Re: odbc_lob_read chunk is short

On 05/09/13 20:28, Mike Grau wrote:
> Hello,
>
> I am completely new at this, but I am trying to read a BLOB in chunks
> via ODBC in Oracle 11g using DBD::ODBC-1.43, unixODBC-2.3.1 and
> oracle-instantclient11.2-odbc-11.2. I can read an entire BLOB in one
> read and write it to the filesystem, but I really need to be able to do
> it in chunks, I think.
>
> Reading the BLOB in chunks, but I am always getting one byte less than
> requested, losing the last byte, which results in a corrupt document (a
> PDF) when written to the filesystem. I'm at a loss as to why this is
> happening and how to correct it.
>
> Using this snippet based on the example provided by DBD::ODBC...
>
> while($len = $s->odbc_lob_read(1, \my $x, 8, {TYPE => 999})) {
>      print "len=$len, x=$x\n";
> }
>
> ... produces this output:
>
> len=7, x=435886
> len=7, x=0000 n
> len=7, x=0001282
> len=7, x=60 0000
>
> And a tracefile shows the same.
>
> SQLGetData(col=1,type=-2)=1 (retlen=2046252)
>   <- odbc_lob_read= ( 7 ) [1 items] at /root/lob_read.pl line 45
>   >> odbc_lob_read DISPATCH (DBI::st=HASH(0x203c940) rc1/1 @5 g2 ima0
> pid#11494) at /root/lob_read.pl line 45
>   -> odbc_lob_read for DBD::ODBC::st (DBI::st=HASH(0x203c940)~0x203c9d0 1
> SCALAR(0x1e0a440) 8 HASH(0x203c970)) thr#1cea010
> SQLGetData(col=1,type=-2)=1 (retlen=2046244)
>   <- odbc_lob_read= ( 7 ) [1 items] at /root/lob_read.pl line 45
>   >> odbc_lob_read DISPATCH (DBI::st=HASH(0x203c940) rc1/1 @5 g2 ima0
> pid#11494) at /root/lob_read.pl line 45
>   -> odbc_lob_read for DBD::ODBC::st (DBI::st=HASH(0x203c940)~0x203c9d0 1
> SCALAR(0x1e0a440) 8 HASH(0x203c9a0)) thr#1cea010
>
> Can someone please give me some guidance how to get the full chunk
> requested?
>
> I'm using
>    unixODBC-2.3.1 - built from the tarball
>    DBD-ODBC-1.43  - installed from the tarball (perl Makefile.PL; make;
>    make install)
>    oracle-instantclient11.2-odbc-11.2.0.3 installed from RPM
>    DBI is the distro's perl-DBI-1.617-4.1.1.x86_64 (openSUSE 12.3)
>    The database and client are both x86_64
>
> The instant client is link against libodbcinst.so.1 and unixODBC now
> provides libodbcinst.so.2, so I symlinked them:
> libodbcinst.so.1 -> /usr/local/lib64/libodbcinst.so.2
> Ugly, but seems to work.
>
> Ultimately I want to index documents stored in Oracle with Sphinx and so
> must use ODBC. I'd like to know that this much is working before moving
> on to Sphinx.
>
> TIA -- Mike G.
>

Bear with me and I'll take another look at that code. If I cannot see anything I might need to send you a new version with slightly different logging. By all means nag me if I don't get back to you by tomorrow.

Martin
-- 
Martin J. Evans
Easysoft Limited
http://www.easysoft.com