ruleutils.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,475 行 · 第 1/5 页

						break;
					case FKCONSTR_ACTION_CASCADE:
						string = "CASCADE";
						break;
					case FKCONSTR_ACTION_SETNULL:
						string = "SET NULL";
						break;
					case FKCONSTR_ACTION_SETDEFAULT:
						string = "SET DEFAULT";
						break;
					default:
						elog(ERROR, "unrecognized confdeltype: %d",
							 conForm->confdeltype);
						string = NULL;	/* keep compiler quiet */
						break;
				}
				if (string)
					appendStringInfo(&buf, " ON DELETE %s", string);

				if (conForm->condeferrable)
					appendStringInfo(&buf, " DEFERRABLE");
				if (conForm->condeferred)
					appendStringInfo(&buf, " INITIALLY DEFERRED");

				break;
			}
		case CONSTRAINT_PRIMARY:
		case CONSTRAINT_UNIQUE:
			{
				Datum		val;
				bool		isnull;

				/* Start off the constraint definition */
				if (conForm->contype == CONSTRAINT_PRIMARY)
					appendStringInfo(&buf, "PRIMARY KEY (");
				else
					appendStringInfo(&buf, "UNIQUE (");

				/* Fetch and build target column list */
				val = heap_getattr(tup, Anum_pg_constraint_conkey,
								   RelationGetDescr(conDesc), &isnull);
				if (isnull)
					elog(ERROR, "null conkey for constraint %u",
						 constraintId);

				decompile_column_index_array(val, conForm->conrelid, &buf);

				appendStringInfo(&buf, ")");

				break;
			}
		case CONSTRAINT_CHECK:
			{
				Datum		val;
				bool		isnull;
				char	   *conbin;
				char	   *consrc;
				Node	   *expr;
				List	   *context;

				/* Fetch constraint expression in parsetree form */
				val = heap_getattr(tup, Anum_pg_constraint_conbin,
								   RelationGetDescr(conDesc), &isnull);
				if (isnull)
					elog(ERROR, "null conbin for constraint %u",
						 constraintId);

				conbin = DatumGetCString(DirectFunctionCall1(textout, val));
				expr = stringToNode(conbin);

				/*
				 * If top level is a List, assume it is an implicit-AND
				 * structure, and convert to explicit AND.	This is needed
				 * for partial index predicates.
				 */
				if (expr && IsA(expr, List))
					expr = (Node *) make_ands_explicit((List *) expr);

				/* Set up deparsing context for Var nodes in constraint */
				if (conForm->conrelid != InvalidOid)
				{
					/* relation constraint */
					context = deparse_context_for(get_rel_name(conForm->conrelid),
												  conForm->conrelid);
				}
				else
				{
					/* domain constraint --- can't have Vars */
					context = NIL;
				}

				consrc = deparse_expression_pretty(expr, context, false, false,
												   prettyFlags, 0);

				/*
				 * Now emit the constraint definition.  There are cases where
				 * the constraint expression will be fully parenthesized and
				 * we don't need the outer parens ... but there are other
				 * cases where we do need 'em.  Be conservative for now.
				 *
				 * Note that simply checking for leading '(' and trailing ')'
				 * would NOT be good enough, consider "(x > 0) AND (y > 0)".
				 */
				appendStringInfo(&buf, "CHECK (%s)", consrc);

				break;
			}
		default:
			elog(ERROR, "invalid constraint type \"%c\"", conForm->contype);
			break;
	}

	/* Record the results */
	len = buf.len + VARHDRSZ;
	result = (text *) palloc(len);
	VARATT_SIZEP(result) = len;
	memcpy(VARDATA(result), buf.data, buf.len);

	/* Cleanup */
	pfree(buf.data);
	systable_endscan(conscan);
	heap_close(conDesc, AccessShareLock);

	PG_RETURN_TEXT_P(result);
}


/*
 * Convert an int16[] Datum into a comma-separated list of column names
 * for the indicated relation; append the list to buf.
 */
static void
decompile_column_index_array(Datum column_index_array, Oid relId,
							 StringInfo buf)
{
	Datum	   *keys;
	int			nKeys;
	int			j;

	/* Extract data from array of int16 */
	deconstruct_array(DatumGetArrayTypeP(column_index_array),
					  INT2OID, 2, true, 's',
					  &keys, &nKeys);

	for (j = 0; j < nKeys; j++)
	{
		char	   *colName;

		colName = get_relid_attribute_name(relId, DatumGetInt16(keys[j]));

		if (j == 0)
			appendStringInfo(buf, "%s",
							 quote_identifier(colName));
		else
			appendStringInfo(buf, ", %s",
							 quote_identifier(colName));
	}
}


/* ----------
 * get_expr			- Decompile an expression tree
 *
 * Input: an expression tree in nodeToString form, and a relation OID
 *
 * Output: reverse-listed expression
 *
 * Currently, the expression can only refer to a single relation, namely
 * the one specified by the second parameter.  This is sufficient for
 * partial indexes, column default expressions, etc.
 * ----------
 */
Datum
pg_get_expr(PG_FUNCTION_ARGS)
{
	text	   *expr = PG_GETARG_TEXT_P(0);
	Oid			relid = PG_GETARG_OID(1);
	char	   *relname;

