tablecmds.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,338 行 · 第 1/5 页

	{
		ScanKeyEntryInitialize(&skey[0], 0x0,
							   Anum_pg_trigger_tgrelid,
							   F_OIDEQ,
							   ObjectIdGetDatum(relid));
		trigscan = systable_beginscan(tgrel, TriggerRelidNameIndex,
									  true, SnapshotNow,
									  1, skey);
	}

	while ((tuple = systable_getnext(trigscan)) != NULL)
	{
		Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple);
		bytea	   *val;
		bytea	   *newtgargs;
		bool		isnull;
		int			tg_type;
		bool		examine_pk;
		bool		changed;
		int			tgnargs;
		int			i;
		int			newlen;
		const char *arga[RI_MAX_ARGUMENTS];
		const char *argp;

		tg_type = ri_trigger_type(pg_trigger->tgfoid);
		if (tg_type == RI_TRIGGER_NONE)
		{
			/* Not an RI trigger, forget it */
			continue;
		}

		/*
		 * It is an RI trigger, so parse the tgargs bytea.
		 *
		 * NB: we assume the field will never be compressed or moved out of
		 * line; so does trigger.c ...
		 */
		tgnargs = pg_trigger->tgnargs;
		val = (bytea *) fastgetattr(tuple,
									Anum_pg_trigger_tgargs,
									tgrel->rd_att, &isnull);
		if (isnull || tgnargs < RI_FIRST_ATTNAME_ARGNO ||
			tgnargs > RI_MAX_ARGUMENTS)
		{
			/* This probably shouldn't happen, but ignore busted triggers */
			continue;
		}
		argp = (const char *) VARDATA(val);
		for (i = 0; i < tgnargs; i++)
		{
			arga[i] = argp;
			argp += strlen(argp) + 1;
		}

		/*
		 * Figure out which item(s) to look at.  If the trigger is
		 * primary-key type and attached to my rel, I should look at the
		 * PK fields; if it is foreign-key type and attached to my rel, I
		 * should look at the FK fields.  But the opposite rule holds when
		 * examining triggers found by tgconstrrel search.
		 */
		examine_pk = (tg_type == RI_TRIGGER_PK) == (!fk_scan);

		changed = false;
		if (update_relname)
		{
			/* Change the relname if needed */
			i = examine_pk ? RI_PK_RELNAME_ARGNO : RI_FK_RELNAME_ARGNO;
			if (strcmp(arga[i], oldname) == 0)
			{
				arga[i] = newname;
				changed = true;
			}
		}
		else
		{
			/* Change attname(s) if needed */
			i = examine_pk ? RI_FIRST_ATTNAME_ARGNO + RI_KEYPAIR_PK_IDX :
				RI_FIRST_ATTNAME_ARGNO + RI_KEYPAIR_FK_IDX;
			for (; i < tgnargs; i += 2)
			{
				if (strcmp(arga[i], oldname) == 0)
				{
					arga[i] = newname;
					changed = true;
				}
			}
		}

		if (!changed)
		{
			/* Don't need to update this tuple */
			continue;
		}

		/*
		 * Construct modified tgargs bytea.
		 */
		newlen = VARHDRSZ;
		for (i = 0; i < tgnargs; i++)
			newlen += strlen(arga[i]) + 1;
		newtgargs = (bytea *) palloc(newlen);
		VARATT_SIZEP(newtgargs) = newlen;
		newlen = VARHDRSZ;
		for (i = 0; i < tgnargs; i++)
		{
			strcpy(((char *) newtgargs) + newlen, arga[i]);
			newlen += strlen(arga[i]) + 1;
		}

		/*
		 * Build modified tuple.
		 */
		for (i = 0; i < Natts_pg_trigger; i++)
		{
			values[i] = (Datum) 0;
			replaces[i] = ' ';
			nulls[i] = ' ';
		}
		values[Anum_pg_trigger_tgargs - 1] = PointerGetDatum(newtgargs);
		replaces[Anum_pg_trigger_tgargs - 1] = 'r';

		tuple = heap_modifytuple(tuple, tgrel, values, nulls, replaces);

		/*
		 * Update pg_trigger and its indexes
		 */
		simple_heap_update(tgrel, &tuple->t_self, tuple);

		CatalogUpdateIndexes(tgrel, tuple);

		/*
		 * Invalidate trigger's relation's relcache entry so that other
		 * backends (and this one too!) are sent SI message to make them
		 * rebuild relcache entries.  (Ideally this should happen
		 * automatically...)
		 *
		 * We can skip this for triggers on relid itself, since that
		 * relcache flush will happen anyway due to the table or column
		 * rename.  We just need to catch the far ends of RI relationships.
		 */
		pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple);
		if (pg_trigger->tgrelid != relid)
			CacheInvalidateRelcache(pg_trigger->tgrelid);

		/* free up our scratch memory */
		pfree(newtgargs);
		heap_freetuple(tuple);
	}

	systable_endscan(trigscan);

	heap_close(tgrel, RowExclusiveLock);

