Re: Append table - Mailing list pgsql-performance

There are two solutions:
You can insert all data from tableB in tableA using a simple insert
select-statement like so:
INSERT INTO tabelA SELECT EmpId, EmpName FROM tabelB;

Or you can visually combine them without actually putting the records in
a single table. That can be with a normal select-union statement or with
a view, something like this:
SELECT EmpId, EmpName FROM tabelA UNION EmpID, EmpName FROM tabelB;

You can use this query as a table-generating subquery in a FROM-clause,
like so:

SELECT * FROM (SELECT EmpId, EmpName FROM tabelA UNION EmpID, EmpName
FROM tabelB) as emps WHERE EmpId = 1;

Or with the view:
CREATE VIEW tabelC AS SELECT EmpId, EmpName FROM tabelA UNION EmpID,
EmpName FROM tabelB;

And then you can use the view as if it was a normal table (altough
inserts are not possible without applying rules to them, see the manual
for that).

SELECT * FROM tabelC WHERE EmpId = 1;

Best regards,

Arjen

On 2-6-2007 17:52 Hanu Kurubar wrote:
> Any luck on appending two table in PostgreSQL.
> Below are two table with same schema that have different values. In this
> case EmpID is unique value.
>
> tabelA
> ------------
> EmpId (Int) EmpName (String)
> 1               Hanu
> 2               Alvaro
>
>
> tabelB
> ------------
> EmpId (Int) EmpName (String)
> 3               Michal
> 4               Tom
>
>
> I would be looking below output after appending tableA with tableB. Is
> this possible in PostgreSQL?
>
>
> tabelA
> ------------
> EmpId (Int) EmpName (String)
> 1               Hanu
> 2               Alvaro
> 3               Michal
> 4               Tom
>
>
>
> Thanks,
> Hanu
>
>
> On 5/30/07, *Hanu Kurubar* <hanu.kurubar@gmail.com
> <mailto: hanu.kurubar@gmail.com>> wrote:
>
>     Can you help me appending two table values into single table without
>     performing INSERT?
>     Note that these tables are of same schema.
>
>     Is there any sql command is supported?
>
>     Thanks,
>     Hanu
>
>
>     On 5/29/07, *Alvaro Herrera* <alvherre@commandprompt.com
>     <mailto:alvherre@commandprompt.com>> wrote:
>
>         Michal Szymanski wrote:
>          > There is another strange thing. We have two versions of our test
>          > >>environment one with production DB copy and second
>         genereated with
>          > >>minimal data set and it is odd that update presented above
>         on copy of
>          > >>production is executing 170ms but on small DB it executing
>         6s !!!!
>          > >
>          > >How are you vacuuming the tables?
>          > >
>          > Using pgAdmin (DB is installed on my laptop) and I use this
>         tool for
>          > vaccuminh, I do not think that vaccuming can help because
>         I've tested on
>          > both database just after importing.
>
>         I think you are misunderstanding the importance of vacuuming the
>         table.
>         Try this: on a different terminal from the one running the test,
>         run a
>         VACUUM on the updated table with vacuum_cost_delay set to 20, on an
>         infinite loop.  Keep this running while you do your update
>         test.  Vary
>         the vacuum_cost_delay and measure the average/min/max UPDATE times.
>         Also try putting a short sleep on the infinite VACUUM loop and
>         see how
>         its length affects the UPDATE times.
>
>         One thing not clear to me is if your table is in a clean
>         state.  Before
>         running this test, do a TRUNCATE and import the data
>         again.  This will
>         get rid of any dead space that may be hurting your measurements.
>
>         --
>         Alvaro
>         Herrera                        http://www.advogato.org/person/alvherre
>         "The Postgresql hackers have what I call a "NASA space shot"
>         mentality.
>         Quite refreshing in a world of "weekend drag racer" developers."
>         (Scott Marlowe)
>
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>
>
>
>     --
>     With best regards,
>     Hanumanthappa Kurubar
>     Mobile: 98 801 800 65
>
>
>
>
> --
> With best regards,
> Hanumanthappa Kurubar
> Mobile: 98 801 800 65