Drupal Database size was very huge in production. As we are using memcache, apc and varnish for cache, Database should not be more. But cache_form we are using drupal database.  So we want to find the size of each tables in the database.

First we wrote a query to find Database size

SELECT table_schema "DB Name", Round(Sum(data_length + index_length) / 1024 / 1024, 1) "DB Size in MB" FROM   information_schema.tables GROUP  BY table_schema;

From the above query, we able to get the each database size. it shows 1038mb as our database size.

Next we wrote one more query to find the each table size in our database

SELECT table_name AS "Tables", round(((data_length + index_length) / 1024 / 1024), 2) "Size in MB" FROM information_schema.TABLES WHERE table_schema = "db_name" ORDER BY (data_length + index_length) DESC;

result shows, cache_form table alone occupies 750 mb, others are 10mb or below. So this confirms that, we need to work on how to reduce the cache_form table size.

There was more resources was available in the internet to resolve this issue, some of them are

https://github.com/saitanay/force_fct

http://drupal.stackexchange.com/questions/11321/how-to-keep-cache-form-small

http://drupal.stackexchange.com/questions/69803/cache-form-table-size-is-enormous

http://drupal.stackexchange.com/questions/96744/cache-form-drupal-change-expire-time

we adapted solution which clears the cache_form table in corn

DELETE FROM {cache_form} WHERE expire < now();