| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "David E(dot) Wheeler" <david(at)justatheory(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Jan Wieck <jan(at)wi3ck(dot)info> |
| Subject: | Re: jsonb format is pessimal for toast compression |
| Date: | 2014-09-15 23:44:07 |
| Message-ID: | CAM3SWZRLm47+Ga6APecLMNu7devfLehyvQe-73ObUgec-Cjr5Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Sep 15, 2014 at 4:05 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> Actually, having the keys all at the same level *is* relevant for the
> issue we're discussing. If those 270 keys are organized in a tree, it's
> not the same as having them all on one level (and not as problematic).
I believe Robert meant that the 270 keys are not at the top level, but
are at some level (in other words, some object has 270 pairs). That is
equivalent to having them at the top level for the purposes of this
discussion.
FWIW, I am slightly concerned about weighing use cases around very
large JSON documents too heavily. Having enormous jsonb documents just
isn't going to work out that well, but neither will equivalent designs
in popular document database systems for similar reasons. For example,
the maximum BSON document size supported by MongoDB is 16 megabytes,
and that seems to be something that their users don't care too much
about. Having 270 pairs in an object isn't unreasonable, but it isn't
going to be all that common either.
--
Peter Geoghegan
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