    	/* may need a pstate for parse analysis of default exprs */
    	pstate = make_parsestate(NULL);
    	pstate->p_sourcetext = queryString;
    
    	/* Scan the list and extract data into work arrays */
    	i = 0;
    	foreach(x, parameters)
    	{
    		FunctionParameter *fp = (FunctionParameter *) lfirst(x);
    		TypeName   *t = fp->argType;
    		bool		isinput = false;
    		Oid			toid;
    		Type		typtup;
    		AclResult	aclresult;
    
    		typtup = LookupTypeName(NULL, t, NULL);
    		if (typtup)
    		{
    			if (!((Form_pg_type) GETSTRUCT(typtup))->typisdefined)
    			{
    				/* As above, hard error if language is SQL */
    				if (languageOid == SQLlanguageId)
    					ereport(ERROR,
    							(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    						   errmsg("SQL function cannot accept shell type %s",
    								  TypeNameToString(t))));
    				else
    					ereport(NOTICE,
    							(errcode(ERRCODE_WRONG_OBJECT_TYPE),
    							 errmsg("argument type %s is only a shell",
    									TypeNameToString(t))));
    			}
    			toid = typeTypeId(typtup);
    			ReleaseSysCache(typtup);
    		}
    		else
    		{
    			ereport(ERROR,
    					(errcode(ERRCODE_UNDEFINED_OBJECT),
    					 errmsg("type %s does not exist",
    							TypeNameToString(t))));
    			toid = InvalidOid;	/* keep compiler quiet */
    		}
    
    		aclresult = pg_type_aclcheck(toid, GetUserId(), ACL_USAGE);
    		if (aclresult != ACLCHECK_OK)
    			aclcheck_error_type(aclresult, toid);
    
    		if (t->setof)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    					 errmsg("functions cannot accept set arguments")));
    
    		/* handle input parameters */
    		if (fp->mode != FUNC_PARAM_OUT && fp->mode != FUNC_PARAM_TABLE)
    		{
    			/* other input parameters can't follow a VARIADIC parameter */
    			if (varCount > 0)
    				ereport(ERROR,
    						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    						 errmsg("VARIADIC parameter must be the last input parameter")));
    			inTypes[inCount++] = toid;
    			isinput = true;
    		}
    
    		/* handle output parameters */
    		if (fp->mode != FUNC_PARAM_IN && fp->mode != FUNC_PARAM_VARIADIC)
    		{
    			if (outCount == 0)	/* save first output param's type */
    				*requiredResultType = toid;
    			outCount++;
    		}
    
    		if (fp->mode == FUNC_PARAM_VARIADIC)
    		{
    			varCount++;
    			/* validate variadic parameter type */
    			switch (toid)
    			{
    				case ANYARRAYOID:
    				case ANYOID:
    					/* okay */
    					break;
    				default:
    					if (!OidIsValid(get_element_type(toid)))
    						ereport(ERROR,
    								(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    							 errmsg("VARIADIC parameter must be an array")));
    					break;
    			}
    		}
    
    		allTypes[i] = ObjectIdGetDatum(toid);
    
    		paramModes[i] = CharGetDatum(fp->mode);
    
    		if (fp->name && fp->name[0])
    		{
    			ListCell   *px;
    
    			/*
    			 * As of Postgres 9.0 we disallow using the same name for two
    			 * input or two output function parameters.  Depending on the
    			 * function's language, conflicting input and output names might
    			 * be bad too, but we leave it to the PL to complain if so.
    			 */
    			foreach(px, parameters)
    			{
    				FunctionParameter *prevfp = (FunctionParameter *) lfirst(px);
    
    				if (prevfp == fp)
    					break;
    				/* pure in doesn't conflict with pure out */
    				if ((fp->mode == FUNC_PARAM_IN ||
    					 fp->mode == FUNC_PARAM_VARIADIC) &&
    					(prevfp->mode == FUNC_PARAM_OUT ||
    					 prevfp->mode == FUNC_PARAM_TABLE))
    					continue;
    				if ((prevfp->mode == FUNC_PARAM_IN ||
    					 prevfp->mode == FUNC_PARAM_VARIADIC) &&
    					(fp->mode == FUNC_PARAM_OUT ||
    					 fp->mode == FUNC_PARAM_TABLE))
    					continue;
    				if (prevfp->name && prevfp->name[0] &&
    					strcmp(prevfp->name, fp->name) == 0)
    					ereport(ERROR,
    							(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    						  errmsg("parameter name \"%s\" used more than once",
    								 fp->name)));
    			}
    
    			paramNames[i] = CStringGetTextDatum(fp->name);
    			have_names = true;
    		}
    
    		if (fp->defexpr)
    		{
    			Node	   *def;
    
    			if (!isinput)
    				ereport(ERROR,
    						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    				   errmsg("only input parameters can have default values")));
    
    			def = transformExpr(pstate, fp->defexpr,
    								EXPR_KIND_FUNCTION_DEFAULT);
    			def = coerce_to_specific_type(pstate, def, toid, "DEFAULT");
    			assign_expr_collations(pstate, def);
    
    			/*
    			 * Make sure no variables are referred to (this is probably dead
    			 * code now that add_missing_from is history).
    			 */
    			if (list_length(pstate->p_rtable) != 0 ||
    				contain_var_clause(def))
    				ereport(ERROR,
    						(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
    						 errmsg("cannot use table references in parameter default value")));
    
    			/*
    			 * transformExpr() should have already rejected subqueries,
    			 * aggregates, and window functions, based on the EXPR_KIND_ for a
    			 * default expression.
    			 *
    			 * It can't return a set either --- but coerce_to_specific_type
    			 * already checked that for us.
    			 *
    			 * Note: the point of these restrictions is to ensure that an
    			 * expression that, on its face, hasn't got subplans, aggregates,
    			 * etc cannot suddenly have them after function default arguments
    			 * are inserted.
    			 */
    
    			*parameterDefaults = lappend(*parameterDefaults, def);
    			have_defaults = true;
    		}
    		else
    		{
    			if (isinput && have_defaults)
    				ereport(ERROR,
    						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    						 errmsg("input parameters after one with a default value must also have defaults")));
    		}
    
    		i++;
    	}
    
    	free_parsestate(pstate);
    
