Binary data performance in PostgreSQL
The tricky part in this case, as the original poster notes, is that the data is binary data taken from a binary file and is not compressed.
The concern raised is whether PostgreSQL has compressed it, or compressed all of it across different rows. The poster suspects that PostgreSQL's compression algorithm might shrink binary data in some rows but not in others. That could lead to a mixed situation where binary data is compressed in some rows and left uncompressed in others.
There is also a worry about switching the storage setting to EXTERNAL: the poster is concerned this could create compatibility issues, for example PostgreSQL being unable to read the existing compressed data.
