Ke:
There is no harm to running drop crcols or any of the others if the table does not have them, you just get an error. Witness:
> alter table extents drop crcols;
19814: Cannot drop CRCOLS when table does not have replication shadow columns.
Error in line 1
Near character position 30
As far as identifying which tables have shadow columns, most are only indicated by a flag in the systables record for the table. The easiest way would be to run dbschema -ss or myschema and search for the "with ..." clauses (upper case in myschema output, lower case from dbschema). I do not think that dropping shadow columns is an in-place alter so it would be best to drop all that a table has in a single ALTER statement.
Yes, you should rerun your UPDATE STATISTICS after the alters.
Art
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Art S. Kagel, President and Principal Consultant
ASK Database Management Corp.
www.askdbmgt.com------------------------------
Original Message:
Sent: Sun March 22, 2026 11:19 PM
From: ke chen
Subject: Shadow column
May I ask how to retrieve a table list for all the user tables that have shadow columns? (going to retire CDR).
If after we stop using CDR, would it safe to drop shadow columns (by: ALTER TABLE table_name DROP CRCOLS;) from all user tables?
After drop shadow columns, shall we run update statistics on all those tables?
thank you for your advice.
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ke chen
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