Re: Very Limited Toast Compression on JSONB (9.4 beta 2)

On 07/31/2014 01:44 PM, Larry White wrote:
> Hi,
>
> I'm running an experiment on 9.4 beta 2.
>
> I put 275,000 identical JSON files into a table using JSONB (one per
> row).  Each raw text file is 251K in size, so the total uncompressed is
> 69GB. The column storage is set to EXTENDED.  There are other toastable
> columns in the table, but none have more than 36 bytes of data in them.
>
> My Toast table is 66GB. I would have expected to get that much (or more)
> compression just from JSONB being a binary format.
>
> If I compress one of these JSON files outside of Postgres, it goes from
> 251K to 1K. So each file should theoretically fit on a single row in the
> toast table. In total, the amount well under a GB when compressed
> outside of PG.
>
> Any guesses as to why there is so little compression of this data or how
> I might remedy the situation?

Are you sure the column storage is EXTENDED and not EXTERNAL?

>
> Thanks much for your help.
>
>
> Larry
>
>
>


--
Adrian Klaver
adrian.klaver@aklaver.com