	/* Get the name for the relation */
	relname = get_rel_name(relid);
	if (relname == NULL)
		PG_RETURN_NULL();		/* should we raise an error? */

	return pg_get_expr_worker(expr, relid, relname, 0);
}

Datum
pg_get_expr_ext(PG_FUNCTION_ARGS)
{
	text	   *expr = PG_GETARG_TEXT_P(0);
	Oid			relid = PG_GETARG_OID(1);
	bool		pretty = PG_GETARG_BOOL(2);
	int			prettyFlags;
	char	   *relname;

	prettyFlags = pretty ? PRETTYFLAG_PAREN | PRETTYFLAG_INDENT : 0;

	/* Get the name for the relation */
	relname = get_rel_name(relid);
	if (relname == NULL)
		PG_RETURN_NULL();		/* should we raise an error? */

	return pg_get_expr_worker(expr, relid, relname, prettyFlags);
}

static Datum
pg_get_expr_worker(text *expr, Oid relid, char *relname, int prettyFlags)
{
	text	   *result;
	Node	   *node;
	List	   *context;
	char	   *exprstr;
	char	   *str;

	/* Convert input TEXT object to C string */
	exprstr = DatumGetCString(DirectFunctionCall1(textout,
												  PointerGetDatum(expr)));

	/* Convert expression to node tree */
	node = (Node *) stringToNode(exprstr);

	/*
	 * If top level is a List, assume it is an implicit-AND structure, and
	 * convert to explicit AND.  This is needed for partial index
	 * predicates.
	 */
	if (node && IsA(node, List))
		node = (Node *) make_ands_explicit((List *) node);

	/* Deparse */
	context = deparse_context_for(relname, relid);
	str = deparse_expression_pretty(node, context, false, false,
									prettyFlags, 0);

	/* Pass the result back as TEXT */
	result = DatumGetTextP(DirectFunctionCall1(textin,
											   CStringGetDatum(str)));

	PG_RETURN_TEXT_P(result);
}


/* ----------
 * get_userbyid			- Get a user name by usesysid and
 *				  fallback to 'unknown (UID=n)'
 * ----------
 */
Datum
pg_get_userbyid(PG_FUNCTION_ARGS)
{
	int32		uid = PG_GETARG_INT32(0);
	Name		result;
	HeapTuple	usertup;
	Form_pg_shadow user_rec;

	/*
	 * Allocate space for the result
	 */
	result = (Name) palloc(NAMEDATALEN);
	memset(NameStr(*result), 0, NAMEDATALEN);

	/*
	 * Get the pg_shadow entry and print the result
	 */
	usertup = SearchSysCache(SHADOWSYSID,
							 ObjectIdGetDatum(uid),
							 0, 0, 0);
	if (HeapTupleIsValid(usertup))
	{
		user_rec = (Form_pg_shadow) GETSTRUCT(usertup);
		StrNCpy(NameStr(*result), NameStr(user_rec->usename), NAMEDATALEN);
		ReleaseSysCache(usertup);
	}
	else
		sprintf(NameStr(*result), "unknown (UID=%d)", uid);

	PG_RETURN_NAME(result);
}

/* ----------
 * deparse_expression			- General utility for deparsing expressions
 *
 * calls deparse_expression_pretty with all prettyPrinting disabled
 */
char *
deparse_expression(Node *expr, List *dpcontext,
				   bool forceprefix, bool showimplicit)
{
	return deparse_expression_pretty(expr, dpcontext, forceprefix,
									 showimplicit, 0, 0);
}

/* ----------
 * deparse_expression_pretty	- General utility for deparsing expressions
 *
 * expr is the node tree to be deparsed.  It must be a transformed expression
 * tree (ie, not the raw output of gram.y).
 *
 * dpcontext is a list of deparse_namespace nodes representing the context
 * for interpreting Vars in the node tree.
 *
 * forceprefix is TRUE to force all Vars to be prefixed with their table names.
 *
 * showimplicit is TRUE to force all implicit casts to be shown explicitly.
 *
 * tries to pretty up the output according to prettyFlags and startIndent.
 *
 * The result is a palloc'd string.
 * ----------
 */
static char *
deparse_expression_pretty(Node *expr, List *dpcontext,
						  bool forceprefix, bool showimplicit,
						  int prettyFlags, int startIndent)
{
	StringInfoData buf;
	deparse_context context;

	initStringInfo(&buf);
	context.buf = &buf;
	context.namespaces = dpcontext;
	context.varprefix = forceprefix;
	context.prettyFlags = prettyFlags;
	context.indentLevel = startIndent;

	get_rule_expr(expr, &context, showimplicit);

	return buf.data;
}

/* ----------
 * deparse_context_for			- Build deparse context for a single relation
 *
 * Given the reference name (alias) and OID of a relation, build deparsing
 * context for an expression referencing only that relation (as varno 1,
 * varlevelsup 0).	This is sufficient for many uses of deparse_expression.
 * ----------
 */
List *
deparse_context_for(const char *aliasname, Oid relid)
{
	deparse_namespace *dpns;
	RangeTblEntry *rte;

	dpns = (deparse_namespace *) palloc(sizeof(deparse_namespace));