    	/* Now construct the proper outputs as needed */
    	*parameterTypes = buildoidvector(inTypes, inCount);
    
    	if (outCount > 0 || varCount > 0)
    	{
    		*allParameterTypes = construct_array(allTypes, parameterCount, OIDOID,
    											 sizeof(Oid), true, 'i');
    		*parameterModes = construct_array(paramModes, parameterCount, CHAROID,
    										  1, true, 'c');
    		if (outCount > 1)
    			*requiredResultType = RECORDOID;
    		/* otherwise we set requiredResultType correctly above */
    	}
    	else
    	{
    		*allParameterTypes = NULL;
    		*parameterModes = NULL;
    	}
    
    	if (have_names)
    	{
    		for (i = 0; i < parameterCount; i++)
    		{
    			if (paramNames[i] == PointerGetDatum(NULL))
    				paramNames[i] = CStringGetTextDatum("");
    		}
    		*parameterNames = construct_array(paramNames, parameterCount, TEXTOID,
    										  -1, false, 'i');
    	}
    	else
    		*parameterNames = NULL;
    }
    
    
    /*
     * Recognize one of the options that can be passed to both CREATE
     * FUNCTION and ALTER FUNCTION and return it via one of the out
     * parameters. Returns true if the passed option was recognized. If
     * the out parameter we were going to assign to points to non-NULL,
     * raise a duplicate-clause error.	(We don't try to detect duplicate
     * SET parameters though --- if you're redundant, the last one wins.)
     */
    static bool
    compute_common_attribute(DefElem *defel,
    						 DefElem **volatility_item,
    						 DefElem **strict_item,
    						 DefElem **security_item,
    						 DefElem **leakproof_item,
    						 List **set_items,
    						 DefElem **cost_item,
    						 DefElem **rows_item)
    {
    	if (strcmp(defel->defname, "volatility") == 0)
    	{
    		if (*volatility_item)
    			goto duplicate_error;
    
    		*volatility_item = defel;
    	}
    	else if (strcmp(defel->defname, "strict") == 0)
    	{
    		if (*strict_item)
    			goto duplicate_error;
    
    		*strict_item = defel;
    	}
    	else if (strcmp(defel->defname, "security") == 0)
    	{
    		if (*security_item)
    			goto duplicate_error;
    
    		*security_item = defel;
    	}
    	else if (strcmp(defel->defname, "leakproof") == 0)
    	{
    		if (*leakproof_item)
    			goto duplicate_error;
    
    		*leakproof_item = defel;
    	}
    	else if (strcmp(defel->defname, "set") == 0)
    	{
    		*set_items = lappend(*set_items, defel->arg);
    	}
    	else if (strcmp(defel->defname, "cost") == 0)
    	{
    		if (*cost_item)
    			goto duplicate_error;
    
    		*cost_item = defel;
    	}
    	else if (strcmp(defel->defname, "rows") == 0)
    	{
    		if (*rows_item)
    			goto duplicate_error;
    
    		*rows_item = defel;
    	}
    	else
    		return false;
    
    	/* Recognized an option */
    	return true;
    
    duplicate_error:
    	ereport(ERROR,
    			(errcode(ERRCODE_SYNTAX_ERROR),
    			 errmsg("conflicting or redundant options")));
    	return false;				/* keep compiler quiet */
    }
    
    static char
    interpret_func_volatility(DefElem *defel)
    {
    	char	   *str = strVal(defel->arg);
    
    	if (strcmp(str, "immutable") == 0)
    		return PROVOLATILE_IMMUTABLE;
    	else if (strcmp(str, "stable") == 0)
    		return PROVOLATILE_STABLE;
    	else if (strcmp(str, "volatile") == 0)
    		return PROVOLATILE_VOLATILE;
    	else
    	{
    		elog(ERROR, "invalid volatility \"%s\"", str);
    		return 0;				/* keep compiler quiet */
    	}
    }
    
    /*
     * Update a proconfig value according to a list of VariableSetStmt items.
     *
     * The input and result may be NULL to signify a null entry.
     */
    static ArrayType *
    update_proconfig_value(ArrayType *a, List *set_items)
    {
    	ListCell   *l;
    
    	foreach(l, set_items)
    	{
    		VariableSetStmt *sstmt = (VariableSetStmt *) lfirst(l);
    
    		Assert(IsA(sstmt, VariableSetStmt));
    		if (sstmt->kind == VAR_RESET_ALL)
    			a = NULL;
    		else
    		{
    			char	   *valuestr = ExtractSetVariableArgs(sstmt);
    
    			if (valuestr)
    				a = GUCArrayAdd(a, sstmt->name, valuestr);
    			else	/* RESET */
    				a = GUCArrayDelete(a, sstmt->name);
    		}
    	}
    
    	return a;
    }
    
    
    /*
     * Dissect the list of options assembled in gram.y into function
     * attributes.
     */
    static void
    compute_attributes_sql_style(List *options,
    							 List **as,
    							 char **language,
    							 bool *windowfunc_p,
    							 char *volatility_p,
    							 bool *strict_p,
    							 bool *security_definer,
    							 bool *leakproof_p,
    							 ArrayType **proconfig,
    							 float4 *procost,
    							 float4 *prorows)
    {
    	ListCell   *option;
    	DefElem    *as_item = NULL;
    	DefElem    *language_item = NULL;
    	DefElem    *windowfunc_item = NULL;
    	DefElem    *volatility_item = NULL;
    	DefElem    *strict_item = NULL;
    	DefElem    *security_item = NULL;
    	DefElem    *leakproof_item = NULL;
    	List	   *set_items = NIL;
    	DefElem    *cost_item = NULL;
    	DefElem    *rows_item = NULL;
    
    	foreach(option, options)
    	{
    		DefElem    *defel = (DefElem *) lfirst(option);
    
    		if (strcmp(defel->defname, "as") == 0)
    		{
    			if (as_item)
    				ereport(ERROR,
    						(errcode(ERRCODE_SYNTAX_ERROR),
    						 errmsg("conflicting or redundant options")));
    			as_item = defel;
    		}
    		else if (strcmp(defel->defname, "language") == 0)
    		{
    			if (language_item)
    				ereport(ERROR,
    						(errcode(ERRCODE_SYNTAX_ERROR),
    						 errmsg("conflicting or redundant options")));
    			language_item = defel;
    		}
    		else if (strcmp(defel->defname, "window") == 0)
    		{
    			if (windowfunc_item)
    				ereport(ERROR,
    						(errcode(ERRCODE_SYNTAX_ERROR),
    						 errmsg("conflicting or redundant options")));
    			windowfunc_item = defel;
    		}
    		else if (compute_common_attribute(defel,
    										  &volatility_item,
    										  &strict_item,
    										  &security_item,
    										  &leakproof_item,
    										  &set_items,
    										  &cost_item,
    										  &rows_item))
    		{
    			/* recognized common option */
    			continue;
    		}
    		else
    			elog(ERROR, "option \"%s\" not recognized",
    				 defel->defname);
    	}
    
