Re: A tiny improvement of psql

On 12/26/23 17:36, Tom Lane wrote:
> Kevin Wang <kevinpgcloud@gmail.com> writes:
>> As you know, we can use the UP arrow key to get the previous command to
>> avoid extra typing. This is a wonderful feature to save the lives of every
>> DBA. However, if I type the commands like this sequence: A, B, B, B, B, B,
>> B,  as you can see, B is the last command I execute.
> 
>> But if I try to get command A, I have to press the UP key 7 times.  I think
>> the best way is: when you press the UP key, plsql should show the command
>> that is different from the previous command, so the recall sequence should
>> be B -> A, not B -> B -> ... -> A.  Then I only press the UP key 2 times to
>> get command A.
> 
> This is driven by libreadline, not anything we control.  I have
> seen the behavior you describe in some other programs, so I wonder
> whether it's configurable.

It is kind of something we control.  Per the psql docs, setting

     HISTCONTROL=ignoredups

will do the trick.

https://www.postgresql.org/docs/current/app-psql.html#APP-PSQL-VARIABLES-HISTCONTROL
-- 
Vik Fearing