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

David Chang dchang at fsautomation.com
Mon Oct 5 18:54:07 EDT 2015


Dave,

I see you set the text size in the freetds.conf file to 1000000.  I 
would confirm it using 'select @@textsize'.

DC

On 10/5/2015 2:07 PM, Jacopille, David wrote:
> 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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