    	/* process required items */
    	if (as_item)
    		*as = (List *) as_item->arg;
    	else
    	{
    		ereport(ERROR,
    				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    				 errmsg("no function body specified")));
    		*as = NIL;				/* keep compiler quiet */
    	}
    
    	if (language_item)
    		*language = strVal(language_item->arg);
    	else
    	{
    		ereport(ERROR,
    				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    				 errmsg("no language specified")));
    		*language = NULL;		/* keep compiler quiet */
    	}
    
    	/* process optional items */
    	if (windowfunc_item)
    		*windowfunc_p = intVal(windowfunc_item->arg);
    	if (volatility_item)
    		*volatility_p = interpret_func_volatility(volatility_item);
    	if (strict_item)
    		*strict_p = intVal(strict_item->arg);
    	if (security_item)
    		*security_definer = intVal(security_item->arg);
    	if (leakproof_item)
    		*leakproof_p = intVal(leakproof_item->arg);
    	if (set_items)
    		*proconfig = update_proconfig_value(NULL, set_items);
    	if (cost_item)
    	{
    		*procost = defGetNumeric(cost_item);
    		if (*procost <= 0)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
    					 errmsg("COST must be positive")));
    	}
    	if (rows_item)
    	{
    		*prorows = defGetNumeric(rows_item);
    		if (*prorows <= 0)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
    					 errmsg("ROWS must be positive")));
    	}
    }
    
    
    /*-------------
     *	 Interpret the parameters *parameters and return their contents via
     *	 *isStrict_p and *volatility_p.
     *
     *	These parameters supply optional information about a function.
     *	All have defaults if not specified. Parameters:
     *
     *	 * isStrict means the function should not be called when any NULL
     *	   inputs are present; instead a NULL result value should be assumed.
     *
     *	 * volatility tells the optimizer whether the function's result can
     *	   be assumed to be repeatable over multiple evaluations.
     *------------
     */
    static void
    compute_attributes_with_style(List *parameters, bool *isStrict_p, char *volatility_p)
    {
    	ListCell   *pl;
    
    	foreach(pl, parameters)
    	{
    		DefElem    *param = (DefElem *) lfirst(pl);
    
    		if (pg_strcasecmp(param->defname, "isstrict") == 0)
    			*isStrict_p = defGetBoolean(param);
    		else if (pg_strcasecmp(param->defname, "iscachable") == 0)
    		{
    			/* obsolete spelling of isImmutable */
    			if (defGetBoolean(param))
    				*volatility_p = PROVOLATILE_IMMUTABLE;
    		}
    		else
    			ereport(WARNING,
    					(errcode(ERRCODE_SYNTAX_ERROR),
    					 errmsg("unrecognized function attribute \"%s\" ignored",
    							param->defname)));
    	}
    }
    
    
    /*
     * For a dynamically linked C language object, the form of the clause is
     *
     *	   AS <object file name> [, <link symbol name> ]
     *
     * In all other cases
     *
     *	   AS <object reference, or sql code>
     */
    static void
    interpret_AS_clause(Oid languageOid, const char *languageName,
    					char *funcname, List *as,
    					char **prosrc_str_p, char **probin_str_p)
    {
    	Assert(as != NIL);
    
    	if (languageOid == ClanguageId)
    	{
    		/*
    		 * For "C" language, store the file name in probin and, when given,
    		 * the link symbol name in prosrc.	If link symbol is omitted,
    		 * substitute procedure name.  We also allow link symbol to be
    		 * specified as "-", since that was the habit in PG versions before
    		 * 8.4, and there might be dump files out there that don't translate
    		 * that back to "omitted".
    		 */
    		*probin_str_p = strVal(linitial(as));
    		if (list_length(as) == 1)
    			*prosrc_str_p = funcname;
    		else
    		{
    			*prosrc_str_p = strVal(lsecond(as));
    			if (strcmp(*prosrc_str_p, "-") == 0)
    				*prosrc_str_p = funcname;
    		}
    	}
    	else
    	{
    		/* Everything else wants the given string in prosrc. */
    		*prosrc_str_p = strVal(linitial(as));
    		*probin_str_p = NULL;
    
    		if (list_length(as) != 1)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    					 errmsg("only one AS item needed for language \"%s\"",
    							languageName)));
    
    		if (languageOid == INTERNALlanguageId)
    		{
    			/*
    			 * In PostgreSQL versions before 6.5, the SQL name of the created
    			 * function could not be different from the internal name, and
    			 * "prosrc" wasn't used.  So there is code out there that does
    			 * CREATE FUNCTION xyz AS '' LANGUAGE internal. To preserve some
    			 * modicum of backwards compatibility, accept an empty "prosrc"
    			 * value as meaning the supplied SQL function name.
    			 */
    			if (strlen(*prosrc_str_p) == 0)
    				*prosrc_str_p = funcname;
    		}
    	}
    }
    
    
    
    /*
     * CreateFunction
     *	 Execute a CREATE FUNCTION utility statement.
     */
    Oid
    CreateFunction(CreateFunctionStmt *stmt, const char *queryString)
    {
    	char	   *probin_str;
    	char	   *prosrc_str;
    	Oid			prorettype;
    	bool		returnsSet;
    	char	   *language;
    	Oid			languageOid;
    	Oid			languageValidator;
    	char	   *funcname;
    	Oid			namespaceId;
    	AclResult	aclresult;
    	oidvector  *parameterTypes;
    	ArrayType  *allParameterTypes;
    	ArrayType  *parameterModes;
    	ArrayType  *parameterNames;
    	List	   *parameterDefaults;
    	Oid			requiredResultType;
    	bool		isWindowFunc,
    				isStrict,
    				security,
    				isLeakProof;
    	char		volatility;
    	ArrayType  *proconfig;
    	float4		procost;
    	float4		prorows;
    	HeapTuple	languageTuple;
    	Form_pg_language languageStruct;
    	List	   *as_clause;
    
