MySQL – How to Get Estimate Cost of Executing a Query

I recommend using Percona Server, for the slow query log enhancements. I answered a similar thread to this on Stack Overflow:

https://stackoverflow.com/questions/3393206/what-is-the-equivalent-query-in-mysql/3443944#3443944

Take a look at this in particular (from http://www.percona.com/docs/wiki/percona-server:features:slow_extended?redirect=1#changes_to_the_log_format):

# User@Host: mailboxer[mailboxer] @  [192.168.10.165]
# Thread_id: 11167745  Schema: board
# QC_Hit: No  Full_scan: No  Full_join: No  Tmp_table: Yes  Disk_tmp_table: No
# Filesort: Yes  Disk_filesort: No  Merge_passes: 0
# Query_time: 0.000659  Lock_time: 0.000070  Rows_sent: 0  Rows_examined: 30  Rows_affected: 0  Rows_read: 30
#   InnoDB_IO_r_ops: 1  InnoDB_IO_r_bytes: 16384  InnoDB_IO_r_wait: 0.028487
#   InnoDB_rec_lock_wait: 0.000000  InnoDB_queue_wait: 0.000000
#   InnoDB_pages_distinct: 5
select count(distinct author_id) from art87.article87 force index (forum_id) where forum_id = 240215 and thread_id = '710575' 

I don't know of a way to do this in the plan from Management Studio, but this is one of the many things the free SentryOne Plan Explorer will do for you when you generate an actual plan from within the tool - it includes all the runtime metrics per statement.