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Viewing hidden columns associated with every table

Question & Answer


Question

What are the hidden columns associated with every table?

Answer

The following hidden columns are associated with every table:

datasliceid
 -- describes the dataslice the data resides on.
createxid
 -- describes the transactionID for the row.
rowid
 -- describes a unique rowID number which is unique per NPS instance.
deletexid
 -- describes whether or not the row is deleted or not.

By default all of the above are available and can be used in a SQL statement.
However, you can not run a 

     select * from <table> where deletexid <> 0; 

with the intent of seeing deleted rows.

However, by defining the following setting in the /nz/data/config/system.cfg file:

     host.fpgaAllowXIDOverride yes 

and restarting NPS, you can then see deleted rows. This is strongly discouraged.

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Historical Number

NZ045573

Document Information

Modified date:
17 October 2019

UID

swg21577045