Обсуждение: Re: [BUGS] BUG #2444: XA Connections given by posgres driver has

Moving to -jdbc.

On Fri, 19 May 2006, Jagadish Prasath Ramu wrote:

> The following bug has been logged online:
>
> Bug reference:      2444
> Description:        XA Connections given by posgres driver has auto-commit
> value false by default
> Details:
>
> Problem with PostgresDriver : postgresql-8.1-405.jdbc3.jar
>
> I am using the above driver to get an XA Connection and I found that
> auto-commit value of it is false by default.
>
> Source : org/postgresql/xa/PGXAConnection.java
> Constructor :
>
> PGXAConnection(BaseConnection conn) throws SQLException
>    {
>        super(conn, false);
>        this.conn = conn;
>        this.conn.setAutoCommit(false);
>        this.state = STATE_IDLE;
>        this.logger = conn.getLogger();
>    }
>
>
>> From JDBC Specification 3.0, Chapter 10.1.1 > Disabling AutoCommit mode :
>
> " The default is for auto-commit mode to be enabled when the Connection
> object is
> created. If the value of auto-commit is changed in the middle of a
> transaction, the
> current transaction is committed. It is an error to enable auto-commit for
> a
> connection participating in a distributed transaction, as described in
> Chapter 12
> “Distributed Transactions”. "
>
> Chapter 12 > 12.4 Transaction Management :
> "In contrast to the local case, the boundaries of a
> distributed transaction must be controlled by an external transaction
> manager that is
> coordinating the work of multiple connections. For this reason, it is an
> error for
> applications to call any of the following Connection methods while they are
> participating in a distributed transaction:
> setAutoCommit(true)
> commit
> rollback
> setSavepoint
> The JDBC driver throws an SQLException if one of these operations is
> attempted
> on a connection that is participating in a distributed transaction. If the
> connection is
> later used for a local transaction, these operations are legal at that
> point."
>
>> From these excerpts what I could understand is auto-commit for XA's
> connection need to be true when created and auto-commit can not be set to
> true when a transaction in progress.
>

I'm not sure what the purpose of this is.  Why would you want a connection
to be in autocommit = true when this is a condition you are explicitly not
allowed to set yourself?

Kris Jurka

Hi Kris,
I am trying to use this XA-Connection without any transaction context.

eg: I have a test case using 2 XA-Connections on 2 different DBs and DB-operations go fine.
As a part of the test, I need to check whether the data is actually is persisted.
In this case,  I get a connection (XAConnection) from the datasource and do a query. This connection's auto-commit value is false.
According to the JDBC 3.0 Specification, auto-commit need to be true when created.  [ my case ]
Only when the connection is taking part in a transaction, setting auto-commit value is not allowed.

Since I am using the connection without any transaction context,  auto-commit need to be true in this case according to the specification.

Thanks,
-Jagadish

On Mon, 2006-05-22 at 15:14 -0500, Kris Jurka wrote:

Moving to -jdbc.

On Fri, 19 May 2006, Jagadish Prasath Ramu wrote:

> The following bug has been logged online:
>
> Bug reference:      2444
> Description:        XA Connections given by posgres driver has auto-commit
> value false by default
> Details:
>
> Problem with PostgresDriver : postgresql-8.1-405.jdbc3.jar
>
> I am using the above driver to get an XA Connection and I found that
> auto-commit value of it is false by default.
>
> Source : org/postgresql/xa/PGXAConnection.java
> Constructor :
>
> PGXAConnection(BaseConnection conn) throws SQLException
>    {
>        super(conn, false);
>        this.conn = conn;
>        this.conn.setAutoCommit(false);
>        this.state = STATE_IDLE;
>        this.logger = conn.getLogger();
>    }
>
>
>> From JDBC Specification 3.0, Chapter 10.1.1 > Disabling AutoCommit mode :
>
> " The default is for auto-commit mode to be enabled when the Connection
> object is
> created. If the value of auto-commit is changed in the middle of a
> transaction, the
> current transaction is committed. It is an error to enable auto-commit for
> a
> connection participating in a distributed transaction, as described in
> Chapter 12
> “Distributed Transactions”. "
>
> Chapter 12 > 12.4 Transaction Management :
> "In contrast to the local case, the boundaries of a
> distributed transaction must be controlled by an external transaction
> manager that is
> coordinating the work of multiple connections. For this reason, it is an
> error for
> applications to call any of the following Connection methods while they are
> participating in a distributed transaction:
> setAutoCommit(true)
> commit
> rollback
> setSavepoint
> The JDBC driver throws an SQLException if one of these operations is
> attempted
> on a connection that is participating in a distributed transaction. If the
> connection is
> later used for a local transaction, these operations are legal at that
> point."
>
>> From these excerpts what I could understand is auto-commit for XA's
> connection need to be true when created and auto-commit can not be set to
> true when a transaction in progress.
>

I'm not sure what the purpose of this is.  Why would you want a connection 
to be in autocommit = true when this is a condition you are explicitly not 
allowed to set yourself?

Kris Jurka

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Jagadish Prasath Ramu wrote:
> In this case,  I get a connection (XAConnection) from the datasource
> and do a query. This connection's auto-commit value is false.
> According to the JDBC 3.0 Specification, auto-commit need to be true
> when created.  [ my case ]
> Only when the connection is taking part in a transaction, setting
> auto-commit value is not allowed.
>
> Since I am using the connection without any transaction context,
> auto-commit need to be true in this case according to the
> specification.

The auto-commit mode is specified to be ignored for any connection that is
participating in a non-local transaction.  Hence, it doesn't matter whether
auto-commit is true or false in the situation you're talking about.  The
behavior is always as if auto-commit is false.

It does seem, though, that the flag should be set to false in order to
comply by-the-letter, as useless as that is.

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