>>>>> "Rod" == Rod Taylor <rbt@rbt.ca> writes:
>> This is exactly the reason why in db2 _no_ guarantees are made >> regarding the constancy of the system
catalogs(that are in the >> SYSIBM schema). Instead, the equivalent views (in the SYSCAT >> schema) are _never_
broken(whether in a point release or a new >> version). In fact, the SYSCAT views correspond to the ISO SQL >>
standard.
Rod> The INFORMATION_SCHEMA? Out of curiousity, how do they Rod> handle DB2 extensions? Do they create new views
inthat Rod> schema? Do they ignore them?
Yes, the INFO SCHEMA - thankfully it's long enough since I looked at
the SQL specs .. I've started forgetting terms. If I never have to
write or read any spec material again, it won't be too soon.
Why extensions, even for things like indexes that aren't in the
standard, they create views (SYSCAT.INDEXES, SYSCAT.INDEXAUTH etc.)
Rod> I'm going with the assumptions DB2 has extended SQL specs in Rod> some shape or form.
Certainly - it's just that the meaning and number of existing columns
and rows in the syscat views are always backward compatible. That
includes support of the info schema - for the sql standard features
that db2 supports.
So if there's something new in the catalog tables that is a result of
an extension and doesn't appear as a column in the syscat views (or
the info schema) then an appropriate column may be added to the view -
provided that this doesn't break the info schema compatibility.
--
Pip-pip
Sailesh
http://www.cs.berkeley.edu/~sailesh