if_modified_func

Track changes to a table at the statement and/or row level.

Optional parameters to trigger in CREATE TRIGGER call:

param 0: boolean, whether to log the query text. Default ‘t’.

param 1: text[], columns to ignore in updates. Default [].

     Updates to ignored cols are omitted from changed_fields.

     Updates with only ignored cols changed are not inserted
     into the audit log.

     Almost all the processing work is still done for updates
     that ignored. If you need to save the load, you need to use
     WHEN clause on the trigger instead.

     No warning or error is issued if ignored_cols contains columns
     that do not exist in the target table. This lets you specify
     a standard set of ignored columns.

There is no parameter to disable logging of values. Add this trigger as
a ‘FOR EACH STATEMENT’ rather than ‘FOR EACH ROW’ trigger if you do not
want to log row values.

Note that the user name logged is the login role for the session. The audit trigger
cannot obtain the active role because it is reset by the SECURITY DEFINER invocation
of the audit trigger its self.

LizSync has added its own sync_data column to store the needed information for synchronisation purpose.

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