Assigning array to another array

I'm using these URLs for matching the correct backend servers. I took this ProxyPass iRule: http://devcentral.f5.com/Wiki/default.aspx/iRules/proxypass.html and rewrote it, so the connection is forwarded directly to backend server, rather then to assigned pool. I also modified matching of the correct server - I'm using array, rather then the external datagroup file (because of performance issues)

the format of array is:

 
 key name                    item1               item2          
  external_url {internal_url internal_host_ip } 
 

I'm using two iRules, one for filling of the array (it works together with bash script, which generates the data group) and the second which acts as the reverse proxy.

When the data group is modified, i need to run an iRule, which creates array from items in the iRule. During this, the array needs to be cleared and then filled again. My concern is, that when this array is unset and before it is filled again (processing of too many items in the data group takes some time), there must be some delay in processing of new connections. But surprisingly, when performing tests, no connection ends with error, during the time, when the array is refilled.

Robert