[EMAIL PROTECTED] wrote: > is there anyone who can explain to me the difference between > a shared and an exclusive lock on SAP DB objects?
share locks are those locks set (dependant on the isolation level used) during reading rows/tables. they do NOT collide with other share locks on the same SAP DB object. exclusive locks are set (no matter which isolation level is used) during insert/update/delete of rows. They collide which each other lock (no two users are allowed to change a row at the same time, i.e. the second has to wait for a commit/rollback of the first one). A user is not allowed to change a row which was share-locked by another user. The other user told the database that he wanted to see the unchanged row (therefore set the share lock explicitely/implicitely) during his transaction, therefore the new user has to wait for the end of this transaction. Usually (default-isolation level) a user will NOT see rows with exclusive lock. Only with isolation level 0 he will see (not collide, because he does not want to set a lock by its own) those exclusive-locked rows. For a description of the different isolation level, please see the reference manual --> transactions Elke SAP Labs Berlin _______________________________________________ sapdb.general mailing list [EMAIL PROTECTED] http://listserv.sap.com/mailman/listinfo/sapdb.general
