Open log replication and physical ReadOnly database

[Lucas Rangel Gazire]

Hi all!

Another question just popped up.

Can we use the olr option in the readonly database without the needing to use the master database?

As far as i check olr  does not need to do any write or query in the master.

Thanks again,

Lucas Gazire.

[Chris Cranford]

Hi Lucas -

So the main issue with PHYSICAL standby databases is that there is no immediate SQL access, these environments are started in an effective single-user mode where RMAN is perpetually applying redo log changes so that the database is an exact replica of the primary at a block-by-block basis. Debezium requires a connection to the underlying database for several specific use cases such as temporal type value conversion, validating the offset position with the database's archive and redo logs, and others.  While none of these operations write to the database, a read-only connection is mandatory.

So while you can use OpenLogReplicator in both an online and offline reader mode; this only applies at the streaming level, but yet there are data use cases where Debezium may need to make a call back into the database during value conversion so that we always emit values uniformly regardless of the adapter we're reading with.

In closing, you could use OpenLogReplicator with Debezium with a LOGICAL standby with read-only permissions without any issue; however, PHYSICAL standby environments are not currently supported.

Chris

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