Sandhya Sundaresan created TRAFODION-2508:
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Summary: Document CQD for sort scratch disk selection
Key: TRAFODION-2508
URL: https://issues.apache.org/jira/browse/TRAFODION-2508
Project: Apache Trafodion
Issue Type: Documentation
Components: documentation
Reporter: Sandhya Sundaresan
Assignee: Liu Yu
https://issues.apache.org/jira/browse/TRAFODION-2146
STFS_HDD_LOCATION is set in ms.env as part of install. This is by default the
location of overflow disks. To make a change to this setting requires
trafodion to be bounced.
The cqd option has been added. This option allows setting the overflow disks in
the form of CQD in the defaults table. This does not require trafodion to be
restarted to make the overflow disk settings effective.
The format for specifying the scratch disks is as follows :
control query default SCRATCH_DIRS ‘/tmp2:/tmp3:/tmp4/scratch’
Currently STFS_HDD_LOCATION is used by default. CQD option is available if
STFS_HDD_LOCATION needs to be overridden in the field if customer configured
disk changes.
It’s basically a “:” separated list of directories. Ensure all these disks on
every node exist and that each of these directories has Trafodion access.
Scratch files of format SCR<*****> are created in the newly specified
directories when queries that need to overflow like sort and hash join queries
are run.
Possible errors :
If the format of the directories is incorrect or they don’t exist on the
system, an error will be returned when the query is prepared – compile time.
If the user does not have Trafodion access the query may fail at runtime.
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