[SQL] predicate locking

2005-06-12 Thread Daniel Roth
Hi Tom Lane and the postgres help state, "AFAIK, no commercial database does predicate locking either" (12.2.2.1. Serializable Isolation versus True Serializability) But MSSQL (SQL Server) does predicate locking. From MSDN "SERIALIZABLE Places a range lock on the data set, preventing other use

Re: [SQL] predicate locking

2005-06-12 Thread Tom Lane
Daniel Roth <[EMAIL PROTECTED]> writes: > But MSSQL (SQL Server) does predicate locking. > Places a range lock on the data set, preventing other users from > updating or inserting rows into the data set until the transaction is > complete. This is the most restrictive of the four isolation levels.

Re: [SQL] predicate locking

2005-06-12 Thread Daniel Roth
Hi Tom Apologies for my previous double post. In "12.2.2.1. Serializable Isolation versus True Serializability" It sates: "To guarantee true mathematical serializability, it is necessary for a database system to enforce predicate locking, which means that a transaction cannot insert or modify a

Re: [SQL] predicate locking

2005-06-12 Thread Tom Lane
Daniel Roth <[EMAIL PROTECTED]> writes: > It sates: "To guarantee true mathematical serializability, it is > necessary for a database system to enforce predicate locking, which > means that a transaction cannot insert or modify a row that would have > matched the WHERE condition of a query in anoth