Difference between 7.2 and 7.3, possible bug?

Barry Lind <barry@xythos.com> writes:

create table test (col_a bigint);
update test set col_a = nullif('200', -1);
The above works fine on 7.2 but the update fails on 7.3b2 with the
following error:
ERROR: column "col_a" is of type bigint but expression is of type text
You will need to rewrite or cast the expression

Is this change in behavior intentional or is it a bug?

This is an intentional tightening of implicit-cast behavior.

This situation is occuring because of two changes. The first being the
difference in how the server is handling the above update in 7.2 vs.
7.3. The second is a change in the jdbc driver in 7.3. The actual
update in jdbc looks like:
update test set col_a = nullif(?, -1);
and a "setLong(1, 200)" call is being done. In 7.2 the jdbc driver
bound the long/bigint value as a plain number, but in 7.3 it binds it
with quotes making it type text and exposing the change in server
behavior.

I would say that that is a very bad decision in the JDBC driver and
should be reverted ... especially if the driver is not bright enough
to notice the context in which the parameter is being used. Consider
for example

regression=# select 12 + 34;
?column?
----------
46
(1 row)

regression=# select '12' + '34';
?column?
----------
d
(1 row)

Not exactly the expected result ...

2) revert the jdbc driver back to not quoting int2 and int8 values
- If the server now handles using indexes on int2/int8 columns then
this should be done anyway
- It the server still has problems with using indexes without the
quotes then this removes an often requested bugfix/workaround
for the index usage problem

You are trying to mask a server problem in the driver. This is not a
good idea. The server problem is short-term (yes, we've finally agreed
how to fix it, and it will happen in 7.4), but a client-library hack to
mask it will cause problems indefinitely.

regards, tom lane

Tom Lane wrote:

I would say that that is a very bad decision in the JDBC driver and
should be reverted ... especially if the driver is not bright enough
to notice the context in which the parameter is being used. Consider
for example

...

You are trying to mask a server problem in the driver. This is not a
good idea. The server problem is short-term (yes, we've finally agreed
how to fix it, and it will happen in 7.4), but a client-library hack to
mask it will cause problems indefinitely.

regards, tom lane

Tom,

Thanks for the quick reply. I will back out the jdbc change. It was
one of those changes I did reluctantly. I have been pushing back for a
couple of releases now saying that this is a server bug and needs to be
fixed there. But it didn't seem like that was ever going to happen so I
finally gave in. For some users this bug of not using indexes for
int2/int8 makes it impossible for them to use postgres. This happens
for users who are using a database abstraction layer that doesn't allow
the user to actually touch the sql being sent to the server. Therefore
they have no opportunity to work around the underlying bug and can't use
postgres as their database because of the performance problems.

I am glad to here this is finally getting resolved for 7.4.

thanks,
--Barry