Postgresql supports automatic conversions between data types wherever it's reasonable. Transactions, Isolation and Locking Postgresql supports transactions. Both may change. No other isolation levels for transactions are supported. With AutoCommit on, a query never places a lock on a table.
Readers never block writers and writers never block readers.
Then a query induces a shared lock on a table and blocks anyone else until the transaction has been finished. The C statement can be used to apply an explicit lock on a table. To ensure that a table being selected does not change before you make an update later in the transaction, you must explicitly lock it with a C statement before executing the select. Inner joins use the traditional syntax. The max size of table and column names cannot exceed 31 charaters in length.