Question 1

How to set up bi-directional replication with pgcat?

Accepted Answer

Create pgcat users with replication attributes on both databases, configure publications and subscriptions using the pgcat_subscription table, and run pgcat with a YAML config. Ensure local change filtering is enabled to prevent loops, as described in the README.

Question 2

pgcat vs PostgreSQL native logical replication: which is better for my use case?

Accepted Answer

Use pgcat if you need advanced features like table mapping, replication to views, or built-in conflict resolution. For basic replication between standard tables, PostgreSQL's native replication in versions 13+ might be simpler with less setup overhead.

Question 3

Does pgcat support conflict resolution for distributed databases?

Accepted Answer

Yes, pgcat includes optional last-writer-win conflict resolution with timestamps or counters. You must run pgcat_setup_lww on all instances and configure it via YAML files to handle concurrent updates across replicas.

Question 4

How to handle replication conflicts in pgcat without using LWW?

Accepted Answer

Without LWW, conflicts cause pgcat to panic and restart. You can manually skip transactions by updating the pgcat_subscription_progress table with the LSN from the error log, which requires monitoring and intervention.

Question 5

Can pgcat replicate to partitioned tables in older PostgreSQL versions?

Accepted Answer

Yes, pgcat supports replicating to partitioned tables even in PostgreSQL versions before 13, where native replication didn't allow it. This is a key enhancement over built-in features.

Question 6

What are the performance implications of using pgcat?

Accepted Answer

pgcat uses high-level SQL commands and runs as a separate Go process, which may add latency compared to native replication. However, it maximizes compatibility with various table types, so performance depends on configuration and network conditions.

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