	/*
	 * Increment cmd counter to make updates visible; this is needed in
	 * case the same tuple has to be updated again by next pass (can
	 * happen in case of a self-referential FK relationship).
	 */
	CommandCounterIncrement();
}


/* ----------------
 *		AlterTableAddColumn
 *		(formerly known as PerformAddAttribute)
 *
 *		adds an additional attribute to a relation
 * ----------------
 */
void
AlterTableAddColumn(Oid myrelid,
					bool recurse,
					ColumnDef *colDef)
{
	Relation	rel,
				pgclass,
				attrdesc;
	HeapTuple	reltup;
	HeapTuple	newreltup;
	HeapTuple	attributeTuple;
	Form_pg_attribute attribute;
	FormData_pg_attribute attributeD;
	int			i;
	int			minattnum,
				maxatts;
	HeapTuple	typeTuple;
	Form_pg_type tform;
	int			attndims;
	ObjectAddress myself,
				referenced;

	/*
	 * Grab an exclusive lock on the target table, which we will NOT
	 * release until end of transaction.
	 */
	rel = heap_open(myrelid, AccessExclusiveLock);

	if (rel->rd_rel->relkind != RELKIND_RELATION)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("\"%s\" is not a table",
						RelationGetRelationName(rel))));

	/*
	 * permissions checking.  this would normally be done in utility.c,
	 * but this particular routine is recursive.
	 *
	 * normally, only the owner of a class can change its schema.
	 */
	if (!pg_class_ownercheck(myrelid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
					   RelationGetRelationName(rel));

	if (!allowSystemTableMods && IsSystemRelation(rel))
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
				 errmsg("permission denied: \"%s\" is a system catalog",
						RelationGetRelationName(rel))));

	/*
	 * Recurse to add the column to child classes, if requested.
	 *
	 * any permissions or problems with duplicate attributes will cause the
	 * whole transaction to abort, which is what we want -- all or
	 * nothing.
	 */
	if (recurse)
	{
		List	   *child,
				   *children;
		ColumnDef  *colDefChild = copyObject(colDef);

		/* Child should see column as singly inherited */
		colDefChild->inhcount = 1;
		colDefChild->is_local = false;

		/* We only want direct inheritors */
		children = find_inheritance_children(myrelid);

		foreach(child, children)
		{
			Oid			childrelid = lfirsto(child);
			HeapTuple	tuple;
			Form_pg_attribute childatt;
			Relation	childrel;

			if (childrelid == myrelid)
				continue;

			childrel = heap_open(childrelid, AccessExclusiveLock);

			/* Does child already have a column by this name? */
			attrdesc = heap_openr(AttributeRelationName, RowExclusiveLock);
			tuple = SearchSysCacheCopyAttName(childrelid, colDef->colname);
			if (!HeapTupleIsValid(tuple))
			{
				/* No, recurse to add it normally */
				heap_close(attrdesc, RowExclusiveLock);
				heap_close(childrel, NoLock);
				AlterTableAddColumn(childrelid, true, colDefChild);
				continue;
			}
			childatt = (Form_pg_attribute) GETSTRUCT(tuple);

			/* Okay if child matches by type */
			if (typenameTypeId(colDef->typename) != childatt->atttypid ||
				colDef->typename->typmod != childatt->atttypmod)
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("child table \"%s\" has different type for column \"%s\"",
							get_rel_name(childrelid), colDef->colname)));

			/*
			 * XXX if we supported NOT NULL or defaults, would need to do
			 * more work here to verify child matches
			 */
			ereport(NOTICE,
					(errmsg("merging definition of column \"%s\" for child \"%s\"",
							colDef->colname, get_rel_name(childrelid))));

			/* Bump the existing child att's inhcount */
			childatt->attinhcount++;
			simple_heap_update(attrdesc, &tuple->t_self, tuple);
			CatalogUpdateIndexes(attrdesc, tuple);

			/*
			 * Propagate any new CHECK constraints into the child table
			 * and its descendants
			 */
			if (colDef->constraints != NIL)
			{
				CommandCounterIncrement();
				AlterTableAddConstraint(childrelid, true, colDef->constraints);
			}

			heap_freetuple(tuple);
			heap_close(attrdesc, RowExclusiveLock);
			heap_close(childrel, NoLock);
		}
	}
	else
	{
		/*
		 * If we are told not to recurse, there had better not be any
		 * child tables; else the addition would put them out of step.
		 */
		if (find_inheritance_children(myrelid) != NIL)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
				 errmsg("column must be added to child tables too")));
	}

