Re: Bit data type header reduction in some cases

On Tue, Feb 25, 2014 at 09:32:55AM -0500, Tom Lane wrote:
> Heikki Linnakangas <hlinnakangas@vmware.com> writes:
> > On 02/25/2014 08:23 AM, Haribabu Kommi wrote:
> >> It's regarding a Todo item of "Bit data type header reduction" in some
> >> cases. The header contains two parts. 1)  The varlena header is
> >> automatically converted to 1 byte header from 4 bytes in case of small
> >> data. 2) The bit length header called "bit_len" to store the actual bit
> >> length which is of 4 bytes in size. I want to reduce this bit_len size to 1
> >> byte in some cases as similar to varlena header. With this change the size
> >> of the column reduced by 3 bytes, thus shows very good decrease in disk
> >> usage.
> 
> > [ various contorted schemes for doing that backward-compatibly ]
> 
> TBH, this sounds like a huge amount of effort and a significant risk of
> new bugs in return for not darn much.  Who uses bit values anyway?
> They were removed from the SQL spec more than 10 years ago.  And of that
> population, who cares about a byte or two per value?  The field demand
> for this is not only zero, it's probably negative.  (The thread referenced
> by the TODO entry shows no evidence of user demand.)

OK, TODO item removed.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + Everyone has their own god. +