User's Manual

Using passthrough mode
The publisher of the consolidated database can directly intervene at remote
sites using a passthrough mode, which enables standard SQL statements to
be passed through to a remote site.
Determining recipients of
passthrough statements
Passthrough destinations are determined by sp_passthrough_user and
sp_passthrough_subscription. Executing either of these procedures
determines a set of recipients for any subsequent passthrough statements.
Executing either sp_passthrough_user and sp_passthrough_subscription
adds to the current list of recipients. The sp_passthrough_stop procedure
resets passthrough (that is, resets the list of recipients to be empty).
In Adaptive Server Enterprise, sp_passthrough never executes statements in
the consolidated database. Passthrough SQL statements are applied only to
remote databases.
Passthrough statements To cause passthrough SQL statements to replicate, you call sp_passthrough.
Due to the VARCHAR(255) limitation in Adaptive Server Enterprise, you
should build a long SQL statement up in pieces. Calls to
sp_passthrough_piece will build up a single SQL statement. Calling
sp_passthrough with the last piece will cause the built up statement to
replicate.
Notes on using
passthrough mode
♦ You should always test your passthrough operations on a test database
with a remote database subscribed. You should never run untested
passthrough scripts against a production database.
♦ You should always qualify object names with the owner name.
PASSTHROUGH statements are not executed at remote databases from
the same user ID. Consequently, object names without the owner name
qualifier may not be resolved correctly.
Schema modifications
The Adaptive Server Enterprise log transfer interface does not contain
information about the number of columns and data types of the columns in a
table. SSREMOTE gets this information directly from the Adaptive Server
Enterprise system tables. For this reason, altering a table and then scanning
operations that happened before the ALTER TABLE will lead to errors.
SSREMOTE must set the “truncation point” beyond all operations on
replicated tables before schema changes can be made. Operations on
replicated tables need to be prevented between SSREMOTE running and the
schema changes being made.
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