Abstract: Methods, computer programs and system for executing a query on data that has been partitioned into a plurality of partitions are provided. The method includes providing partitioned data including one or more columns and the plurality of partitions. The partitioned data includes a limit key value associated with each column for a given partition. The method further includes receiving a query including a predicate on one of the one or more columns of the partitioned data; and utilizing the predicate on the one of the one or more columns in a pruning decision on at least one of the one or more partitions based on the limit key values associated with the plurality of partitions.

Abstract: Provided are a techniques for processing a query including semi-joins. At execution time, a next semi-join is selected from the semi-joins for execution in a current round of semi-join executions. A reporting threshold is determined that indicates a number of record-identifiers to be retrieved for the determined semi-join. The selected semi-join is executed until the determined number of record identifiers are retrieved.

Abstract: Processing non-Boolean term conditions in database queries. A query that is a request for data in a database is received and includes at least one uneven non-Boolean term condition that spans multiple tables in the database. The non-Boolean term condition is split into separate portions, each of the portions providing a Boolean term that can be satisfied by accessing one table in the database. The separate portions are executed independently to find at least one data result in the database that satisfies the Boolean term of each separate portion, and the data result from each separate portion are combined into a final result that satisfies the query.

Abstract: A multi-table query system utilizes indexes to provide filtering and then obtains the desired data. The multi-table query system reduces excessive data retrieval by minimizing access by multi-table joins to data pages until absolutely necessary in a process of executing the query. The multi-table query system improves runtime performance and minimizes a risk of poor performance if the optimizer of the DBMS incorrectly estimates the filtering and chooses a less than optimal table join sequence. The multi-table query system does not require the implementation of any additional indexing technology for the DBMS. Existing indexing technologies, such as the standard single table B-tree index design can exploit the multi-table query system.

Abstract: An improved method for processing a multiple table query includes: determining if any tables in the query require materialization; for each table in the query that requires materialization, deriving at least one join predicate on a join column; determining if any tables earlier in a join sequence for the query has same join predicates; and applying the at least one derived join predicate to an earlier table in the join sequence, if there is at least one table earlier in the join sequence that has the same join predicate. This significantly reduces the number of rows that are joined before arriving at the final result.