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How to change MaxParseTreeSegs parameter value?

To change MaxParseTreeSegs value, kindly follow the below steps:

1) Connect to any of the Teradata host or you can do this from Viewpoint also.

2) Enter DBSControl

# dbscontrol

Release Version
DBSControl Utility (Dec 99)

The current DBS Control GDO has been read.

Enter a command, HELP, or QUIT:

3) Enter below command to display current settings

di perf


display performance
DBS Control Record – Performance Fields:

1. DictionaryCacheSize = 8192 (KB; Default value)
2. DBSCacheCtrl = TRUE (Enabled)
3. DBSCacheThr = 10 (Percent; Default value)
4. MaxParseTreeSegs = 2000
5. ReadAhead = TRUE (Enabled)

Here you will see MaxParseTreeSegs (4th row) is set to 2000

4) Run below command to chnage this value to 4000 or desired number what you want to set to.

modify perf 4=4000

The MaxParseTreeSegs field has been modified from 2000 to 4000.
NOTE: This change will become effective after the DBS Control Record
has been written.

5) Now, you have to issue write command for this change to take effect.


Locking the DBS Control GDO…
Updating the DBS Control GDO…

6) Make a new connection and your sql will now use newer value. No Teradata restart is needed for the change to take effect.