Re: [sqlite] question on WAL files

[Dan Kennedy]

On 09/20/2013 11:30 PM, Carey, John wrote:
Hello,
I am trying to write a simple perl program (perl version 5.16.3). I am 
accessing a SQLite db which is using WAL(write ahead logging). It took me a 
while but I learned that my connection is only looking at the DB file and not 
the WAL file. As a result, my queries are not returning the full data set.

the SQLite firefox addon shows 10 invoices in the invoice table. the following 
program is returning only 8...

use DBD::SQLite;
use DBI;
use Tkx;
use File::Copy;
use PDF::API2;
use constant mm => 25.4 / 72;
use constant in => 1 / 72;
use constant pt => 1;

# Prompt user for database file location

$dbfile = Tkx::tk___getOpenFile(-initialdir=>'C:/events_p', -title=>'Please 
select your current events database file (event.sqlite)');
$dbfile =~ s/\//\\/g;

# Initialiatize path variables
# parse out the db filename and path
$DbFilename=substr($dbfile,length($dbfile)-12,12);
$FolderPath=substr($dbfile,0,length($dbfile)-13);
$OriginalImages_Path=$FolderPath.\\OriginalImages;
$Internal_Path=$FolderPath.\\_internal;
$Carts_Path=$FolderPath.\\Carts;
$Orders_Path=$FolderPath.\\Orders;
$favorites="c:\favorites";
$Invoices_Folder="C:\\events_p_invoices";

# Error and exit if incorrect DB filename was selected
if ($DbFilename ne 'event.sqlite')
{
     print "\n**** ERROR ****, Invalid Database Filename Selected\n";
     print "      You MUST select the filename called  event.sqlite\n";
     sleep(10);
     exit;
}

# Connect to the Database
my $dbh2 = DBI->connect("dbi:SQLite:$dbfile", "", "",{RaiseError => 1, AutoCommit 
=> 1}) or die $DBI::errstr;;
$dbh2->do('PRAGMA journal_mode=WAL');
my $sth = $dbh2->prepare("SELECT count(*) fromInvoice");

$sth->execute();
   while (@data = $sth->fetchrow_array())
  {
       print "count=$data[0]\n";
  }

exit;

If I go into the firefox add on and run a checkpoint , the 2 new invoices get 
flushed from the WL to the db file and then my program sees them
what am I doing wrong where my script is only looking at the db file and not 
the WAL file?

Are there multiple links in the file-system to the database file?

More information in section 2.5 here: 
http://www.sqlite.org/howtocorrupt.html

Dan.



thanks!

John
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users