ruleutils.c

来自「postgresql8.3.4源码,开源数据库」· C语言 代码 · 共 2,446 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 confupdtype: %d",
							 conForm->confupdtype);
						string = NULL;	/* keep compiler quiet */
						break;
				}
				if (string)
					appendStringInfo(&buf, " ON UPDATE %s", string);

				switch (conForm->confdeltype)
				{
					case FKCONSTR_ACTION_NOACTION:
						string = NULL;	/* suppress default */
						break;
					case FKCONSTR_ACTION_RESTRICT:
						string = "RESTRICT";
						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;
				Oid			indexId;

				/* 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 = SysCacheGetAttr(CONSTROID, tup,
									  Anum_pg_constraint_conkey, &isnull);
				if (isnull)
					elog(ERROR, "null conkey for constraint %u",
						 constraintId);

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

				appendStringInfo(&buf, ")");

				indexId = get_constraint_index(constraintId);

				/* XXX why do we only print these bits if fullCommand? */
				if (fullCommand && OidIsValid(indexId))
				{
					char	   *options = flatten_reloptions(indexId);
					Oid			tblspc;

					if (options)
					{
						appendStringInfo(&buf, " WITH (%s)", options);
						pfree(options);
					}

					tblspc = get_rel_tablespace(indexId);
					if (OidIsValid(tblspc))
						appendStringInfo(&buf, " USING INDEX TABLESPACE %s",
							  quote_identifier(get_tablespace_name(tblspc)));
				}

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

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

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

				/* 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;
	}

	/* Cleanup */
	ReleaseSysCache(tup);

	return buf.data;
}


/*
 * 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, NULL, &nKeys);

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

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

		if (j == 0)
			appendStringInfoString(buf, 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? */

	PG_RETURN_TEXT_P(string_to_text(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? */

	PG_RETURN_TEXT_P(string_to_text(pg_get_expr_worker(expr, relid, relname, prettyFlags)));
}

static char *
pg_get_expr_worker(text *expr, Oid relid, char *relname, int prettyFlags)
{
	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);

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

	return str;
}


/* ----------
 * get_userbyid			- Get a user name by roleid and
 *				  fallback to 'unknown (OID=n)'
 * ----------
 */
Datum
pg_get_userbyid(PG_FUNCTION_ARGS)
{
	Oid			roleid = PG_GETARG_OID(0);
	Name		result;
	HeapTuple	roletup;
	Form_pg_authid role_rec;

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

	/*
	 * Get the pg_authid entry and print the result
	 */
	roletup = SearchSysCache(AUTHOID,
							 ObjectIdGetDatum(roleid),
							 0, 0, 0);
	if (HeapTupleIsValid(roletup))
	{
		role_rec = (Form_pg_authid) GETSTRUCT(roletup);
		StrNCpy(NameStr(*result), NameStr(role_rec->rolname), NAMEDATALEN);
		ReleaseSysCache(roletup);
	}
	else
		sprintf(NameStr(*result), "unknown (OID=%u)", roleid);

	PG_RETURN_NAME(result);
}


/*
 * pg_get_serial_sequence
 *		Get the name of the sequence used by a serial column,
 *		formatted suitably for passing to setval, nextval or currval.
 *		First parameter is not treated as double-quoted, second parameter
 *		is --- see documentation for reason.
 */
Datum
pg_get_serial_sequence(PG_FUNCTION_ARGS)
{
	text	   *tablename = PG_GETARG_TEXT_P(0);
	text	   *columnname = PG_GETARG_TEXT_P(1);
	RangeVar   *tablerv;
	Oid			tableOid;
	char	   *column;
	AttrNumber	attnum;
	Oid			sequenceId = InvalidOid;
	Relation	depRel;
	ScanKeyData key[3];
	SysScanDesc scan;
	HeapTuple	tup;

	/* Get the OID of the table */
	tablerv = makeRangeVarFromNameList(textToQualifiedNameList(tablename));
	tableOid = RangeVarGetRelid(tablerv, false);

	/* Get the number of the column */
	column = DatumGetCString(DirectFunctionCall1(textout,
											   PointerGetDatum(columnname)));

	attnum = get_attnum(tableOid, column);
	if (attnum == InvalidAttrNumber)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_COLUMN),
				 errmsg("column \"%s\" of relation \"%s\" does not exist",
						column, tablerv->relname)));

	/* Search the dependency table for the dependent sequence */
	depRel = heap_open(DependRelationId, AccessShareLock);

	ScanKeyInit(&key[0],
				Anum_pg_depend_refclassid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(RelationRelationId));
	ScanKeyInit(&key[1],
				Anum_pg_depend_refobjid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(tableOid));
	ScanKeyInit(&key[2],
				Anum_pg_depend_refobjsubid,
				BTEqualStrategyNumber, F_INT4EQ,
				Int32GetDatum(attnum));

	scan = systable_beginscan(depRel, DependReferenceIndexId, true,
							  SnapshotNow, 3, key);

	while (HeapTupleIsValid(tup = systable_getnext(scan)))
	{
		Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(tup);

		/*
		 * We assume any auto dependency of a sequence on a column must be
		 * what we are looking for.  (We need the relkind test because indexes
		 * can also have auto dependencies on columns.)
		 */
		if (deprec->classid == RelationRelationId &&
			deprec->objsubid == 0 &&
			deprec->deptype == DEPENDENCY_AUTO &&
			get_rel_relkind(deprec->objid) == RELKIND_SEQUENCE)
		{
			sequenceId = deprec->objid;
			break;
		}
	}

	systable_endscan(scan);
	heap_close(depRel, AccessShareLock);

	if (OidIsValid(sequenceId))
	{
		HeapTuple	classtup;
		Form_pg_class classtuple;
		char	   *nspname;
		char	   *result;

		/* Get the sequence's pg_class entry */
		classtup = SearchSysCache(RELOID,
								  ObjectIdGetDatum(sequenceId),
								  0, 0, 0);
		if (!HeapTupleIsValid(classtup))
			elog(ERROR, "cache lookup failed for relation %u", sequenceId);
		classtuple = (Form_pg_class) GETSTRUCT(classtup);

		/* Get the namespace */
		nspname = get_namespace_name(classtuple->relnamespace);
		if (!nspname)
			elog(ERROR, "cache lookup failed for namespace %u",
				 classtuple->relnamespace);

		/* And construct the result string */
		result = quote_qualified_identifier(nspname,
											NameStr(classtuple->relname));

		ReleaseSysCache(classtup);

		PG_RETURN_TEXT_P(string_to_text(result));
	}

	PG_RETURN_NULL();
}


/*
 * 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 = list_make1(rte);
	dpns->outer_plan = dpns->inner_plan = NULL;

	/* Return a one-deep namespace stack */
	return list_make1(dpns);