Re: jsonb format is pessimal for toast compression

On 08/08/2014 08:02 AM, Tom Lane wrote:
> 2. Are we going to ship 9.4 without fixing this?  I definitely don't see
> replacing pg_lzcompress as being on the agenda for 9.4, whereas changing
> jsonb is still within the bounds of reason.
> 
> Considering all the hype that's built up around jsonb, shipping a design
> with a fundamental performance handicap doesn't seem like a good plan
> to me.  We could perhaps band-aid around it by using different compression
> parameters for jsonb, although that would require some painful API changes
> since toast_compress_datum() doesn't know what datatype it's operating on.

I would rather ship late than ship a noncompressable JSONB.

One we ship 9.4, many users are going to load 100's of GB into JSONB
fields.  Even if we fix the compressability issue in 9.5, those users
won't be able to fix the compression without rewriting all their data,
which could be prohibitive.  And we'll be  in a position where we have
to support the 9.4 JSONB format/compression technique for years so that
users aren't blocked from upgrading.

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com