HP NonStop G-Series - Manual (Page 45)

SDR Operations
HP NonStop SQL DDL Replicator User’s Guide —545799-005
4-5
Special cases
not know that they apply to a catalog and cannot discard them. More specifically, RDF
events 736 appear in the EMS log, when the RDF updater detects the SQL updates to
the catalog table VERSIONS:
Waiting to obtain FILEINFO on file $vol.catsubvol.VERSIONS, error 11
SDR detects this situation and updates the depot file with a CREATE CATALOG before
the audited catalog inserts. The CREATE CATALOG will be replicated before the RDF
updater would stall at the catalog inserts. The downside of this strategy is that there is
a very slight chance that the primary CREATE CATALOG could be aborted and SDR
could create a backup catalog where no primary catalog was created. But, this is not
likely to have any adverse effect on maintaining a consistent duplicate database.
CREATE Collation
SDR replicates CREATE COLLATION on the backup system in two steps: first it
translates the name of the collation and the input edit file used by the collation
compiler, then it executes a SQL CREATE COLLATION statement.
SQL in turn executes the CREATE COLLATION in two steps: first it creates a special
audited file to be used for output by the collation compiler, then it invokes the collation
compiler that makes audited updates to its output file.
Because there are additional files involved, there are potential issues in replicating
CREATE COLLATION relating to the use of these files.
The collation compiler input file
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Since edit files are not replicated by RDF, you must ensure that the same character
processing rules are present on both systems before executing the CREATE
COLLATION on the primary system.
If the input edit file does not exist on the backup system, SDR will continue to retry
the CREATE COLLATION until the input file is created or until you cancel the
operation.
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Not only must the input edit file exist on the backup system, but it must also be in
sync with the input file on the primary. Problems will occur if the primary input file is
updated and an out-of-date file still exists on the backup.
The audited collation output file
The audited updates that the collation compiler makes to its output file cause RDF to
stall, because the corresponding audited compiler output file does not exist on the
backup system.
Note. If you have automated the replication of non database files between your primary and
backup systems, be sure to include the collation compiler input edit file into your automatically
replicated file sets.