On Mon, 2004-11-15 at 20:53 -0500, Tom Lane wrote:
> I think the SELECT limit should be MaxTupleAttributeNumber not
> MaxHeapAttributeNumber.
Ah, true -- I forgot about the distinction...
> What I think needs to happen is to check p_next_resno at some point
> after the complete tlist has been built.
Attached is a revised patch -- I just did the check at the end of
transformStmt(), since otherwise we'll need to duplicate code in the
various places that resnos are used/incremented (set operation
statements, normal selects, updates, and so on). This is somewhat
fragile in that we usually assign p_next_resno to an AttrNumber and only
check for overflow at the end of the analysis phase, but it seems safe
for the moment...
BTW I figure this should be backpatched to REL7_4_STABLE. Barring any
objections I will do that (and apply to HEAD) this evening.
-Neil
--- src/backend/commands/tablecmds.c
+++ src/backend/commands/tablecmds.c
@@ -681,6 +681,23 @@
int child_attno;
/*
+ * Check for and reject tables with too many columns. We perform
+ * this check relatively early for two reasons: (a) we don't run
+ * the risk of overflowing an AttrNumber in subsequent code (b) an
+ * O(n^2) algorithm is okay if we're processing <= 1600 columns,
+ * but could take minutes to execute if the user attempts to
+ * create a table with hundreds of thousands of columns.
+ *
+ * Note that we also need to check that any we do not exceed this
+ * figure after including columns from inherited relations.
+ */
+ if (list_length(schema) > MaxHeapAttributeNumber)
+ ereport(ERROR,
+ (errcode(ERRCODE_TOO_MANY_COLUMNS),
+ errmsg("tables can have at most %d columns",
+ MaxHeapAttributeNumber)));
+
+ /*
* Check for duplicate names in the explicit list of attributes.
*
* Although we might consider merging such entries in the same way that
@@ -979,6 +996,16 @@
}
schema = inhSchema;
+
+ /*
+ * Check that we haven't exceeded the legal # of columns after
+ * merging in inherited columns.
+ */
+ if (list_length(schema) > MaxHeapAttributeNumber)
+ ereport(ERROR,
+ (errcode(ERRCODE_TOO_MANY_COLUMNS),
+ errmsg("tables can have at most %d columns",
+ MaxHeapAttributeNumber)));
}
/*
--- src/backend/parser/analyze.c
+++ src/backend/parser/analyze.c
@@ -396,6 +396,18 @@
result->querySource = QSRC_ORIGINAL;
result->canSetTag = true;
+ /*
+ * Check that we did not produce too many resnos; at the very
+ * least we cannot allow more than 2^16, since that would exceed
+ * the range of a AttrNumber. It seems safest to use
+ * MaxTupleAttributeNumber.
+ */
+ if (pstate->p_next_resno - 1 > MaxTupleAttributeNumber)
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("target lists can have at most %d entries",
+ MaxTupleAttributeNumber)));
+
return result;
}
---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
