I
am upgrading our existing 12.22 Aurora Postgresql clusters to 16.8
using: https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.MajorVersionUpgrade.html
I
have created a pub sub replication with a slot per database. I
originally created 1 publication for each database for all tables.
Due to this appeared issue, I have changed that method to creating
1 publication per schema. This allows limiting a smaller set of
tables from the subscription.
Either
way getting errors:
2025-04-16
18:47:11 UTC::@:[1633]:LOG: logical replication apply worker for
subscription "clone_rep_slot_cdc_only_sub" has started
2025-04-16
18:47:12 UTC::@:[1633]:ERROR: could not identify an equality
operator for type xml
2025-04-16
18:47:12 UTC::@:[1633]:CONTEXT: processing remote data for
replication origin "pg_2141834" during message type "UPDATE" for
replication target relation "sde.gdb_items" in transaction
151772192, finished at 0/61601498
2025-04-16
18:47:12 UTC::@:[569]:LOG: background worker "logical replication
worker" (PID 1633) exited with exit code 1
It
appears to be failing on the gdb_items table because there are
columns of datatype xml. The only way I could get this to run was
to exclude tables from the sde schema with datatype xml in the
schema publication. Or remove the entire schema publication from
the subscription. Once I remove the table(s) in question the slot
becomes active.
Is
this an undocumented limitation? I cannot find this limitation
anywhere, in aws docs: https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/blue-green-deployments-considerations.html#blue-green-deployments-limitations-postgres-logical
Nor
in Postgresql version 16: https://www.postgresql.org/docs/16/logical-replication-restrictions.html
Should
logical replication fail due to a column of type 'xml' in a table
in a publication?
I
assume this issue in replication is related to this excerpt from
docs:
8.13.3. Accessing
XML Values
The
xml data
type is unusual in that it does not provide any comparison
operators. This is because there is no well-defined and
universally useful comparison algorithm for XML data. ...