[Serusers] scope & database operations for avp_write

Valued Colleagues, Can anyone tell me what is the scope of avp_write?! Is it global / per-transaction / per-message?! I would like to have something similar to it with global scope so that I can set the string "callfwd" once by executing: avp_write("sip:211@10.1.10.22:5060", "s:callfwd"); and then keep using it for each SIP message processing using: avp_pushto("$ruri", "s:callfwd"); Also, do the avp_write and avp_pushto involve Database access operations?! i.e. Does avp_write store the string in database and avp_pushto looks it up form the database or is the information stored in memory?! I want to avoid database access to ensure improved performance. Thanks ramin