Not sure how you stop or restrict how the Database grows, but the size of the database will vary and depends on the number of hosts & VMs managed, frequency of performance data collection and type of database.
Each stat sample collected is about 60 bytes for SQL, 100 bytes for Oracle, and each event stored is 1600 bytes for SQL, 600 bytes for Oracle.
Using default settings, the statistical data for 25 hosts running 8-16 VMs per host will plateau around 40-60 MB in a year (80-140 MB if set to "full").
Each month, the average number of events generated will also consume about 190 MB in SQL, and 70 MB in Oracle. Total DB size after a year is expected to be around 2.20 Gb in SQL, and 1.0 Gb in Oracle.
Using default settings, the statistical data for 75 hosts running 8-16 VMs per host will plateau around 90-150 MB in a year (200-330 MB if set to "full"). Each month, the average number of events generated will also consume about 190 MB in SQL, and 70 MB in Oracle.
Total DB size after a year is expected to be around 2.40 Gb in
SQL, and 1.2 Gb in Oracle.
http://www.vmware.com/pdf/vc_technical_best.pdf