Sharing session data to all subdomain codeigniter - codeigniter

Question

I am trying to use one session data for all of my subdomains.
I have created a subdomain in cpanel like this : *.mydomain.in
and my *.mydomain.in uses the same path as my mydomain.in example:
mydomain.in uses path on my server: /public_html/mydomain.in
*.mydomain.in uses path on my server: /public_html/mydomain.in
Now the problem is every time I visit the site it's creating a different session. For example:
I visit mydomain.in .... it creates a session.
I visit example.mydomain.in .... it creates a different session
I again visit mydomain.in ... it creates a different session.
my codeigniter config file:
$config['encryption_key'] = 'MY-SECRET-KEY-HERE';
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 0;
$config['sess_expire_on_close'] = TRUE;
$config['sess_encrypt_cookie'] = TRUE;
$config['sess_use_database'] = TRUE;
$config['sess_table_name'] = 'ci_sessions';
$config['sess_match_ip'] = TRUE;
$config['sess_match_useragent'] = TRUE;
$config['sess_time_to_update'] = 300;
$config['cookie_prefix'] = "";
$config['cookie_domain'] = ".mydomain.in";
$config['cookie_path'] = "/";
$config['cookie_secure'] = FALSE;
Any help or suggestion would be a great help. Thanks in advance.

Answer 1

Here's how I solved the issue.
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 0;
$config['sess_expire_on_close'] = TRUE;
$config['sess_encrypt_cookie'] = TRUE;
$config['sess_use_database'] = TRUE;
$config['sess_table_name'] = 'ci_sessions';
$config['sess_match_ip'] = TRUE;
$config['sess_match_useragent'] = FALSE;
$config['sess_time_to_update'] = 300000000;
$config['cookie_prefix'] = "etc_anything_";
$config['cookie_domain'] = ".mydomain.in";
$config['cookie_path'] = "/";
$config['cookie_secure'] = FALSE;

Answer 2

Mohamed Sufian's answer is largely correct, but note that as per the Session Docs, the cookie_prefix setting is ignored by the session driver. If you want to have an instance specific cookie name you will need to edit the sess_cookie_name configuration option.
For example:
$config['sess_cookie_name'] = 'my_prefix_ci_session';
$config['cookie_prefix'] = "my_prefix_"; // Only relevant for non-session cookies
$config['cookie_domain'] = ".example.com";
$config['cookie_path'] = "/";