Transaction support for indexed summary views

Materialized views have become a standard technique for performance improvement in decision support databases and for a variety of monitoring purposes. In order to avoid inconsistencies and thus unpredictable query results, materialized views and their indexes should be maintained immediately within user transaction just like indexes on ordinary tables. Unfortunately, the smaller a materialized view is, the higher the concurrency contention between queries and updates as well as among concurrent updates. Therefore, we have investigated methods that reduce contention without forcing users to sacrifice serializability and thus predictable application semantics. These methods extend escrow locking with multi-granularity (hierarchical) locking, snapshot transactions, multi-version concurrency control, key range locking, and system transactions, i.e., multiple proven database implementation techniques. The complete design eliminates all contention between pure read transactions and pure update transactions as well as contention among pure update transactions as well as contention among pure update transactions; it enables maximal concurrency of mixed read-write transactions with other transactions; it supports bulk operations such as data import and online index creation; and it provides recovery for transaction, media, and system failures.