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FAQ
While trying to test out the "EXPLAIN and nfiltered, take two" patch
with its test file "explaintesti", I noticed I was getting a warning
message like:

WARNING: problem in alloc set ExecutorState: detected write past
chunk end in block 0x101134e00, chunk 0x101134f38

I got the same warning on unpatched git head as well. I was able to
reproduce the problem with the attached input.sql file, along with a
dummy input file, dummy_passwd, for the foreign table to read from. I
get the above warning along with:

ERROR: missing data for column "pass"
CONTEXT: COPY passwd, line 1: "##"
STATEMENT: SELECT * FROM passwd WHERE uid > 4;

The error message is not surprising, since I am feeding the foreign
table improperly-formatted lines. The warning is what concerns me;
from the comments in aset.c and the warning message text itself, I
gather this is not expected. I tested on OS X 10.6, with
--enable-cassert --enable-debug.

Josh

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  • Tom Lane at Sep 13, 2011 at 10:29 pm ⇧

    Josh Kupershmidt writes:
    While trying to test out the "EXPLAIN and nfiltered, take two" patch
    with its test file "explaintesti", I noticed I was getting a warning
    message like:
    WARNING: problem in alloc set ExecutorState: detected write past
    chunk end in block 0x101134e00, chunk 0x101134f38
    I got the same warning on unpatched git head as well.
    Can't reproduce that here, on either 32-bit or 64-bit hardware.
    However, this sort of issue is often exceedingly sensitive to
    environment and build options. What's your platform, what did you use
    for configure options, etc?

    [ thinks for a bit... ] It could easily also depend on the precise
    lengths of strings being pushed around. What's the exact length of
    the foreign table pathname you actually used? And is that the exact
    dummy file you used?

    regards, tom lane
  • Josh Kupershmidt at Sep 13, 2011 at 11:22 pm ⇧

    On Tue, Sep 13, 2011 at 6:29 PM, Tom Lane wrote:
    Josh Kupershmidt <[email protected]> writes:
    While trying to test out the "EXPLAIN and nfiltered, take two" patch
    with its test file "explaintesti", I noticed I was getting a warning
    message like:
    WARNING:  problem in alloc set ExecutorState: detected write past
    chunk end in block 0x101134e00, chunk 0x101134f38
    I got the same warning on unpatched git head as well.
    Can't reproduce that here, on either 32-bit or 64-bit hardware.
    However, this sort of issue is often exceedingly sensitive to
    environment and build options.  What's your platform, what did you use
    for configure options, etc?
    I got the warning on OS X 10.6 64-bit. The only configure options I
    used were --prefix=/path/ --enable-cassert --enable-debug.
    [ thinks for a bit... ]  It could easily also depend on the precise
    lengths of strings being pushed around.  What's the exact length of
    the foreign table pathname you actually used?  And is that the exact
    dummy file you used?
    I saw the warning first with my actual /etc/passwd file, which had
    those comment lines to trigger the error, while trying Marko's
    explaintesti sample file[1]. Then I reproduced the problem on git head
    with that dummy file at location
    "/Users/josh/pg_permanent/warning_alloc/dummy_passwd".

    FWIW, I can't reproduce the problem on a 64-bit Ubuntu 11.04 machine either.

    Josh
  • Tom Lane at Sep 13, 2011 at 11:39 pm ⇧

    Josh Kupershmidt writes:
    On Tue, Sep 13, 2011 at 6:29 PM, Tom Lane wrote:
    Can't reproduce that here, on either 32-bit or 64-bit hardware.
    However, this sort of issue is often exceedingly sensitive to
    environment and build options.  What's your platform, what did you use
    for configure options, etc?
    I got the warning on OS X 10.6 64-bit. The only configure options I
    used were --prefix=/path/ --enable-cassert --enable-debug.
    Hmm. I tried on 64-bit Lion (10.7.1) and had no luck.

    Please try setting a gdb breakpoint on the warning elog (it's in aset.c)
    and looking to see what's the contents of the complained-of chunk. That
    might give us a hint anyway ...

    regards, tom lane
  • Josh Kupershmidt at Sep 14, 2011 at 10:23 pm ⇧

    On Tue, Sep 13, 2011 at 7:38 PM, Tom Lane wrote:
    Hmm.  I tried on 64-bit Lion (10.7.1) and had no luck.

    Please try setting a gdb breakpoint on the warning elog (it's in aset.c)
    and looking to see what's the contents of the complained-of chunk.  That
    might give us a hint anyway ...
    D'oh. Looks like this was a false alarm; I think I neglected to
    recompile file_fdw.so to correspond to the server I was running. At
    least, the warning has gone away upon a rebuild of the file_fdw
    module. Sorry for the noise.

    Josh

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postedSep 13, '11 at 10:12p
activeSep 14, '11 at 10:23p
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