Fix incorrect Assert; install a more trustworthy check on whether

ALTER COLUMN SET STORAGE should be allowed.

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 84e1ae40a5e218ade058335f5b306f997ce49e65..49170afd5cb1bed1862fcaa44c55daa868d06d62 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.5 2002/04/19 23:13:54 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.6 2002/04/22 21:46:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -771,10 +771,10 @@ AlterTableAlterColumnFlags(Oid myrelid,
 {
    Relation    rel;
    int         newtarget = 1;
-   char        newstorage = 'x';
-   char        *storagemode;
+   char        newstorage = 'p';
    Relation    attrelation;
    HeapTuple   tuple;
+   Form_pg_attribute attrtuple;
 
    rel = heap_open(myrelid, AccessExclusiveLock);
 
@@ -813,9 +813,11 @@ AlterTableAlterColumnFlags(Oid myrelid,
    else if (*flagType == 'M')
    {
        /* STORAGE */
-       Assert(IsA(flagValue, Value));
+       char        *storagemode;
 
+       Assert(IsA(flagValue, String));
        storagemode = strVal(flagValue);
+
        if (strcasecmp(storagemode, "plain") == 0)
            newstorage = 'p';
        else if (strcasecmp(storagemode, "external") == 0)
@@ -872,26 +874,30 @@ AlterTableAlterColumnFlags(Oid myrelid,
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "ALTER TABLE: relation \"%s\" has no column \"%s\"",
             RelationGetRelationName(rel), colName);
+   attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);
 
-   if (((Form_pg_attribute) GETSTRUCT(tuple))->attnum < 0)
+   if (attrtuple->attnum < 0)
        elog(ERROR, "ALTER TABLE: cannot change system attribute \"%s\"",
             colName);
    /*
     * Now change the appropriate field
     */
    if (*flagType == 'S')
-       ((Form_pg_attribute) GETSTRUCT(tuple))->attstattarget = newtarget;
-   else
+       attrtuple->attstattarget = newtarget;
+   else if (*flagType == 'M')
    {
-       if ((newstorage == 'p') ||
-           (((Form_pg_attribute) GETSTRUCT(tuple))->attlen == -1))
-           ((Form_pg_attribute) GETSTRUCT(tuple))->attstorage = newstorage;
+       /*
+        * safety check: do not allow toasted storage modes unless column
+        * datatype is TOAST-aware.  We assume the datatype's typstorage
+        * will be 'p' if and only if it ain't TOAST-aware.
+        */
+       if (newstorage == 'p' || get_typstorage(attrtuple->atttypid) != 'p')
+           attrtuple->attstorage = newstorage;
        else
-       {
-           elog(ERROR,
-                "ALTER TABLE: Fixed-length columns can only have storage \"plain\"");
-       }
+           elog(ERROR, "ALTER TABLE: Column datatype %s can only have storage \"plain\"",
+                format_type_be(attrtuple->atttypid));
    }
+
    simple_heap_update(attrelation, &tuple->t_self, tuple);
 
    /* keep system catalog indices current */