On Sun, 2004-11-14 at 18:29 -0500, Tom Lane wrote:
> Good analysis. We can't check earlier than DefineRelation AFAICS,
> because earlier stages don't know about inherited columns.
>
> On reflection I suspect there are similar issues with SELECTs that have
> more than 64K output columns. This probably has to be guarded against
> in parser/analyze.c.
You're correct -- we also crash on extremely long SELECT statements.
Another variant of the problem would be a CREATE TABLE that inherits
from, say, 70 relations, each of which has 1,000 columns.
Attached is a patch. Not entirely sure that the checks I added are in
the right places, but at any rate this fixes the three identified
problems for me.
-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/parse_target.c
+++ src/backend/parser/parse_target.c
@@ -106,6 +106,17 @@
List *p_target = NIL;
ListCell *o_target;
+ /*
+ * Reject tlists that are too long. Ultimately there is a
+ * correspondence between tlist entries and attributes in a tuple,
+ * so use MaxHeapAttributeNumber.
+ */
+ if (list_length(targetlist) > MaxHeapAttributeNumber)
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("target lists can have at most %d entries",
+ MaxHeapAttributeNumber)));
+
foreach(o_target, targetlist)
{
ResTarget *res = (ResTarget *) lfirst(o_target);
---------------------------(end of broadcast)---------------------------
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