On 12/12/2017 04:33 PM, Robert Haas wrote:
> you want to upgrade your existing tables to use lz4 rather than pglz,
> you can change the compression option for those columns to COMPRESS
> lz4 PRESERVE pglz if you want to do it incrementally or just COMPRESS
This is a thread I've only been following peripherally, so forgive
a question that's probably covered somewhere upthread: how will this
be done? Surely not with compression-type bits in each tuple? By
remembering a txid where the compression was changed, and the former
algorithm for older txids?
-Chap