Behaviour of setAutoCommit may not be completely correct.

Hello.

I found a situation that is causing db locks using enhydra dods with postgresql due to somethinf that look like a bad behaviour of postgresql.
Since version 6.0, i think, dods do all the db queries with setAutoCommit(false). The expected behaviour of setAutocommit(...) is that the current transaction is commited, allowing the db backend to free resources previously allocated, and a new one is created with the autocommit set to the value passed.

From the specs: "If the value of auto-commit is changed in the middle of a transaction, the current transaction is committed."

The postgresql have a problem with setAutocommit(...): if the value passed (false or true) is the same that was previously set, it just does nothing.

I looked to the postgresql driver and found this:

public void setAutoCommit(boolean autoCommit) throws SQLException
{
if (this.autoCommit == autoCommit)
return ;
if (autoCommit)
{
execSQL("end");
}
else
{
if (haveMinimumServerVersion("7.1"))
{
execSQL("begin;" + getIsolationLevelSQL());
}
else
{
execSQL("begin");
execSQL(getIsolationLevelSQL());
}
}
this.autoCommit = autoCommit;
}

The driver do nothing when the value passed (false or true) is the same
that was previously set.
I fixed the driver and found that the behaviour was the same: it's look
likes the backend is using the same logic and that explain why someone
at the driver JDBC decided to not pass this to the backend.
My tests were done with Postgresql 7.4.12.
Can someone confirm that the problem exist and it is in the driver code
and the backend server?
Is this still happening with postgresql 8.1?

Best regards
João Paulo Ribeiro

--
João Paulo Ribeiro | Senior Software Engineer
jp(at)mobicomp(dot)com

PHONE: + 351 253 305 250
FAX : + 351 253 305 250
www.mobicomp.com

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