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unlike template0 and template1 does not have any special status in terms of backend functionality. However, all external utilities such as createuser and createdb now connect to "postgres" instead of template1, and the documentation is changed to encourage people to use "postgres" instead of template1 as a play area. This should fix some longstanding gotchas involving unexpected propagation of database objects by createdb (when you used template1 without understanding the implications), as well as ameliorating the problem that CREATE DATABASE is unhappy if anyone else is connected to template1. Patch by Dave Page, minor editing by Tom Lane. All per recent pghackers discussions.
121 lines
3.0 KiB
Plaintext
121 lines
3.0 KiB
Plaintext
==================================================================
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Name
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dblink -- Returns a set from a remote database
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Synopsis
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dblink(text connstr, text sql [, bool fail_on_error])
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dblink(text connname, text sql [, bool fail_on_error])
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dblink(text sql [, bool fail_on_error])
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Inputs
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connname
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connstr
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If two arguments are present, the first is first assumed to be a specific
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connection name to use. If the name is not found, the argument is then
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assumed to be a valid connection string, of standard libpq format,
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e.g.: "hostaddr=127.0.0.1 dbname=mydb user=postgres password=mypasswd"
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If only one argument is used, then the unnamed connection is used.
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sql
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sql statement that you wish to execute on the remote host
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e.g. "select * from pg_class"
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fail_on_error
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If true (default when not present) then an ERROR thrown on the remote side
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of the connection causes an ERROR to also be thrown locally. If false, the
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remote ERROR is locally treated as a NOTICE, and no rows are returned.
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Outputs
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Returns setof record
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Example usage
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select * from dblink('dbname=postgres','select proname, prosrc from pg_proc')
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as t1(proname name, prosrc text) where proname like 'bytea%';
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proname | prosrc
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------------+------------
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byteacat | byteacat
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byteaeq | byteaeq
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bytealt | bytealt
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byteale | byteale
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byteagt | byteagt
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byteage | byteage
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byteane | byteane
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byteacmp | byteacmp
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bytealike | bytealike
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byteanlike | byteanlike
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byteain | byteain
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byteaout | byteaout
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(12 rows)
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select dblink_connect('dbname=postgres');
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dblink_connect
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----------------
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OK
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(1 row)
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select * from dblink('select proname, prosrc from pg_proc')
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as t1(proname name, prosrc text) where proname like 'bytea%';
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proname | prosrc
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------------+------------
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byteacat | byteacat
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byteaeq | byteaeq
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bytealt | bytealt
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byteale | byteale
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byteagt | byteagt
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byteage | byteage
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byteane | byteane
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byteacmp | byteacmp
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bytealike | bytealike
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byteanlike | byteanlike
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byteain | byteain
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byteaout | byteaout
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(12 rows)
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select dblink_connect('myconn','dbname=regression');
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dblink_connect
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----------------
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OK
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(1 row)
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select * from dblink('myconn','select proname, prosrc from pg_proc')
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as t1(proname name, prosrc text) where proname like 'bytea%';
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proname | prosrc
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------------+------------
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bytearecv | bytearecv
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byteasend | byteasend
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byteale | byteale
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byteagt | byteagt
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byteage | byteage
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byteane | byteane
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byteacmp | byteacmp
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bytealike | bytealike
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byteanlike | byteanlike
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byteacat | byteacat
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byteaeq | byteaeq
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bytealt | bytealt
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byteain | byteain
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byteaout | byteaout
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(14 rows)
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==================================================================
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A more convenient way to use dblink may be to create a view:
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create view myremote_pg_proc as
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select *
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from dblink('dbname=postgres','select proname, prosrc from pg_proc')
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as t1(proname name, prosrc text);
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Then you can simply write:
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select * from myremote_pg_proc where proname like 'bytea%';
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