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>>I confirmed the UNION hack is no longer required. Thanks! Is it too late

Browse Source 
>>to change the README in contrib/dblink?
>>
>
> No, I don't think that's a problem.  Send a patch.
>

Here's a (documentation only) patch for the contrib/dblink README.

Joe Conway
This commit is contained in:
Bruce Momjian 2001-12-13 10:48:39 +00:00
parent ba578ae667
commit cde5fae7c9
1 changed files with 8 additions and 35 deletions
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43
contrib/dblink/README.dblink
View File

@ -82,7 +82,8 @@ Outputs
Example usage
select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd','select f1, f2 from mytable');
select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
,'select f1, f2 from mytable');
==================================================================
@ -118,44 +119,16 @@ Example usage
==================================================================
NOTE: If you need to provide selection criteria in a WHERE clause, it is necessary
to 'fake' a UNION, e.g.
A more convenient way to use dblink may be to create a view:
select
dblink_tok(t1.dblink_p,0) as f1
,dblink_tok(t1.dblink_p,1) as f2
from
(
select dblink(
'hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
,'select f1, f2 from mytable'
) as dblink_p
union all
select null where false
) as t1
where
dblink_tok(t1.dblink_p,0) = 'mycriteria';
in order to work around an issue with the query optimizer. A more convenient way to approach
this problem is to create a view:
create view myremotetable as
select
dblink_tok(t1.dblink_p,0) as f1
,dblink_tok(t1.dblink_p,1) as f2
from
(
select dblink(
'hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
,'select f1, f2 from mytable'
) as dblink_p
union all
select null where false
) as t1;
create view myremotetable as
select dblink_tok(t1.dblink_p,0) as f1, dblink_tok(t1.dblink_p,1) as f2
from (select dblink('hostaddr=127.0.0.1 port=5432 dbname=template1 user=postgres password=postgres'
,'select proname, prosrc from pg_proc') as dblink_p) as t1;
Then you can simply write:
select f1,f2 from myremotetable where f1 = 'mycriteria';
select f1, f2 from myremotetable where f1 like 'bytea%';
==================================================================