Thread: PQendcopy error in multithreading

Hi,
        I am trying to update multiple tables using the 'PQputline/PQendcopy' function. The code works fine if the tables are updated one after the other.
However, if there are multiple threads trying to copy data into different tables, the function fails. i.e. if one thread has started its copy operation and if some other thread also starts its copy operation (on different table), one of them fails.
Strangely, the PQputline function is successful for both the threads after the end delimiter is sent (\.).
What might be the reason for this PQendcopy failure? How do I get the exact error message after the failure?

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Durgaprasad Pawar wrote:
> Hi,
>         I am trying to update multiple tables using the
> 'PQputline/PQendcopy' function. The code works fine if the tables are
> updated one after the other.
> However, if there are multiple threads trying to copy data into
> different tables, the function fails. i.e. if one thread has started its
> copy operation and if some other thread also starts its copy operation
> (on different table), one of them fails.
> Strangely, the PQputline function is successful for both the threads
> after the end delimiter is sent (\.).
> What might be the reason for this PQendcopy failure? How do I get the
> exact error message after the failure?

Are you trying to do this using the same connection in different
threads, or does each thread have its own connection?  I suspect you are
trying to do the former.

Sean

Durgaprasad Pawar wrote:
> Hey ! Thanks a lot !! It gave me an error message as follows:
>
> Error : ERROR:  new row for relation "****_06032007" violates check
> constraint "****_06032007_date_range_check
>
> Seems like one of my threads is trying to insert a record of some date
> into a table of other date.
>
> How do I make these messages appear on the NOVICE list? Your reply
> appears on the list. However, mine doesn't.

Not sure what the problem might be for you.  But I am glad you got the
error message you needed.

Sean


>
> */Sean Davis <sdavis2@mail.nih.gov>/* wrote:
>
>     Durgaprasad Pawar wrote:
>     > No. I am using different connections in different threads. Each thread
>     > is given a separate connection from a pool of connections at the
>     > beginning of its execution.
>
>     Great. So the next thing to figure out is what error is being
>     generated. From the Postgres docs for PQendcopy:
>
>     "...The return value is 0 on successful completion, nonzero otherwise.
>     (Use PQerrorMessage to retrieve details if the return value is
>     nonzero.)"
>
>     Hope that does it for you.
>
>     Sean
>
>
>
>     > */Sean Davis /* wrote:
>     >
>     > Durgaprasad Pawar wrote:
>     > > Hi,
>     > > I am trying to update multiple tables using the
>     > > 'PQputline/PQendcopy' function. The code works fine if the
>     tables are
>     > > updated one after the other.
>     > > However, if there are multiple threads trying to copy data into
>     > > different tables, the function fails. i.e. if one thread has
>     > started its
>     > > copy operation and if some other thread also starts its copy
>     operation
>     > > (on different table), one of them fails.
>     > > Strangely, the PQputline function is successful for both the threads
>     > > after the end delimiter is sent (\.).
>     > > What might be the reason for this PQendcopy failure? How do I
>     get the
>     > > exact error message after the failure?
>     >
>     > Are you trying to do this using the same connection in different
>     > threads, or does each thread have its own connection? I suspect
>     you are
>     > trying to do the former.
>     >
>     > Sean
>     >
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