Hi,
8b38a538c0aa5a432dacd90f10805dc667a3d1a0 changed things so that all
columns are checked for NOT NULL ness. Which is fine in general, but it
currently does make it impossible to have a varlena column (except
OID/INT2 vector...) as a key column in syscache. Even if the column is
factually NOT NUL.
The rule for determining attribute's NOT NULL setting in bootstrap is:
/*
* Mark as "not null" if type is fixed-width and prior columns are too.
* This corresponds to case where column can be accessed directly via C
* struct declaration.
*
* oidvector and int2vector are also treated as not-nullable, even
though
* they are no longer fixed-width.
*/
#define MARKNOTNULL(att) \
((att)->attlen > 0 || \
(att)->atttypid == OIDVECTOROID || \
(att)->atttypid == INT2VECTOROID)
if (MARKNOTNULL(attrtypes[attnum]))
{
int i;
for (i = 0; i < attnum; i++)
{
if (!MARKNOTNULL(attrtypes[i]))
break;
}
if (i == attnum)
attrtypes[attnum]->attnotnull = true;
}
(the rule is also encoded in genbki.pl)
Now, you can argue that it's a folly to use the syscache code to access
something via a text column (which is what I want to do). I don't agree,
but even if you're of that position, it seems worthwhile to mark further
catalog columns as NOT NULL in the catalog if that's what the code
expects?
E.g. pg_(sh)?seclabel.provider should certainly be NOT
NULL. pg_extension.extversion as well. There's a couple more I think.
So, how about providing bootstrap infrastructure for marking columns as
NOT NULL?
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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