3 ms·

Major version jumps are always fun. Recently I discovered RDS recommends pglogical over built in replication for a reason, the latter doesn't work well in RDS w

Major version jumps are always fun. Recently I discovered RDS recommends pglogical over built in replication for a reason, the latter doesn't work well in RDS with larger than RAM replica logs.

taspeotis 4y ago
Hey, we use logical replication on RDS. Never considered pglogical. Do you have a link to Amazon’s recommendation of pglogical?
- paulryanrogers 4y ago
  So I was using their guide for minimal downtime upgrades [0], see option 'D'. And I was replicating Pg 11 to 14. Logical replication appeared to work in that case yet big tables would never catch up or appear to get truncated. If you're replicating among nodes at the same Pg version then built-in replication may work for you. Once I switched to pglogical jumping major versions worked as intended. Now it's possible in the rush I used the wrong setting somewhere and built-in logical replication can work between major versions. Though I lost enough time experimenting I'll keep using pglogical until AWS officially recommends something else. [0] https://aws.amazon.com/blogs/database/part-1-upgrade-your-amazon-rds-for-postgresql-database-comparing-upgrade-approaches/ https://aws.amazon.com/blogs/database/part-1-upgrade-your-am...
  - taspeotis 4y ago
    Thank you!
PikachuEXE 4y ago
I have never used RDS. Anyway here is a post for using built-in logical replication. https://dev.to/pikachuexe/postgresql-logical-replication-for-upgrade-41hl https://dev.to/pikachuexe/postgresql-logical-replication-for...
- paulryanrogers 4y ago
  Posts like this didn't help in my case. Though depending on versions being replicated and RDS settings it could work.
  - PikachuEXE 4y ago
    Ya there are many managed services and limitations around those. Only throwing out this as a reference.
olau 4y ago
Aurora doesn't work with a query that computes a temporary table larger than memory either. Amazon's Postgres things are not Postgres.
- paulryanrogers 4y ago
  I wasn't using Aurora at the time. And I don't expect non-Aurora RDS to be exactly the same as vanilla Postgres either. Still, it was surprising that the old Pg solution is supported (pglogical) while the new one wasn't yet, at least for my version jump.

Major version jumps are always fun. Recently I discovered RDS recommends pglogical over built in replication for a reason, the latter doesn't work well in RDS with larger than RAM replica logs.

taspeotis 4y ago

Hey, we use logical replication on RDS. Never considered pglogical. Do you have a link to Amazon’s recommendation of pglogical?

paulryanrogers 4y ago
So I was using their guide for minimal downtime upgrades [0], see option 'D'. And I was replicating Pg 11 to 14. Logical replication appeared to work in that case yet big tables would never catch up or appear to get truncated. If you're replicating among nodes at the same Pg version then built-in replication may work for you. Once I switched to pglogical jumping major versions worked as intended. Now it's possible in the rush I used the wrong setting somewhere and built-in logical replication can work between major versions. Though I lost enough time experimenting I'll keep using pglogical until AWS officially recommends something else. [0] https://aws.amazon.com/blogs/database/part-1-upgrade-your-amazon-rds-for-postgresql-database-comparing-upgrade-approaches/ https://aws.amazon.com/blogs/database/part-1-upgrade-your-am...
- taspeotis 4y ago
  Thank you!

PikachuEXE 4y ago

I have never used RDS. Anyway here is a post for using built-in logical replication. https://dev.to/pikachuexe/postgresql-logical-replication-for-upgrade-41hl https://dev.to/pikachuexe/postgresql-logical-replication-for...

paulryanrogers 4y ago
Posts like this didn't help in my case. Though depending on versions being replicated and RDS settings it could work.
- PikachuEXE 4y ago
  Ya there are many managed services and limitations around those. Only throwing out this as a reference.

olau 4y ago

Aurora doesn't work with a query that computes a temporary table larger than memory either. Amazon's Postgres things are not Postgres.

paulryanrogers 4y ago
I wasn't using Aurora at the time. And I don't expect non-Aurora RDS to be exactly the same as vanilla Postgres either. Still, it was surprising that the old Pg solution is supported (pglogical) while the new one wasn't yet, at least for my version jump.