    	/* Convert list of names to a name and namespace */
    	namespaceId = QualifiedNameGetCreationNamespace(stmt->funcname,
    													&funcname);
    
    	/* Check we have creation rights in target namespace */
    	aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
    	if (aclresult != ACLCHECK_OK)
    		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
    					   get_namespace_name(namespaceId));
    
    	/* default attributes */
    	isWindowFunc = false;
    	isStrict = false;
    	security = false;
    	isLeakProof = false;
    	volatility = PROVOLATILE_VOLATILE;
    	proconfig = NULL;
    	procost = -1;				/* indicates not set */
    	prorows = -1;				/* indicates not set */
    
    	/* override attributes from explicit list */
    	compute_attributes_sql_style(stmt->options,
    								 &as_clause, &language,
    								 &isWindowFunc, &volatility,
    								 &isStrict, &security, &isLeakProof,
    								 &proconfig, &procost, &prorows);
    
    	/* Look up the language and validate permissions */
    	languageTuple = SearchSysCache1(LANGNAME, PointerGetDatum(language));
    	if (!HeapTupleIsValid(languageTuple))
    		ereport(ERROR,
    				(errcode(ERRCODE_UNDEFINED_OBJECT),
    				 errmsg("language \"%s\" does not exist", language),
    				 (PLTemplateExists(language) ?
    				  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));
    
    	languageOid = HeapTupleGetOid(languageTuple);
    	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
    
    	if (languageStruct->lanpltrusted)
    	{
    		/* if trusted language, need USAGE privilege */
    		AclResult	aclresult;
    
    		aclresult = pg_language_aclcheck(languageOid, GetUserId(), ACL_USAGE);
    		if (aclresult != ACLCHECK_OK)
    			aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
    						   NameStr(languageStruct->lanname));
    	}
    	else
    	{
    		/* if untrusted language, must be superuser */
    		if (!superuser())
    			aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
    						   NameStr(languageStruct->lanname));
    	}
    
    	languageValidator = languageStruct->lanvalidator;
    
    	ReleaseSysCache(languageTuple);
    
    	/*
    	 * Only superuser is allowed to create leakproof functions because it
    	 * possibly allows unprivileged users to reference invisible tuples to be
    	 * filtered out using views for row-level security.
    	 */
    	if (isLeakProof && !superuser())
    		ereport(ERROR,
    				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
    				 errmsg("only superuser can define a leakproof function")));
    
    	/*
    	 * Convert remaining parameters of CREATE to form wanted by
    	 * ProcedureCreate.
    	 */
    	examine_parameter_list(stmt->parameters, languageOid, queryString,
    						   &parameterTypes,
    						   &allParameterTypes,
    						   &parameterModes,
    						   &parameterNames,
    						   &parameterDefaults,
    						   &requiredResultType);
    
    	if (stmt->returnType)
    	{
    		/* explicit RETURNS clause */
    		compute_return_type(stmt->returnType, languageOid,
    							&prorettype, &returnsSet);
    		if (OidIsValid(requiredResultType) && prorettype != requiredResultType)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    					 errmsg("function result type must be %s because of OUT parameters",
    							format_type_be(requiredResultType))));
    	}
    	else if (OidIsValid(requiredResultType))
    	{
    		/* default RETURNS clause from OUT parameters */
    		prorettype = requiredResultType;
    		returnsSet = false;
    	}
    	else
    	{
    		ereport(ERROR,
    				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
    				 errmsg("function result type must be specified")));
    		/* Alternative possibility: default to RETURNS VOID */
    		prorettype = VOIDOID;
    		returnsSet = false;
    	}
    
    	compute_attributes_with_style(stmt->withClause, &isStrict, &volatility);
    
    	interpret_AS_clause(languageOid, language, funcname, as_clause,
    						&prosrc_str, &probin_str);
    
    	/*
    	 * Set default values for COST and ROWS depending on other parameters;
    	 * reject ROWS if it's not returnsSet.  NB: pg_dump knows these default
    	 * values, keep it in sync if you change them.
    	 */
    	if (procost < 0)
    	{
    		/* SQL and PL-language functions are assumed more expensive */
    		if (languageOid == INTERNALlanguageId ||
    			languageOid == ClanguageId)
    			procost = 1;
    		else
    			procost = 100;
    	}
    	if (prorows < 0)
    	{
    		if (returnsSet)
    			prorows = 1000;
    		else
    			prorows = 0;		/* dummy value if not returnsSet */
    	}
    	else if (!returnsSet)
    		ereport(ERROR,
    				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
    				 errmsg("ROWS is not applicable when function does not return a set")));
    
    	/*
    	 * And now that we have all the parameters, and know we're permitted to do
    	 * so, go ahead and create the function.
    	 */
    	return ProcedureCreate(funcname,
    						   namespaceId,
    						   stmt->replace,
    						   returnsSet,
    						   prorettype,
    						   GetUserId(),
    						   languageOid,
    						   languageValidator,
    						   prosrc_str,	/* converted to text later */
    						   probin_str,	/* converted to text later */
    						   false,		/* not an aggregate */
    						   isWindowFunc,
    						   security,
    						   isLeakProof,
    						   isStrict,
    						   volatility,
    						   parameterTypes,
    						   PointerGetDatum(allParameterTypes),
    						   PointerGetDatum(parameterModes),
    						   PointerGetDatum(parameterNames),
    						   parameterDefaults,
    						   PointerGetDatum(proconfig),
    						   procost,
    						   prorows);
    }
    
    
    /*
     * Guts of function deletion.
     *
     * Note: this is also used for aggregate deletion, since the OIDs of
     * both functions and aggregates point to pg_proc.
     */
    void
    RemoveFunctionById(Oid funcOid)
    {
    	Relation	relation;
    	HeapTuple	tup;
    	bool		isagg;
    
    	/*
    	 * Delete the pg_proc tuple.
    	 */
    	relation = heap_open(ProcedureRelationId, RowExclusiveLock);
    
    	tup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcOid));
    	if (!HeapTupleIsValid(tup)) /* should not happen */
    		elog(ERROR, "cache lookup failed for function %u", funcOid);
    
    	isagg = ((Form_pg_proc) GETSTRUCT(tup))->proisagg;
    
    	simple_heap_delete(relation, &tup->t_self);
    
