Re: [HACKERS] Custom compression methods

On Thu, Apr 8, 2021 at 3:38 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> It looks like this should not remove the word "data" ?

Oh, yes, right.

>  The compression technique used for either in-line or out-of-line compressed
> -data is a fairly simple and very fast member
> -of the LZ family of compression techniques.  See
> -<filename>src/common/pg_lzcompress.c</filename> for the details.
> +can be selected using the <literal>COMPRESSION</literal> option on a per-column
> +basis when creating a table. The default for columns with no explicit setting
> +is taken from the value of <xref linkend="guc-default-toast-compression" />.
>
> I thought this patch would need to update parts about borrowing 2 spare bits,
> but maybe that's the wrong header..before.

We're not borrowing any more bits from the places where we were
borrowing 2 bits before. We are borrowing 2 bits from places that
don't seem to be discussed in detail here, where no bits were borrowed
before.

-- 
Robert Haas
EDB: http://www.enterprisedb.com