Re: Comparing two tables of different database

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От Lucas Brito
Тема Re: Comparing two tables of different database
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Msg-id cccdaefb0905021425y597c31ecq2baae0748800076d@mail.gmail.com
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Ответ на Fwd: Comparing two tables of different database  (Isaac Dover <isaacdover@gmail.com>)
Ответы Re: Comparing two tables of different database
Список pgsql-sql
2009/5/2 Isaac Dover <isaacdover@gmail.com>
i've not tried this in postgres, but using information_schema makes comparing structures of databases trivial. i've been using this query for a while with MSSQL. Maybe this helps to answer the question.
 
- isaac
 
select ST.Table_Name, ST.Column_Name, DV.Table_Name, DV.Column_Name, *
from [database].information_schema.Columns ST
full outer join [other database].information_schema.Columns DV
on ST.Table_Name = DV.Table_name
and ST.Column_Name = DV.Column_Name
where ST.Column_Name is null or DV.Column_Name is NULL
 

Isaac, this query will return "ERROR:  cross-database references are not implemented".

Postgres does not support queries in databases other than current one. Even a simple select * from otherdatabase.information_schema.columns will not work and throw the same error.

However this can be done with dblink function like:

select ST.Table_Name, ST.Column_Name, DV.Table_Name, DV.Column_Name, *
from information_schema.Columns ST
full outer join dblink('dbname=otherdatabase','select Table_Name, Column_Name from information_schema.Columns') DV(Table_Name text, Column_Name text)
on ST.Table_Name = DV.Table_name
and ST.Column_Name = DV.Column_Name
where ST.Column_Name is null or DV.Column_Name is NULL

--
Lucas Brito

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