Re: [sqlite] Understanding database lock

[Akash Rao]

Roger,

Thanks. I have read this a few times. But, i am trying to figure out how the
perl DBI for sqlite works with Sqlite's lock.

Any perl gurus here, please help.

Thanks,
Akash

On Wed, Nov 11, 2009 at 12:42 PM, Roger Binns rog...@rogerbinns.com wrote:

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 Akash Rao wrote:
  Wanted to understand the sqlite database lock a little better.

 Read this:

  http://www.sqlite.org/lockingv3.html

 Roger
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[sqlite] Understanding database lock

[Akash Rao]

Hello,

Wanted to understand the sqlite database lock a little better. Especially
while using perl DBI-sqlite module.

I did some tests and wanted to know if this is a known way of sqlite's
working.

I have a perl script that add numbers 1-1000 into a db.

Here is the code:
=
use DBI;

my $number;

for ($number=0;$number = 1000;$number++)
 {
my $dbh = DBI-connect(dbi:SQLite:dbname=/opt/test.db,,,
  {RaiseError = 1, AutoCommit = 0});

   $dbh - do(INSERT INTO test1 VALUES('$number'));

   $dbh - commit();
   $dbh-disconnect();
 };


Tests:

Test 1. When two instances of the script are run at the same time (from two
different terminals), the update gets done. Though, there is a delay in the
second instance and finishes after the first one is done.

Test 2. Run one instance of the script and try to add to the db from the
sqlite3 command line (at the same time), I get database locked message.

Test 3. Run one instance of the script and simultaneously do a select *
test1 from the command line, it does not show all the rows in the database.

I plan to use Apache+Perl+Sqlite to build a website that has about 100 users
updating the db through the browser.

I am using Sqlite 3.6.16 on RHEL.

Question 1: Do i need to worry about retry mechanism for sqlite_busy or
database locked scenarios. I do not intend to use the sqlite3 command line
for making updates.

Question 2: Is there a way to check if the database is busy or locked while
using Perl DBI?

Any pointers and sample code will help me immensely.

Thanks in advance.

Regards,
Akash
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