Re: odbc_lob_read chunk is short

Martin Gainty wrote:
> "odbc_lob_read(sth, colno, buf, length, \%attrs)
> where \%attrs can contain TYPE => SQL_type."
>
> http://www.nntp.perl.org/group/perl.dbi.dev/2010/07/msg6140.html
>
> where Type should be SQLBINARY
> http://www.nntp.perl.org/group/perl.dbi.dev/2010/09/msg6258.html

Thanks Martin,

Sorry, disregard my previous erroneous email; here's the corrected:

I've tried various incantations ...

$s->odbc_lob_read(1, \my $x, 8, {TYPE => 'SQL_BINARY'})
$s->odbc_lob_read(1, \my $x, 8, {TYPE => 'SQL_C_BINARY'})
$s->odbc_lob_read(1, \my $x, 8, {TYPE => 'SQLBINARY'})
odbc_lob_read($s, 1, \my $x, 8, {TYPE => 'SQL_BINARY'})
odbc_lob_read($s, 1, \my $x, 8, {TYPE => 'SQL_C_BINARY'})
odbc_lob_read($s, 1, \my $x, 8, {TYPE => 'SQLBINARY'})

... and the result is the same - 7 bytes are in the buffer, while the
amount yet to be read is reduced by 8.

> "It turns out I was mistaken as DBD::Oracle DOES implement blob read
> although I've not tested it works. Someone, in the distant past
> attempted an implementation in DBD::ODBC but it does NOT work and is
> seriously flawed."
> http://www.nntp.perl.org/group/perl.dbi.dev/2010/07/msg6144.html

Sorry for being thick - are you saying reading the BLOB in chunks just
isn't going to work?


I see in the trace file that ODBC thinks the type is "LONG VARBINARY"; I
set the type to SQL_BINARY in the call to odbc_lob_read:

DescribeCol column = 1, name = ATTACHMENT, namelen = 10, type = LONG
VARBINARY(-4), precision/column size = 2147483647, scale = 0, nullable = 1
     SQL_COLUMN_DISPLAY_SIZE = 2147483647
     SQL_COLUMN_LENGTH = 2147483647
     now using col 1: type = LONG VARBINARY (-4), len = 2147483647,
display size = 80, prec = 2147483647, scale = 0
    -dbd_describe done_bind=0
    have 1 fields
    -dbd_st_execute(f45808)=-1
    <- execute= ( -1 ) [1 items] at /root/lob_read.pl line 28
    >> bind_col    DISPATCH (DBI::st=HASH(0x10f4920) rc1/1 @4 g2 ima1
pid#13491) at /root/lob_read.pl line 29
    -> bind_col for DBD::ODBC::st (DBI::st=HASH(0x10f4920)~0x10f49b0 1
undef HASH(0x10f53e8)) thr#da2010
  bind_col 1 requested type:0, flags:100

-- Mike