    	ReleaseSysCache(tup);
    
    	heap_close(relation, RowExclusiveLock);
    
    	/*
    	 * If there's a pg_aggregate tuple, delete that too.
    	 */
    	if (isagg)
    	{
    		relation = heap_open(AggregateRelationId, RowExclusiveLock);
    
    		tup = SearchSysCache1(AGGFNOID, ObjectIdGetDatum(funcOid));
    		if (!HeapTupleIsValid(tup))		/* should not happen */
    			elog(ERROR, "cache lookup failed for pg_aggregate tuple for function %u", funcOid);
    
    		simple_heap_delete(relation, &tup->t_self);
    
    		ReleaseSysCache(tup);
    
    		heap_close(relation, RowExclusiveLock);
    	}
    }
    
    /*
     * Implements the ALTER FUNCTION utility command (except for the
     * RENAME and OWNER clauses, which are handled as part of the generic
     * ALTER framework).
     */
    Oid
    AlterFunction(AlterFunctionStmt *stmt)
    {
    	HeapTuple	tup;
    	Oid			funcOid;
    	Form_pg_proc procForm;
    	Relation	rel;
    	ListCell   *l;
    	DefElem    *volatility_item = NULL;
    	DefElem    *strict_item = NULL;
    	DefElem    *security_def_item = NULL;
    	DefElem    *leakproof_item = NULL;
    	List	   *set_items = NIL;
    	DefElem    *cost_item = NULL;
    	DefElem    *rows_item = NULL;
    
    	rel = heap_open(ProcedureRelationId, RowExclusiveLock);
    
    	funcOid = LookupFuncNameTypeNames(stmt->func->funcname,
    									  stmt->func->funcargs,
    									  false);
    
    	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
    	if (!HeapTupleIsValid(tup)) /* should not happen */
    		elog(ERROR, "cache lookup failed for function %u", funcOid);
    
    	procForm = (Form_pg_proc) GETSTRUCT(tup);
    
    	/* Permission check: must own function */
    	if (!pg_proc_ownercheck(funcOid, GetUserId()))
    		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC,
    					   NameListToString(stmt->func->funcname));
    
    	if (procForm->proisagg)
    		ereport(ERROR,
    				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
    				 errmsg("\"%s\" is an aggregate function",
    						NameListToString(stmt->func->funcname))));
    
    	/* Examine requested actions. */
    	foreach(l, stmt->actions)
    	{
    		DefElem    *defel = (DefElem *) lfirst(l);
    
    		if (compute_common_attribute(defel,
    									 &volatility_item,
    									 &strict_item,
    									 &security_def_item,
    									 &leakproof_item,
    									 &set_items,
    									 &cost_item,
    									 &rows_item) == false)
    			elog(ERROR, "option \"%s\" not recognized", defel->defname);
    	}
    
    	if (volatility_item)
    		procForm->provolatile = interpret_func_volatility(volatility_item);
    	if (strict_item)
    		procForm->proisstrict = intVal(strict_item->arg);
    	if (security_def_item)
    		procForm->prosecdef = intVal(security_def_item->arg);
    	if (leakproof_item)
    	{
    		if (intVal(leakproof_item->arg) && !superuser())
    			ereport(ERROR,
    					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
    				  errmsg("only superuser can define a leakproof function")));
    		procForm->proleakproof = intVal(leakproof_item->arg);
    	}
    	if (cost_item)
    	{
    		procForm->procost = defGetNumeric(cost_item);
    		if (procForm->procost <= 0)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
    					 errmsg("COST must be positive")));
    	}
    	if (rows_item)
    	{
    		procForm->prorows = defGetNumeric(rows_item);
    		if (procForm->prorows <= 0)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
    					 errmsg("ROWS must be positive")));
    		if (!procForm->proretset)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
    					 errmsg("ROWS is not applicable when function does not return a set")));
    	}
    	if (set_items)
    	{
    		Datum		datum;
    		bool		isnull;
    		ArrayType  *a;
    		Datum		repl_val[Natts_pg_proc];
    		bool		repl_null[Natts_pg_proc];
    		bool		repl_repl[Natts_pg_proc];
    
    		/* extract existing proconfig setting */
    		datum = SysCacheGetAttr(PROCOID, tup, Anum_pg_proc_proconfig, &isnull);
    		a = isnull ? NULL : DatumGetArrayTypeP(datum);
    
    		/* update according to each SET or RESET item, left to right */
    		a = update_proconfig_value(a, set_items);
    
    		/* update the tuple */
    		memset(repl_repl, false, sizeof(repl_repl));
    		repl_repl[Anum_pg_proc_proconfig - 1] = true;
    
    		if (a == NULL)
    		{
    			repl_val[Anum_pg_proc_proconfig - 1] = (Datum) 0;
    			repl_null[Anum_pg_proc_proconfig - 1] = true;
    		}
    		else
    		{
    			repl_val[Anum_pg_proc_proconfig - 1] = PointerGetDatum(a);
    			repl_null[Anum_pg_proc_proconfig - 1] = false;
    		}
    
    		tup = heap_modify_tuple(tup, RelationGetDescr(rel),
    								repl_val, repl_null, repl_repl);
    	}
    
    	/* Do the update */
    	simple_heap_update(rel, &tup->t_self, tup);
    	CatalogUpdateIndexes(rel, tup);
    
    	InvokeObjectPostAlterHook(ProcedureRelationId, funcOid, 0);
    
    	heap_close(rel, NoLock);
    	heap_freetuple(tup);
    
    	return funcOid;
    }
    
    /*
     * SetFunctionReturnType - change declared return type of a function
     *
     * This is presently only used for adjusting legacy functions that return
     * OPAQUE to return whatever we find their correct definition should be.
     * The caller should emit a suitable warning explaining what we did.
     */
    void
    SetFunctionReturnType(Oid funcOid, Oid newRetType)
    {
    	Relation	pg_proc_rel;
    	HeapTuple	tup;
    	Form_pg_proc procForm;
    
    	pg_proc_rel = heap_open(ProcedureRelationId, RowExclusiveLock);
    
    	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
    	if (!HeapTupleIsValid(tup)) /* should not happen */
    		elog(ERROR, "cache lookup failed for function %u", funcOid);
    	procForm = (Form_pg_proc) GETSTRUCT(tup);
    
    	if (procForm->prorettype != OPAQUEOID)		/* caller messed up */
    		elog(ERROR, "function %u doesn't return OPAQUE", funcOid);
    
