Why a Write Op on a traditional LDAP server is expensive?

I was doing some reading up on Sun Directory Server Enterprise Edition 7 (Sun DSEE) and came across a section on using a Directory Proxy Server to distribute loads, especially Writes.

The documentation went further by explaining why a Write Operation is resource intensive. I find it refreshing to revisit technical details.

Write operations are resource intensive. When a client requests a write operation, the follow sequence of events occurs on the database: 

•  The backend database is locked

•  The entry is locked in the database cache

•  The access control check plug-in is called

•  Any backend pre-operation plug-ins are called

•  The database transaction begins

•  The database files are updated

•  The old entry cache is replaced with new data

•  The database transaction is committed

•  Any backend post-operation plug-ins are called

•  The backend database is unlocked

Because of this complex procedure, an increased number of writes can have a dramatic impact on performance.

.