Re: jsonb format is pessimal for toast compression

On Sep 4, 2014, at 7:26 PM, Jan Wieck <jan(at)wi3ck(dot)info> wrote:

> This is only because the input data was exact copies of the same strings over and over again. PGLZ can very well compress slightly less identical strings of varying lengths too. Not as well, but well enough. But I suspect such input data would make it fail again, even with lengths.

We had a bit of discussion about JSONB compression at PDXPUG Day this morning. Josh polled the room, and about half though we should apply the patch for better compression, while the other half seemed to want faster access operations. (Some folks no doubt voted for both.) But in the ensuing discussion, I started to think that maybe we should leave it as it is, for two reasons:

1. There has been a fair amount of discussion about ways to better deal with this in future releases, such as hints to TOAST about how to compress, or the application of different compression algorithms (or pluggable compression). I’m assuming that leaving it as-is does not remove those possibilities.

2. The major advantage of JSONB is fast access operations. If those are not as important for a given use case as storage space, there’s still the JSON type, which *does* compress reasonably well. IOW, We already have a JSON alternative the compresses well. So why make the same (or similar) trade-offs with JSONB?

Just my $0.02. I would like to see some consensus on this, soon, though, as I am eager to get 9.4 and JSONB, regardless of the outcome!

Best,

David