merge-join for domain with underlying type text - Mailing list pgsql-sql

From Randall Lucas
Subject merge-join for domain with underlying type text
Date
Msg-id 0ED09669-832B-11D7-B164-000A957653D6@tercent.net
Whole thread Raw
In response to Re: Using psql to insert character codes  (Randall Lucas <rlucas@tercent.net>)
Responses Re: merge-join for domain with underlying type text  (Rod Taylor <rbt@rbt.ca>)
List pgsql-sql
Hi Folks,

If I have a domain defined with an underlying type of "text" or 
"varchar," and I need to FULL OUTER JOIN two tables based upon the 
similarity in these fields, I am getting:

ERROR:  FULL JOIN is only supported with mergejoinable join conditions

I have looked at the docs and it seems that it's a matter of making the 
comparison operators for the domain type (as per SQL Reference :: 
"CREATE OPERATOR" section).  However, is there anything tricky about 
adding the merge-join capability to a domain?  Is there a preferred 
method?  Am I barking entirely up the wrong tree (could I, for example, 
use a casting trick?  Simply recasting the fields as type "text" 
doesn't avoid the error)?

Postgres version is 7.3.

Best,

Randall



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