Re: What does "merge-joinable join conditions" mean ???? - Mailing list pgsql-sql

From Tom Lane
Subject Re: What does "merge-joinable join conditions" mean ????
Date
Msg-id 17050.1137362308@sss.pgh.pa.us
Whole thread Raw
In response to What does "merge-joinable join conditions" mean ????  ("Dean Gibson (DB Administrator)" <postgresql4@ultimeth.com>)
List pgsql-sql
"Dean Gibson (DB Administrator)" <postgresql4@ultimeth.com> writes:
> I have a FULL JOIN between two simple tables, and am getting the message 
> " Query failed: ERROR:  FULL JOIN is only supported with merge-joinable 
> join conditions"

> I'd be glad to fix this in my query if I knew what the #@!! it meant.  

The join condition(s) of a FULL JOIN have to be mergejoinable, which
basically means an equality relation between sortable (btree-indexable)
data types.  You can see exactly which operators are mergejoinable with
a query like

select oid::regoperator from pg_operator where oprlsortop != 0;
        regards, tom lane


pgsql-sql by date:

Previous
From: Michael Fuhr
Date:
Subject: Re: What does "merge-joinable join conditions" mean ????
Next
From: Tom Lane
Date:
Subject: Re: What does "merge-joinable join conditions" mean ????