Re: [GENERAL] WAL being written during SELECT * query

> >> On Tue, Apr 4, 2017 at 9:46 AM, Tom DalPozzo <t.dalpozzo@gmail.com>
> >> wrote:
> >> > Hi,
> >> > I have a very big table (10GB).
> >> > I noticed that many WAL segments are being written when elaborating read
> >> > only transactions like this:
> >> > select * from dati25600000000 where id >43000000 limit 1000000;
> >> > I don't understand why are there WAL writings during read only
> >> transactions.

These are hint bits. The mechanism and behavior are known and documented:
https://wiki.postgresql.org/wiki/Hint_Bits

--
Bill Moran <wmoran@potentialtech.com>