    	/* okay to overwrite copied tuple */
    	procForm->prorettype = newRetType;
    
    	/* update the catalog and its indexes */
    	simple_heap_update(pg_proc_rel, &tup->t_self, tup);
    
    	CatalogUpdateIndexes(pg_proc_rel, tup);
    
    	heap_close(pg_proc_rel, RowExclusiveLock);
    }
    
    
    /*
     * SetFunctionArgType - change declared argument type of a function
     *
     * As above, but change an argument's type.
     */
    void
    SetFunctionArgType(Oid funcOid, int argIndex, Oid newArgType)
    {
    	Relation	pg_proc_rel;
    	HeapTuple	tup;
    	Form_pg_proc procForm;
    
    	pg_proc_rel = heap_open(ProcedureRelationId, RowExclusiveLock);
    
    	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
    	if (!HeapTupleIsValid(tup)) /* should not happen */
    		elog(ERROR, "cache lookup failed for function %u", funcOid);
    	procForm = (Form_pg_proc) GETSTRUCT(tup);
    
    	if (argIndex < 0 || argIndex >= procForm->pronargs ||
    		procForm->proargtypes.values[argIndex] != OPAQUEOID)
    		elog(ERROR, "function %u doesn't take OPAQUE", funcOid);
    
    	/* okay to overwrite copied tuple */
    	procForm->proargtypes.values[argIndex] = newArgType;
    
    	/* update the catalog and its indexes */
    	simple_heap_update(pg_proc_rel, &tup->t_self, tup);
    
    	CatalogUpdateIndexes(pg_proc_rel, tup);
    
    	heap_close(pg_proc_rel, RowExclusiveLock);
    }
    
    
    
    /*
     * CREATE CAST
     */
    Oid
    CreateCast(CreateCastStmt *stmt)
    {
    	Oid			sourcetypeid;
    	Oid			targettypeid;
    	char		sourcetyptype;
    	char		targettyptype;
    	Oid			funcid;
    	Oid			castid;
    	int			nargs;
    	char		castcontext;
    	char		castmethod;
    	Relation	relation;
    	HeapTuple	tuple;
    	Datum		values[Natts_pg_cast];
    	bool		nulls[Natts_pg_cast];
    	ObjectAddress myself,
    				referenced;
    	AclResult	aclresult;
    
    	sourcetypeid = typenameTypeId(NULL, stmt->sourcetype);
    	targettypeid = typenameTypeId(NULL, stmt->targettype);
    	sourcetyptype = get_typtype(sourcetypeid);
    	targettyptype = get_typtype(targettypeid);
    
    	/* No pseudo-types allowed */
    	if (sourcetyptype == TYPTYPE_PSEUDO)
    		ereport(ERROR,
    				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
    				 errmsg("source data type %s is a pseudo-type",
    						TypeNameToString(stmt->sourcetype))));
    
    	if (targettyptype == TYPTYPE_PSEUDO)
    		ereport(ERROR,
    				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
    				 errmsg("target data type %s is a pseudo-type",
    						TypeNameToString(stmt->targettype))));
    
    	/* Permission check */
    	if (!pg_type_ownercheck(sourcetypeid, GetUserId())
    		&& !pg_type_ownercheck(targettypeid, GetUserId()))
    		ereport(ERROR,
    				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
    				 errmsg("must be owner of type %s or type %s",
    						format_type_be(sourcetypeid),
    						format_type_be(targettypeid))));
    
    	aclresult = pg_type_aclcheck(sourcetypeid, GetUserId(), ACL_USAGE);
    	if (aclresult != ACLCHECK_OK)
    		aclcheck_error_type(aclresult, sourcetypeid);
    
    	aclresult = pg_type_aclcheck(targettypeid, GetUserId(), ACL_USAGE);
    	if (aclresult != ACLCHECK_OK)
    		aclcheck_error_type(aclresult, targettypeid);
    
    	/* Domains are allowed for historical reasons, but we warn */
    	if (sourcetyptype == TYPTYPE_DOMAIN)
    		ereport(WARNING,
    				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
    				 errmsg("cast will be ignored because the source data type is a domain")));
    
    	else if (targettyptype == TYPTYPE_DOMAIN)
    		ereport(WARNING,
    				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
    				 errmsg("cast will be ignored because the target data type is a domain")));
    
    	/* Detemine the cast method */
    	if (stmt->func != NULL)
    		castmethod = COERCION_METHOD_FUNCTION;
    	else if (stmt->inout)
    		castmethod = COERCION_METHOD_INOUT;
    	else
    		castmethod = COERCION_METHOD_BINARY;
    
    	if (castmethod == COERCION_METHOD_FUNCTION)
    	{
    		Form_pg_proc procstruct;
    
    		funcid = LookupFuncNameTypeNames(stmt->func->funcname,
    										 stmt->func->funcargs,
    										 false);
    
    		tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    		if (!HeapTupleIsValid(tuple))
    			elog(ERROR, "cache lookup failed for function %u", funcid);
    
    		procstruct = (Form_pg_proc) GETSTRUCT(tuple);
    		nargs = procstruct->pronargs;
    		if (nargs < 1 || nargs > 3)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    				  errmsg("cast function must take one to three arguments")));
    		if (!IsBinaryCoercible(sourcetypeid, procstruct->proargtypes.values[0]))
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("argument of cast function must match or be binary-coercible from source data type")));
    		if (nargs > 1 && procstruct->proargtypes.values[1] != INT4OID)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    			errmsg("second argument of cast function must be type integer")));
    		if (nargs > 2 && procstruct->proargtypes.values[2] != BOOLOID)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    			errmsg("third argument of cast function must be type boolean")));
    		if (!IsBinaryCoercible(procstruct->prorettype, targettypeid))
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("return data type of cast function must match or be binary-coercible to target data type")));
    
    		/*
    		 * Restricting the volatility of a cast function may or may not be a
    		 * good idea in the abstract, but it definitely breaks many old
    		 * user-defined types.	Disable this check --- tgl 2/1/03
    		 */
    #ifdef NOT_USED
    		if (procstruct->provolatile == PROVOLATILE_VOLATILE)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("cast function must not be volatile")));
    #endif
    		if (procstruct->proisagg)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    				 errmsg("cast function must not be an aggregate function")));
    		if (procstruct->proiswindow)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("cast function must not be a window function")));
    		if (procstruct->proretset)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("cast function must not return a set")));
    
