To upgrade from 1.3 to 1.3.1, run the upgrade.php script.
Note that on a large database, this can take a very long time (up to several hours). 
For example with 1,000,000 rows in the link_keyword table,
it takes around 30 minutes. BACK UP YOUR DATABASE BEFORE DOING THE UPGRADE.
Delete the upgrade.php file after upgrading.


To upgrade from 1.2.5 to 1.2.6, run the upgrade_to_1.2.6.sql
script in sql directory on the sphider database.


To upgrade from 1.2.3 to 1.2.5, run the upgrade_to_1.2.5.sql
script in sql directory on the sphider database.


To upgrade from 1.1.0 to 1.2, run the upgrade_to_1.2.sql 
script in sql directory on the sphider database.