I've noticed over the past few weeks that a Drupal installation that I help maintain has started to grow gigantic. The main culprit is the cache table - it's currently increased an ungodly 5.6GB, adding roughly 500-700MB per day! The table has just about 3,000,000 rows and doesn't seem to be shrinking at all. Given what I can gather from mysql, it appears as though things should have an expiration, but nothing does.
[root@jim]# ls -lh | grep G
total 10G
-rw-rw---- 1 mysql mysql 1.2G Aug 12 10:45 accesslog.MYD
-rw-rw---- 1 mysql mysql 5.6G Aug 12 11:10 cache.MYD
[root@jim]# mysql -u root -p
mysql> describe cache;
+------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| cid | varchar(255) | NO | PRI | | |
| data | longblob | YES | | NULL | |
| expire | int(11) | NO | MUL | 0 | |
| created | int(11) | NO | | 0 | |
| headers | text | YES | | NULL | |
| serialized | smallint(6) | NO | | 0 | |
+------------+--------------+------+-----+---------+-------+
6 rows in set (0.00 sec)
mysql> select count(*) from cache;
+----------+
| count(*) |
+----------+
| 2966905 |
+----------+
