[pgpointcloud] Toast(ed)

[Howard Butler]

On Feb 6, 2014, at 11:57 AM, Paul Ramsey <pramsey at cleverelephant.ca> wrote:

> Howard,
> The thing to note is that, when you “TOAST” a tuple that is larger than the page size, you just cut it into page-sized chunks and store it into a side table.
> So, you still get a billion records for your trillion point case, you just get them somewhere hidden off to the side.

Good to know.

> Similarly if we moved to using blobs instead, we’d still end up with a billion records (maybe not in one table, that would be an implementation question) http://www.postgresql.org/docs/current/static/lo-implementation.html

(facitiously parenthetical) Why are you busting up my big, continuous blob data into tiny little bits?

> Since we store patches with practically no extra information next to them in the tuple, just reading the PC_MemSize (I think that’s the function) of the patch gives an idea of storage you can use to bump up your patch size to close to the maximum (8kb). 

Is there a way we could communicate from the db to drivers.pgpointcloud.writer an automatic toast'able patch size based on this info?

> You can also recompile your database with a higher page size if you’re feeling hacky.

Is there any possibility that pg could be improved to allow tables of varying page sizes? I suppose increasing the page size generally across an entire database could cause some unforeseen pathologies.

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