We did a little more digging on our side, which I apologize for not doing beforehand.
We wrote a script to create a simple table with a jsonb column, inserted some json data into the column and then used
pg_column_size to test the size of the jsonb data column.
We ran the script against local docker versions of postgres 14.8 and 15.5 and saw that the data in the jsonb column was the same size.
We then ran the script on AWS RDS Postgres and saw a size difference for the same json data between versions 14.8 and 15.4 (we also saw the larger size on RDS postgres 15.5 and 16.1).
| Version | size (kb) | notes |
| RDS Postgres-14.8 | 1587 | (the same size we were seeing locally) |
| RDS Postgres-15.4 | 2112 |
|
Thank you for your prompt responses and assistance.
If you are curious, I can share the script we used with you.
We have a process that runs once an hour to read the .dat file in csv format then a node script using the
pg package version "8.8.0" to create the json objects and insert the data records as jsonb data.
None of the upload process changed during the underlying database upgrade.
Basic debugging requires the existence of a self-contained reproducer. In this case ideally one that only uses psql and some static (already processed) data files, and that is known to produce the observed behaviors on non-RDS PostgreSQL.
David J.