Обсуждение: Transaction Queries!!!

On Tue, 14 Oct 2003, Vatsal wrote:

> We are using postgresql as the underlying RDBMS for one of our
>  application. When in a transaction if we execute an query that causes
>  database to return a failure. The whole transaction gets roll backed.
Yes, all errors are treated as unrecoverable, so you're forced to roll the
transaction back.  At some point nested transactions or savepoints will
let you have more control.

>  A another problem is of executing update query thru ODBC API's. When we
>  run update query thru executeQuery() API, even though the update query
> may
>  not go thru as some column condition may not have met or the where
> clause
>  may have been wrong. In such case also the API returns success.
>
>  When the query is executed thru psql prompt it says zero rows updated.
>  Has this problem got to do with postgresql or ODBC API?

An update that updates no rows is still a success by our general
definition.

On Tue, 14 Oct 2003, Vatsal wrote:

> We are using postgresql as the underlying RDBMS for one of our
>  application. When in a transaction if we execute an query that causes
>  database to return a failure. The whole transaction gets roll backed.
Yes, all errors are treated as unrecoverable, so you're forced to roll the
transaction back.  At some point nested transactions or savepoints will
let you have more control.

>  A another problem is of executing update query thru ODBC API's. When we
>  run update query thru executeQuery() API, even though the update query
> may
>  not go thru as some column condition may not have met or the where
> clause
>  may have been wrong. In such case also the API returns success.
>
>  When the query is executed thru psql prompt it says zero rows updated.
>  Has this problem got to do with postgresql or ODBC API?

An update that updates no rows is still a success by our general
definition.

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On Wed, Oct 15, 2003 at 10:37:27AM +0530, Vatsal wrote:

> could you please elaborate or give me some pointers on Nested
> Transactions or Savepoints( which you are talking about in your reply to
> the first problem)

Nested transactions are not implemented in Postgres, and won't be in the
next release 7.4.  Neither are savepoints.

--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"Es filósofo el que disfruta con los enigmas" (G. Coli)