Abstract: A logical backup of a database is performed that allows physical properties of the database to be preserved upon restore. The physical properties of the database include properties related to storage of the data on the hard disk. Preserving the physical properties of a database allows performance debugging of the source database by performing performance tests on the target database rather than a production system. Incremental backup of metadata of a database is performed to minimize execution of statements that provide the final configuration of the database. Incremental backup is performed by restoring a database using a full backup and applying incremental backups to reach a particular state. The user can inspect the restored database after applying each incremental backup to determine whether the database has reached a desired state.

Abstract: A database system performs hash join process for processing queries that join an inner and an outer database table. The hash join processes builds a hash table in memory for the inner table. The database system receives a limit on the memory for storing the hash table. The database system maximizes the number of partitions stored in memory for the hash table. If the hash table exceeds the limit of the memory while adding rows from the inner table, the database system selects a partition for spilling to a persistent storage. The partition selected for spilling to may be the largest partition or a partition larger than most of the partitions. The database system initializes the hash table to a number of partitions that is substantially equal to half of the total number of blocks that can be stored within the specified limit of memory for the hash table.

Abstract: A database system performs hash join process for processing queries that join an inner and an outer database table. The hash join processes builds a hash table in memory for the inner table. The database system receives a limit on the memory for storing the hash table. The database system maximizes the number of partitions stored in memory for the hash table. If the hash table exceeds the limit of the memory while adding rows from the inner table, the database system selects a partition for spilling to a persistent storage. The partition selected for spilling to may be the largest partition or a partition larger than most of the partitions. The database system initializes the hash table to a number of partitions that is substantially equal to half of the total number of blocks that can be stored within the specified limit of memory for the hash table.