DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

Summary of DB2 Catalog changes
The most important changes are:
► Introduction of long names
Long names (varchar 128) are supported for most of the objects. Catalogs are defined
using Unicode, so if you have existing queries on the catalog, you will receive the results in
a different ordering.
► New tables
– SYSIBM.IPLIST: Multiple IP addresses to one LOCATION can be defined for data
sharing group.
– SYSIBM.SYSSEQUENCEAUTH: Created in DSNDB06.SYSSEQ2. It records the
privileges that are held by users over sequences.
– SYSIBM.SYSOBDS: Created in DSNDB06.SYSALTER, it contains the version of a
table space or an index space that is still needed for recovery.
► New table spaces:
– SYSEBCDC: EBCDIC table space, not used until NFM
SYSIBM.SYSDUMMY1: has been moved from SYSSTR to SYSEBCDC
– SYSALTER: New catalog table SYSIBM.SYSOBDS
To store prior version information of ALTERed tables
– SYSIBM.IPLIST: Created in DSNDB06.SYSDDF
Allows multiple IP addresses to be specified for a given LOCATION
► Column changes
– Existing binary columns will be ALTERed to be FOR BIT DATA columns to ensure they
are handled properly during ENFM processing
– Approximately 60 columns added to existing tables
– Approximately 15 changes to values of existing columns
– Approximately 45 column definitions have been changed
– Approximately 10 changes to RI and table check constraints
– Column length changes to support long names are only done during ENFM processing
In summary, 17 catalog and 1 directory table space have been converted to Unicode, two
tables have been dropped (SYSLINKS - No index data sets to be deleted,
SYSPROCEDURES - VSAM data sets for Index DSNKCX01 can be deleted after ENFM),
the table SYSIBM.SYSDUMMY1 has been moved from DSNDB06.SYSSTR to
DSNDB06.SYSEDCBC, many columns have changed to VARCHAR to support long
names, system-defined catalog indexes changed to NOT PADDED and 7 catalog and 1
directory table space moved out of BP0.
► Default changes
The initial defaults for the - ALTER BUFFERPOOL command have changed:
– DWQT: Specifies the buffer pool’s deferred write threshold as a default percentage of
the total virtual buffer pool size. The initial default is decreased from 50% to 30%.
– VDWQT: Specifies the virtual deferred write threshold for the virtual buffer pool. This
parameter accepts two arguments. The first argument is a percentage of the total
virtual buffer pool size. The default is decreased from 10% to 5%.
The initial defaults for the ALTER GROUPBUFFERPOOL command have changed:
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