pgsql/src/interfaces/libpgtcl pgtclId.c - Mailing list pgsql-committers

From Marc G. Fournier
Subject pgsql/src/interfaces/libpgtcl pgtclId.c
Date
Msg-id 200109072155.f87Lt0m78056@hub.org
Whole thread Raw
List pgsql-committers
CVSROOT:    /home/projects/pgsql/cvsroot
Module name:    pgsql
Changes by:    scrappy@hub.org    01/09/07 17:55:00

Modified files:
    src/interfaces/libpgtcl: pgtclId.c

Log message:
    >has anyone ever successfully done copy to/from stdout with the
    >tcl-extension for postgreSQL.
    >I'm currently using 7.0 and always getting a seg fault when I try to
    >read from the database connection after issueing a "COPY table TO
    >stdout;" (I'm using the connection handle, *not* the result handle).
    >Maybe this is fixed in a later release.
    >The README file in src/interfaces/libpgtcl tells me, that this should
    >work, but unforunately it doesn't.

    Yes, it seems broken. It is a bug in libpgtcl.  Are you running Tcl >= 8.3.2?
    That's when the Tcl team changed the data structure for channel
    callbacks.  The change itself was designed to be backward compatible, but I
    suspect a related change made the code more sensitive to errors in the
    structure (NULL pointers where functions are required).  Either that, or
    nobody has tried to use libpgtcl with COPY in a long time.

    First, I have to say I can't think of a good reason to use PostgreSQL's
    COPY command from a Tcl application. I think it should only be used with
    psql for importing data from another source into PostgreSQL, or for
    exporting PostgreSQL data into another database (but why would anyone do
    that?) If it was me, I would stick with SELECT and INSERT and be "SQL
    Compliant".

    OK, editorial is over. Try applying the patch below to fix
    src/interfaces/libpgtcl/pgtclId.c
    and let us know if it works. I did little testing on it, but my test did
    segfault before and ran fine (copy in and copy out) after the patch.  This
    is for PostgreSQL-7.1.2 - since you are running older 7.0, I don't know if
    this will work, but I suspect it will.

    PS It's the absence of PgWatchProc which kills it. I didn't upgrade it
    to the "V2" channel type structure, so it should be compatible with older
    Tcl's. But aside from gets and puts, I doubt any other file operations
    would work on the handle during a copy.

    ljb


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