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Make equalTupleDescs() compare attlen/attbyval/attalign rather than

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assuming comparison of atttypid is sufficient.  In a dropped column
atttypid will be 0, and we'd better check the physical-storage data
to make sure the tupdescs are physically compatible.
I do not believe there is a real risk before 8.0, since before that
we only used this routine to compare successive states of the tupdesc
for a particular relation.  But 8.0's typcache.c might be comparing
arbitrary tupdescs so we'd better play it safer.
This commit is contained in:
Tom Lane 2005-04-14 22:34:48 +00:00
parent 0453a997af
commit 8e14408028
1 changed files with 16 additions and 5 deletions
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21
src/backend/access/common/tupdesc.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/common/tupdesc.c,v 1.110 2005/03/31 22:46:04 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/common/tupdesc.c,v 1.111 2005/04/14 22:34:48 tgl Exp $
*
* NOTES
* some of the executor utility code such as "ExecTypeFromTL" should be
@ -274,10 +274,15 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
/*
* We do not need to check every single field here: we can
* disregard attrelid, attnum (it was used to place the row in the
* attrs array) and everything derived from the column datatype.
* Also, attcacheoff must NOT be checked since it's possibly not
* set in both copies.
* disregard attrelid and attnum (which were used to place the row
* in the attrs array in the first place). It might look like we
* could dispense with checking attlen/attbyval/attalign, since these
* are derived from atttypid; but in the case of dropped columns
* we must check them (since atttypid will be zero for all dropped
* columns) and in general it seems safer to check them always.
*
* attcacheoff must NOT be checked since it's possibly not set
* in both copies.
*/
if (strcmp(NameStr(attr1->attname), NameStr(attr2->attname)) != 0)
return false;
@ -285,12 +290,18 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
return false;
if (attr1->attstattarget != attr2->attstattarget)
return false;
if (attr1->attlen != attr2->attlen)
return false;
if (attr1->attndims != attr2->attndims)
return false;
if (attr1->atttypmod != attr2->atttypmod)
return false;
if (attr1->attbyval != attr2->attbyval)
return false;
if (attr1->attstorage != attr2->attstorage)
return false;
if (attr1->attalign != attr2->attalign)
return false;
if (attr1->attnotnull != attr2->attnotnull)
return false;
if (attr1->atthasdef != attr2->atthasdef)