I've finally accepted that creating a new address for each
transaction is kind of a good idea..
 
 Am I correct in thinking - that for each customer that comes to my shop
I generate/give to them a unique bitcoin address , so that I know that
if the address in question receives money , then it's surely from the
person I gave the address to..

 This is fine, - but that could end being hundreds or even thousands of
addresses being generated everyday..

 I understand that generating a new address is not a big deal, but the
housekeeping of my bitcoin server becomes an issue..

 How can I delete addresses from the database when I am done with them
( for example, once an address receives coins, I make a note of it in my
mysql for example, and 'move' the coins to one central internal bitcoin address).

If I have thousands of addresses/accounts , anytime I do a listaccounts or
getbalance I'm going to get a really long list..

 So , that's my query - can I delete bitcoin addresses and/or accounts from
bitcoind to keep everything running smooth..