	/* Build a minimal RTE for the rel */
	rte = makeNode(RangeTblEntry);
	rte->rtekind = RTE_RELATION;
	rte->relid = relid;
	rte->eref = makeAlias(aliasname, NIL);
	rte->inh = false;
	rte->inFromCl = true;

	/* Build one-element rtable */
	dpns->rtable = makeList1(rte);
	dpns->outer_varno = dpns->inner_varno = 0;
	dpns->outer_rte = dpns->inner_rte = NULL;

	/* Return a one-deep namespace stack */
	return makeList1(dpns);
}

/*
 * deparse_context_for_plan		- Build deparse context for a plan node
 *
 * We assume we are dealing with an upper-level plan node having either
 * one or two referenceable children (pass innercontext = NULL if only one).
 * The passed-in Nodes should be made using deparse_context_for_subplan
 * and/or deparse_context_for_relation.  The resulting context will work
 * for deparsing quals, tlists, etc of the plan node.
 *
 * An rtable list can also be passed in case plain Vars might be seen.
 * This is not needed for true upper-level expressions, but is helpful for
 * Sort nodes and similar cases with slightly bogus targetlists.
 */
List *
deparse_context_for_plan(int outer_varno, Node *outercontext,
						 int inner_varno, Node *innercontext,
						 List *rtable)
{
	deparse_namespace *dpns;

	dpns = (deparse_namespace *) palloc(sizeof(deparse_namespace));

	dpns->rtable = rtable;
	dpns->outer_varno = outer_varno;
	dpns->outer_rte = (RangeTblEntry *) outercontext;
	dpns->inner_varno = inner_varno;
	dpns->inner_rte = (RangeTblEntry *) innercontext;

	/* Return a one-deep namespace stack */
	return makeList1(dpns);
}

/*
 * deparse_context_for_rte		- Build deparse context for 1 relation
 *
 * Helper routine to build one of the inputs for deparse_context_for_plan.
 *
 * The returned node is actually the given RangeTblEntry, but we declare it
 * as just Node to discourage callers from assuming anything.
 */
Node *
deparse_context_for_rte(RangeTblEntry *rte)
{
	return (Node *) rte;
}

/*
 * deparse_context_for_subplan	- Build deparse context for a plan node
 *
 * Helper routine to build one of the inputs for deparse_context_for_plan.
 * Pass the tlist of the subplan node, plus the query rangetable.
 *
 * The returned node is actually a RangeTblEntry, but we declare it as just
 * Node to discourage callers from assuming anything.
 */
Node *
deparse_context_for_subplan(const char *name, List *tlist,
							List *rtable)
{
	RangeTblEntry *rte = makeNode(RangeTblEntry);
	List	   *attrs = NIL;
	int			nattrs = 0;
	int			rtablelength = length(rtable);
	List	   *tl;
	char		buf[32];

	foreach(tl, tlist)
	{
		TargetEntry *tle = lfirst(tl);
		Resdom	   *resdom = tle->resdom;

		nattrs++;
		Assert(resdom->resno == nattrs);
		if (resdom->resname)
		{
			attrs = lappend(attrs, makeString(resdom->resname));
			continue;
		}
		if (tle->expr && IsA(tle->expr, Var))
		{
			Var		   *var = (Var *) tle->expr;

			/* varno/varattno won't be any good, but varnoold might be */
			if (var->varnoold > 0 && var->varnoold <= rtablelength)
			{
				RangeTblEntry *varrte = rt_fetch(var->varnoold, rtable);
				char	   *varname;

				varname = get_rte_attribute_name(varrte, var->varoattno);
				attrs = lappend(attrs, makeString(varname));
				continue;
			}
		}
		/* Fallback if can't get name */
		snprintf(buf, sizeof(buf), "?column%d?", resdom->resno);
		attrs = lappend(attrs, makeString(pstrdup(buf)));
	}

	rte->rtekind = RTE_SPECIAL; /* XXX */
	rte->relid = InvalidOid;
	rte->eref = makeAlias(name, attrs);
	rte->inh = false;
	rte->inFromCl = true;

	return (Node *) rte;
}

/* ----------
 * make_ruledef			- reconstruct the CREATE RULE command
 *				  for a given pg_rewrite tuple
 * ----------
 */
static void
make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
			 int prettyFlags)
{
	char	   *rulename;
	char		ev_type;
	Oid			ev_class;
	int2		ev_attr;
	bool		is_instead;
	char	   *ev_qual;
	char	   *ev_action;
	List	   *actions = NIL;
	int			fno;
	Datum		dat;
	bool		isnull;

	/*
	 * Get the attribute values from the rules tuple
	 */