    		ReleaseSysCache(tuple);
    	}
    	else
    	{
    		funcid = InvalidOid;
    		nargs = 0;
    	}
    
    	if (castmethod == COERCION_METHOD_BINARY)
    	{
    		int16		typ1len;
    		int16		typ2len;
    		bool		typ1byval;
    		bool		typ2byval;
    		char		typ1align;
    		char		typ2align;
    
    		/*
    		 * Must be superuser to create binary-compatible casts, since
    		 * erroneous casts can easily crash the backend.
    		 */
    		if (!superuser())
    			ereport(ERROR,
    					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
    			 errmsg("must be superuser to create a cast WITHOUT FUNCTION")));
    
    		/*
    		 * Also, insist that the types match as to size, alignment, and
    		 * pass-by-value attributes; this provides at least a crude check that
    		 * they have similar representations.  A pair of types that fail this
    		 * test should certainly not be equated.
    		 */
    		get_typlenbyvalalign(sourcetypeid, &typ1len, &typ1byval, &typ1align);
    		get_typlenbyvalalign(targettypeid, &typ2len, &typ2byval, &typ2align);
    		if (typ1len != typ2len ||
    			typ1byval != typ2byval ||
    			typ1align != typ2align)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("source and target data types are not physically compatible")));
    
    		/*
    		 * We know that composite, enum and array types are never binary-
    		 * compatible with each other.	They all have OIDs embedded in them.
    		 *
    		 * Theoretically you could build a user-defined base type that is
    		 * binary-compatible with a composite, enum, or array type.  But we
    		 * disallow that too, as in practice such a cast is surely a mistake.
    		 * You can always work around that by writing a cast function.
    		 */
    		if (sourcetyptype == TYPTYPE_COMPOSITE ||
    			targettyptype == TYPTYPE_COMPOSITE)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    				  errmsg("composite data types are not binary-compatible")));
    
    		if (sourcetyptype == TYPTYPE_ENUM ||
    			targettyptype == TYPTYPE_ENUM)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("enum data types are not binary-compatible")));
    
    		if (OidIsValid(get_element_type(sourcetypeid)) ||
    			OidIsValid(get_element_type(targettypeid)))
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("array data types are not binary-compatible")));
    
    		/*
    		 * We also disallow creating binary-compatibility casts involving
    		 * domains.  Casting from a domain to its base type is already
    		 * allowed, and casting the other way ought to go through domain
    		 * coercion to permit constraint checking.	Again, if you're intent on
    		 * having your own semantics for that, create a no-op cast function.
    		 *
    		 * NOTE: if we were to relax this, the above checks for composites
    		 * etc. would have to be modified to look through domains to their
    		 * base types.
    		 */
    		if (sourcetyptype == TYPTYPE_DOMAIN ||
    			targettyptype == TYPTYPE_DOMAIN)
    			ereport(ERROR,
    					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    					 errmsg("domain data types must not be marked binary-compatible")));
    	}
    
    	/*
    	 * Allow source and target types to be same only for length coercion
    	 * functions.  We assume a multi-arg function does length coercion.
    	 */
    	if (sourcetypeid == targettypeid && nargs < 2)
    		ereport(ERROR,
    				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
    			  errmsg("source data type and target data type are the same")));
    
    	/* convert CoercionContext enum to char value for castcontext */
    	switch (stmt->context)
    	{
    		case COERCION_IMPLICIT:
    			castcontext = COERCION_CODE_IMPLICIT;
    			break;
    		case COERCION_ASSIGNMENT:
    			castcontext = COERCION_CODE_ASSIGNMENT;
    			break;
    		case COERCION_EXPLICIT:
    			castcontext = COERCION_CODE_EXPLICIT;
    			break;
    		default:
    			elog(ERROR, "unrecognized CoercionContext: %d", stmt->context);
    			castcontext = 0;	/* keep compiler quiet */
    			break;
    	}
    
    	relation = heap_open(CastRelationId, RowExclusiveLock);
    
    	/*
    	 * Check for duplicate.  This is just to give a friendly error message,
    	 * the unique index would catch it anyway (so no need to sweat about race
    	 * conditions).
    	 */
    	tuple = SearchSysCache2(CASTSOURCETARGET,
    							ObjectIdGetDatum(sourcetypeid),
    							ObjectIdGetDatum(targettypeid));
    	if (HeapTupleIsValid(tuple))
    		ereport(ERROR,
    				(errcode(ERRCODE_DUPLICATE_OBJECT),
    				 errmsg("cast from type %s to type %s already exists",
    						format_type_be(sourcetypeid),
    						format_type_be(targettypeid))));
    
    	/* ready to go */
    	values[Anum_pg_cast_castsource - 1] = ObjectIdGetDatum(sourcetypeid);
    	values[Anum_pg_cast_casttarget - 1] = ObjectIdGetDatum(targettypeid);
    	values[Anum_pg_cast_castfunc - 1] = ObjectIdGetDatum(funcid);
    	values[Anum_pg_cast_castcontext - 1] = CharGetDatum(castcontext);
    	values[Anum_pg_cast_castmethod - 1] = CharGetDatum(castmethod);
    
    	MemSet(nulls, false, sizeof(nulls));
    
    	tuple = heap_form_tuple(RelationGetDescr(relation), values, nulls);
    
    	castid = simple_heap_insert(relation, tuple);
    
    	CatalogUpdateIndexes(relation, tuple);
    
    	/* make dependency entries */
    	myself.classId = CastRelationId;
    	myself.objectId = castid;
    	myself.objectSubId = 0;
    
    	/* dependency on source type */
    	referenced.classId = TypeRelationId;
    	referenced.objectId = sourcetypeid;
    	referenced.objectSubId = 0;
    	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    
    	/* dependency on target type */
    	referenced.classId = TypeRelationId;
    	referenced.objectId = targettypeid;
    	referenced.objectSubId = 0;
    	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    
    	/* dependency on function */
    	if (OidIsValid(funcid))
    	{
    		referenced.classId = ProcedureRelationId;
    		referenced.objectId = funcid;
    		referenced.objectSubId = 0;
    		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    	}
    
