Updating Table Space Statistics
Use the Table Space Statistics window to
run utility RUNSTATS against a table space.
You can gather summary information about
the characteristics of data in table spaces,
indexes and partitions. The output is recorded
in the DB2 for OS/390 catalog tables. DB2
uses this information to select access paths
to data during the bind process. The information
is available to the database administrator
for evaluating database design and to aid
in determining when table spaces or indexes
must be reorganized.
Authorities and privileges
To gather table space statistics:
-
Open the Table Space Statistics window.
- At the Share level radio buttons, decide on the access that
other programs can use on the table space
while RUNSTATS is running.
- Specify the Reference only radio button if you want to allow only read-only
access by other programs. This is the
default.
- Specify the Allow changes radio button if you want to allow other
programs to change the table space
or index.
Uncommitted data can be collected into
statistical
summaries.
- At the Report statistics radio buttons, specify if a set of messages
is generated to report the collected
statistics.
Specify Yes if you want the set of mesages output to
the SYSPRINT data set. The default is
that
no messages are sent to SYSPRINT.
- Specify one of the Update options on catalog tables radio buttons to decide whether the collected
statistics are inserted into the catalog
tables:
- Access path and space statistics
-
The utility updates all the statistics in
the DB2 catalog.
- Access path statistics only
-
The utility updates only the catalog table
columns used for access path selection.
- Space statistics only
-
The utility updates only the catalog table
colums that help a database administrator
assess the status of a particular table
space
or index.
- Do not update catalog tables
-
The utility does not update any catalog statistics.
This is only valid if Report Statistics radio button is YES.
- Select the Collect statistics on auxilliary indexes check box to gather statistics on the index
that is associated with large object table
spaces (LOBs). You can specify that a LOB
table space is to have space statistics
collected
so that you can determine when the LOB
table
space should be reorganized. No statistics
on the LOB table space affect access path
selection.
- Click OK to run the statistics utility.