This patch for Versions 1 and 2 corrects the following bug:

In a catalog class that has a "name" type attribute, UPDATEing of an
instance of that class may destroy all of the attributes of that
instance that are stored as or after the "name" attribute.

This is caused by the alignment value of the "name" type being set to
"double" in Class pg_type, but "integer" in Class pg_attribute.
Postgres constructs a tuple using double alignment, but interprets it
using integer alignment.

The fix is to change the alignment to integer in pg_type.

Note that this corrects the problem for new Postgres systems.  Existing
databases already contain the error and it can't easily be repaired because
this very bug prevents updating the class that contains it.

--
Bryan Henderson                                    Phone 408-227-6803
San Jose, California

diff --git a/src/backend/catalog/pg_attribute.h b/src/backend/catalog/pg_attribute.h
index 0888ee2d7ff3b4bb050bcc1a30a3e3734d7b97fa..ab2d625f3ef2549c8d47b573a8b5f6fc50b921ba 100644 (file)
--- a/src/backend/catalog/pg_attribute.h
+++ b/src/backend/catalog/pg_attribute.h
@@ -7,7 +7,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: pg_attribute.h,v 1.1.1.1.2.1 1996/08/21 04:23:32 scrappy Exp $
+ * $Id: pg_attribute.h,v 1.1.1.1.2.2 1996/08/24 20:56:42 scrappy Exp $
  *
  * NOTES
  *    the genbki.sh script reads this file and generates .bki
@@ -44,13 +44,19 @@ CATALOG(pg_attribute) BOOTSTRAP {
     Oid        attrelid;      
     NameData   attname;
     Oid        atttypid;
+      /* atttypid is the OID of the instance in Catalog Class pg_type that
+         defines the data type of this attribute (e.g. int4).  Information in
+         that instance is redundant with the attlen, attbyval, and attalign
+         attributes of this instance, so they had better match or Postgres
+         will fail.
+         */
     Oid        attdefrel;
     int4       attnvals;
     Oid        atttyparg;      /* type arg for arrays/spquel/procs */
     int2       attlen;
-      /* attlen is the number of bytes we use to represent the value 
-         of this attribute, e.g. 4 for an int4.  But for a variable length 
-         attribute, attlen is -1.
+      /* attlen is a copy of the typlen field from pg_type for this
+         attribute.  See atttypid above.  See struct TypeTupleFormData for
+         definition.
          */
     int2       attnum;
       /* attnum is the "attribute number" for the attribute:  A 
@@ -68,6 +74,10 @@ CATALOG(pg_attribute) BOOTSTRAP {
          */
     int2       attbound;
     bool       attbyval;
+      /* attbyval is a copy of the typbyval field from pg_type for this
+         attribute.  See atttypid above.  See struct TypeTupleFormData for
+         definition.
+         */
     bool       attcanindex;
     Oid        attproc;        /* spquel? */
     int4       attnelems;
@@ -80,7 +90,11 @@ CATALOG(pg_attribute) BOOTSTRAP {
          walking process.  
          */
     bool        attisset;
-    char       attalign;  /* alignment (c=char, s=short, i=int, d=double) */
+    char       attalign; 
+      /* attalign is a copy of the typalign field from pg_type for this
+         attribute.  See atttypid above.  See struct TypeTupleFormData for
+         definition.
+         */
 } FormData_pg_attribute;
 
 /*