	/*
	 * OK, get on with it...
	 *
	 * Implementation restrictions: because we don't touch the table rows,
	 * the new column values will initially appear to be NULLs.  (This
	 * happens because the heap tuple access routines always check for
	 * attnum > # of attributes in tuple, and return NULL if so.)
	 * Therefore we can't support a DEFAULT value in SQL92-compliant
	 * fashion, and we also can't allow a NOT NULL constraint.
	 *
	 * We do allow CHECK constraints, even though these theoretically could
	 * fail for NULL rows (eg, CHECK (newcol IS NOT NULL)).
	 */
	if (colDef->raw_default || colDef->cooked_default)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
			   errmsg("adding columns with defaults is not implemented"),
		  errhint("Add the column, then use ALTER TABLE SET DEFAULT.")));

	if (colDef->is_not_null)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("adding NOT NULL columns is not implemented"),
		 errhint("Add the column, then use ALTER TABLE SET NOT NULL.")));

	pgclass = heap_openr(RelationRelationName, RowExclusiveLock);

	reltup = SearchSysCache(RELOID,
							ObjectIdGetDatum(myrelid),
							0, 0, 0);
	if (!HeapTupleIsValid(reltup))
		elog(ERROR, "cache lookup failed for relation %u", myrelid);

	/*
	 * this test is deliberately not attisdropped-aware, since if one
	 * tries to add a column matching a dropped column name, it's gonna
	 * fail anyway.
	 */
	if (SearchSysCacheExists(ATTNAME,
							 ObjectIdGetDatum(myrelid),
							 PointerGetDatum(colDef->colname),
							 0, 0))
		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_COLUMN),
			 errmsg("column \"%s\" of relation \"%s\" already exists",
					colDef->colname, RelationGetRelationName(rel))));

	minattnum = ((Form_pg_class) GETSTRUCT(reltup))->relnatts;
	maxatts = minattnum + 1;
	if (maxatts > MaxHeapAttributeNumber)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_COLUMNS),
				 errmsg("tables can have at most %d columns",
						MaxHeapAttributeNumber)));
	i = minattnum + 1;

	attrdesc = heap_openr(AttributeRelationName, RowExclusiveLock);

	if (colDef->typename->arrayBounds)
		attndims = length(colDef->typename->arrayBounds);
	else
		attndims = 0;

	typeTuple = typenameType(colDef->typename);
	tform = (Form_pg_type) GETSTRUCT(typeTuple);

	/* make sure datatype is legal for a column */
	CheckAttributeType(colDef->colname, HeapTupleGetOid(typeTuple));

	attributeTuple = heap_addheader(Natts_pg_attribute,
									false,
									ATTRIBUTE_TUPLE_SIZE,
									(void *) &attributeD);

	attribute = (Form_pg_attribute) GETSTRUCT(attributeTuple);

	attribute->attrelid = myrelid;
	namestrcpy(&(attribute->attname), colDef->colname);
	attribute->atttypid = HeapTupleGetOid(typeTuple);
	attribute->attstattarget = -1;
	attribute->attlen = tform->typlen;
	attribute->attcacheoff = -1;
	attribute->atttypmod = colDef->typename->typmod;
	attribute->attnum = i;
	attribute->attbyval = tform->typbyval;
	attribute->attndims = attndims;
	attribute->attisset = (bool) (tform->typtype == 'c');
	attribute->attstorage = tform->typstorage;
	attribute->attalign = tform->typalign;
	attribute->attnotnull = colDef->is_not_null;
	attribute->atthasdef = (colDef->raw_default != NULL ||
							colDef->cooked_default != NULL);
	attribute->attisdropped = false;
	attribute->attislocal = colDef->is_local;
	attribute->attinhcount = colDef->inhcount;

	ReleaseSysCache(typeTuple);

	simple_heap_insert(attrdesc, attributeTuple);

	/* Update indexes on pg_attribute */
	CatalogUpdateIndexes(attrdesc, attributeTuple);

	heap_close(attrdesc, RowExclusiveLock);

	/*
	 * Update number of attributes in pg_class tuple
	 */
	newreltup = heap_copytuple(reltup);

	((Form_pg_class) GETSTRUCT(newreltup))->relnatts = maxatts;

	simple_heap_update(pgclass, &newreltup->t_self, newreltup);

	/* keep catalog indexes current */
	CatalogUpdateIndexes(pgclass, newreltup);

	heap_freetuple(newreltup);
	ReleaseSysCache(reltup);

	heap_close(pgclass, RowExclusiveLock);

	heap_close(rel, NoLock);	/* close rel but keep lock! */

	/*
	 * Add datatype dependency for the new column.
	 */
	myself.classId = RelOid_pg_class;
	myself.objectId = myrelid;
	myself.objectSubId = i;
	referenced.classId = RelOid_pg_type;
	referenced.objectId = attribute->atttypid;
	referenced.objectSubId = 0;
	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

	/*
	 * Make our catalog updates visible for subsequent steps.
	 */
	CommandCounterIncrement();

	/*
	 * Add any CHECK constraints attached to the new column.
	 *
	 * To do this we must re-open the rel so that its new attr list gets
	 * loaded into the relcache.
	 */
	if (colDef->constraints != NIL)
	{
		rel = heap_open(myrelid, AccessExclusiveLock);
		AddRelationRawConstraints(rel, NIL, colDef->constraints);
		heap_close(rel, NoLock);
	}

	/*