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freetds - [freetds] Using FreeTDS 0.95 INSERTS fail above 66000 characters...unless 'dump file' is turned on

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  • From: "Jacopille, David" <DJacopille AT MFS.com>
  • To: "freetds AT lists.ibiblio.org" <freetds AT lists.ibiblio.org>
  • Cc: "Chavez, Emmanuel" <EChavez AT MFS.com>
  • Subject: [freetds] Using FreeTDS 0.95 INSERTS fail above 66000 characters...unless 'dump file' is turned on
  • Date: Mon, 5 Oct 2015 21:07:02 +0000

Looking for suggestions or a troubleshooting approach on this 100%
reproducible issue where FreeTDS logging seems to be the only variable.

Since the issue goes away as soon as I turn on freetds logging I can¹t
look at the logs to find the problem.

ENVIRONMENT
SQL Server 2012
OS X 10.9.5
FreeTDS 0.95.20
DBD::Sybase 1.15
TDSVER 7.0 or 7.1 (same symptoms)
Perl 5.16.3
FreeTDS text size = 1000000

Testing large string INSERTS to a table with a single, nvarchar(max),
column


WHAT WORKS
A. With freetds logging on (via 'dump file = /tmp/freetds.log¹) INSERT
values from 0-500,000 characters are successful. Decreasing reliability
above 500,000 characters.

B. INSERT statements with values of 0 thru 66,000 characters always work,
regardless of freetds logging on/off

C. SELECT work correctly for all values 0 thru one million characters,
regardless of freetds logging on/off


DOES NOT WORK
If freetds logging is turned off the following fails consistently:

A. 67,000 character INSERT stalls at INSERT

B. 100,000+ character INSERT doesn¹t stall but doesn¹t INSERT

C. Stored Procedures also experiencing failures in same character ranges


FREETDS.CONF

# In the failure configuration it looks like this.
# The ³DOES NOT WORK² symptoms go away if the last two lines are
uncommented.

[global]
client charset = UTF-8
text size = 1000000

[bossqld4]
host = bossqld4.mfs.com
port = 1433
tds version = 7.0
#dump file = /tmp/freetds.log
#dump file append = no


PERL SCRIPT REPRODUCING ISSUE (WITH NO FREETDS LOGGING)

use DBI qw(:sql_types);
use DBD::Sybase;
my ($sql, $dbh, $ref, $largetext);

$dbh = DBI->connect( 'DBI:Sybase:server=bossqld4', ŒCORP\user',
Œpassword', { PrintError => 0 } ) or die;
$dbh->do('use testdatabase');

$largetext = 'x' x 100000; # one hundred thousand characters

$dbh->do(qq|INSERT into TESTTABLE (maxtext) values (N\'$largetext\')|);

# SELECT not affected by FreeTDS logging on/off
# SELECT always successful on all values tested up to one million
characters (and probably much larger, but untested).

$sql = q|SELECT TOP 1 [maxtext] FROM TESTTABLE|;
$ref = $dbh->selectrow_arrayref($sql);
print 'Length of value: '. (length $$ref[0]) ."\n";

$dbh->disconnect();


Thank you,
Dave Jacopille
Boston

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