dms error for postgres db

Based on the log entry you've shared, your AWS Database Migration Service (DMS) task is using the test_decoding plugin for capturing changes from your PostgreSQL source database. This is evident from the log file reference to "postgres_test_decoding.c".

The test_decoding plugin is one of the logical decoding plugins that DMS can use when replicating from PostgreSQL databases. It processes database changes and converts them into a human-readable format, which DMS then uses to replicate those changes to the target database.

The specific error indicates that DMS encountered an issue when querying for a column named 'group_code' in a table called 'metadata' within the 'apps' schema. This could be due to various reasons such as permission issues, the column not existing, or other configuration problems.

It's worth noting that the test_decoding plugin can lead to higher network bandwidth usage during high-volume transactions because it generates output in a human-readable format that is larger than binary formats. If you're experiencing performance issues, you might consider using the pglogical plugin instead, which uses a binary format and results in compressed WAL (Write Ahead Log) stream changes, potentially improving replication performance.
Sources
PostgreSQL Endpoint Troubleshooting - AWS Database Migration Service