gistfile1.txt

mysql> explain SELECT `mentions_client_549`.* FROM `mentions_client_549` INNER JOIN `mention_details` ON ((`mention_details`.`mention_id` = `mentions_client_549`.`id`) AND (`mention_details`.`client_id` = 549)) WHERE ((`created_at` >= '2013-01-24 20:00:00') AND (`url` LIKE BINARY '%vk.com%' ESCAPE '\\')) ORDER BY `created_at` DESC LIMIT 10 OFFSET 0\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: mention_details
         type: ref
possible_keys: client_id,mention_details_client_id_label_id_index
          key: mention_details_client_id_label_id_index
      key_len: 4
          ref: const
         rows: 1427040
        Extra: Using temporary; Using filesort
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: mentions_client_549
         type: eq_ref
possible_keys: PRIMARY,ix_mentions_client_3_created_at
          key: PRIMARY
      key_len: 4
          ref: brandspotter.mention_details.mention_id
         rows: 1
        Extra: Using where

-- 5 минут спустя

mysql> explain SELECT `mentions_client_549`.* FROM `mentions_client_549` INNER JOIN `mention_details` ON ((`mention_details`.`mention_id` = `mentions_client_549`.`id`) AND (`mention_details`.`client_id` = 549)) WHERE ((`created_at` >= '2013-01-24 20:00:00') AND (`url` LIKE BINARY '%vk.com%' ESCAPE '\\')) ORDER BY `created_at` DESC LIMIT 10 OFFSET 0\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: mentions_client_549
         type: range
possible_keys: PRIMARY,ix_mentions_client_3_created_at
          key: ix_mentions_client_3_created_at
      key_len: 8
          ref: NULL
         rows: 3252522
        Extra: Using where
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: mention_details
         type: ref
possible_keys: client_id,mention_details_client_id_label_id_index
          key: client_id
      key_len: 8
          ref: const,brandspotter.mentions_client_549.id
         rows: 1
        Extra: Using index