    	/* dependency on extension */
    	recordDependencyOnCurrentExtension(&myself, false);
    
    	/* Post creation hook for new cast */
    	InvokeObjectPostCreateHook(CastRelationId, castid, 0);
    
    	heap_freetuple(tuple);
    
    	heap_close(relation, RowExclusiveLock);
    
    	return castid;
    }
    
    /*
     * get_cast_oid - given two type OIDs, look up a cast OID
     *
     * If missing_ok is false, throw an error if the cast is not found.  If
     * true, just return InvalidOid.
     */
    Oid
    get_cast_oid(Oid sourcetypeid, Oid targettypeid, bool missing_ok)
    {
    	Oid			oid;
    
    	oid = GetSysCacheOid2(CASTSOURCETARGET,
    						  ObjectIdGetDatum(sourcetypeid),
    						  ObjectIdGetDatum(targettypeid));
    	if (!OidIsValid(oid) && !missing_ok)
    		ereport(ERROR,
    				(errcode(ERRCODE_UNDEFINED_OBJECT),
    				 errmsg("cast from type %s to type %s does not exist",
    						format_type_be(sourcetypeid),
    						format_type_be(targettypeid))));
    	return oid;
    }
    
    void
    DropCastById(Oid castOid)
    {
    	Relation	relation;
    	ScanKeyData scankey;
    	SysScanDesc scan;
    	HeapTuple	tuple;
    
    	relation = heap_open(CastRelationId, RowExclusiveLock);
    
    	ScanKeyInit(&scankey,
    				ObjectIdAttributeNumber,
    				BTEqualStrategyNumber, F_OIDEQ,
    				ObjectIdGetDatum(castOid));
    	scan = systable_beginscan(relation, CastOidIndexId, true,
    							  SnapshotNow, 1, &scankey);
    
    	tuple = systable_getnext(scan);
    	if (!HeapTupleIsValid(tuple))
    		elog(ERROR, "could not find tuple for cast %u", castOid);
    	simple_heap_delete(relation, &tuple->t_self);
    
    	systable_endscan(scan);
    	heap_close(relation, RowExclusiveLock);
    }
    
    /*
     * Subroutine for ALTER FUNCTION/AGGREGATE SET SCHEMA/RENAME
     *
     * Is there a function with the given name and signature already in the given
     * namespace?  If so, raise an appropriate error message.
     */
    void
    IsThereFunctionInNamespace(const char *proname, int pronargs,
    						   oidvector proargtypes, Oid nspOid)
    {
    	/* check for duplicate name (more friendly than unique-index failure) */
    	if (SearchSysCacheExists3(PROCNAMEARGSNSP,
    							  CStringGetDatum(proname),
    							  PointerGetDatum(&proargtypes),
    							  ObjectIdGetDatum(nspOid)))
    		ereport(ERROR,
    				(errcode(ERRCODE_DUPLICATE_FUNCTION),
    				 errmsg("function %s already exists in schema \"%s\"",
    						funcname_signature_string(proname, pronargs,
    												  NIL, proargtypes.values),
    						get_namespace_name(nspOid))));
    }
    
    /*
     * ExecuteDoStmt
     *		Execute inline procedural-language code
     */
    void
    ExecuteDoStmt(DoStmt *stmt)
    {
    	InlineCodeBlock *codeblock = makeNode(InlineCodeBlock);
    	ListCell   *arg;
    	DefElem    *as_item = NULL;
    	DefElem    *language_item = NULL;
    	char	   *language;
    	Oid			laninline;
    	HeapTuple	languageTuple;
    	Form_pg_language languageStruct;
    
    	/* Process options we got from gram.y */
    	foreach(arg, stmt->args)
    	{
    		DefElem    *defel = (DefElem *) lfirst(arg);
    
    		if (strcmp(defel->defname, "as") == 0)
    		{
    			if (as_item)
    				ereport(ERROR,
    						(errcode(ERRCODE_SYNTAX_ERROR),
    						 errmsg("conflicting or redundant options")));
    			as_item = defel;
    		}
    		else if (strcmp(defel->defname, "language") == 0)
    		{
    			if (language_item)
    				ereport(ERROR,
    						(errcode(ERRCODE_SYNTAX_ERROR),
    						 errmsg("conflicting or redundant options")));
    			language_item = defel;
    		}
    		else
    			elog(ERROR, "option \"%s\" not recognized",
    				 defel->defname);
    	}
    
    	if (as_item)
    		codeblock->source_text = strVal(as_item->arg);
    	else
    		ereport(ERROR,
    				(errcode(ERRCODE_SYNTAX_ERROR),
    				 errmsg("no inline code specified")));
    
    	/* if LANGUAGE option wasn't specified, use the default */
    	if (language_item)
    		language = strVal(language_item->arg);
    	else
    		language = "plpgsql";
    
    	/* Look up the language and validate permissions */
    	languageTuple = SearchSysCache1(LANGNAME, PointerGetDatum(language));
    	if (!HeapTupleIsValid(languageTuple))
    		ereport(ERROR,
    				(errcode(ERRCODE_UNDEFINED_OBJECT),
    				 errmsg("language \"%s\" does not exist", language),
    				 (PLTemplateExists(language) ?
    				  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));
    
    	codeblock->langOid = HeapTupleGetOid(languageTuple);
    	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
    	codeblock->langIsTrusted = languageStruct->lanpltrusted;
    
    	if (languageStruct->lanpltrusted)
    	{
    		/* if trusted language, need USAGE privilege */
    		AclResult	aclresult;
    
    		aclresult = pg_language_aclcheck(codeblock->langOid, GetUserId(),
    										 ACL_USAGE);
    		if (aclresult != ACLCHECK_OK)
    			aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
    						   NameStr(languageStruct->lanname));
    	}
    	else
    	{
    		/* if untrusted language, must be superuser */
    		if (!superuser())
    			aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
    						   NameStr(languageStruct->lanname));
    	}
    
    	/* get the handler function's OID */
    	laninline = languageStruct->laninline;
    	if (!OidIsValid(laninline))
    		ereport(ERROR,
    				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    			 errmsg("language \"%s\" does not support inline code execution",
    					NameStr(languageStruct->lanname))));
    
    	ReleaseSysCache(languageTuple);
    
    	/* execute the inline handler */
    	OidFunctionCall1(laninline, PointerGetDatum(codeblock));
    }