Abstract: A system and/or method are implemented to process queries to a database. In particular, the processing of queries to the database is enhanced by enhancing the determination of join orders of tables implicated in queries. Join orders between relatively large numbers of tables are determined by dividing the set of tables to be ordered into a plurality of subsets of tables, and ordering the individual subsets of tables.

Abstract: A database system optimizes database queries that comprise subqueries. The database system factors out computation from two or more subqueries to a reusable subquery. The reusable subquery returns a result set. The subqueries are rewritten to use the result set and the database query modified to use the rewritten subqueries. The modified database query performs efficiently since the result set is computed only once for each subquery that uses the reusable query. The database system also composes nested subqueries that compute aggregate values. The database system identifies an inner subquery nested within an outer subquery, each subquery computing an aggregate value. The database system determines a new aggregate function corresponding to a composition of aggregate functions of the inner and the outer queries. The database system determines a composed query using the inner query with the outer query. The composed query uses the new aggregate function.

Abstract: Backups and restore operations of database are customized by performing partial backups and restores. The database maintains information describing database objects that are backed up by subsequent backup operations. The data set that is backed up by backup operations can be modified by executing alter backup commands. An alter backup command identifies one or more database objects and specifies whether the database object should be excluded or included from backup operations. The alter backup command can specify database objects that do not exist in the database. These objects are included or excluded in accordance with the alter backup command whenever they are created in the database. The alter backup command can associate a criteria with a database object in order for the database object to be included or excluded in accordance with the alter backup command.

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 system and/or method are implemented to process queries to a database. In particular, the processing of queries to the database is enhanced by enhancing the determination of join orders of tables implicated in queries. Join orders between relatively large numbers of tables are determined by dividing the set of tables to be ordered into a plurality of subsets of tables, and ordering the individual subsets of tables.

Abstract: A system and/or method are implemented to process queries to a database. In particular, the processing of queries to the database is enhanced by enhancing the determination of join orders of tables implicated in queries. Join orders between relatively large numbers of tables are determined by dividing the set of tables to be ordered into a plurality of subsets of tables, and ordering the individual subsets of tables.

Abstract: A system and/or method are implemented to process queries to a database. In particular, the processing of queries to the database is enhanced by enhancing the determination of join orders of tables implicated in queries. Join orders between relatively large numbers of tables are determined by dividing the set of tables to be ordered into a plurality of subsets of tables, and ordering the individual subsets of tables.

Abstract: A system and method for enhancing data throughput in data warehousing environments by connecting multiple servers having local storages with designated external storage systems, such as, for example, those provided by SANS. The system and method may preserve a full reference copy of the data in a protected environment (e.g., on the external storage system) that is fully available. The system and method may enhance overall I/O potential performance and reliability for efficient and reliable system resource utilization.

Abstract: A system and/or method are implemented to process queries to a database. In particular, the processing of queries to the database is enhanced by enhancing the determination of join orders of tables implicated in queries. Join orders between relatively large numbers of tables are determined by dividing the set of tables to be ordered into a plurality of subsets of tables, and ordering the individual subsets of tables.

Abstract: A system and method for enhancing data throughput in data warehousing environments by connecting multiple servers having local storages with designated external storage systems, such as, for example, those provided by SANs. The system and method may preserve a full reference copy of the data in a protected environment (e.g., on the external storage system) that is fully available. The system and method may enhance overall I/O potential performance and reliability for efficient and reliable system resource utilization.

Abstract: A system and/or method are implemented to process queries to a database. In particular, the processing of queries to the database is enhanced by enhancing the determination of join orders of tables implicated in queries. Join orders between relatively large numbers of tables are determined by dividing the set of tables to be ordered into a plurality of subsets of tables, and ordering the individual subsets of tables.