Abstract: Provided are techniques for rejecting rows while locating a target row. For a row that is stored in a hash space, a row filter value is generated for that row, and the row filter value is stored with the row. While trying to locate the target row in a collision chain in the hash space, a row filter value is calculated for the target row. For the row in the collision chain, the stored row filter value of the row in the collision chain is compared with the computed row filter value of the target row. In response to determining that the stored row filter value does not match the computed row filter value, it is determined that the row in the collision chain is not the target row.

Abstract: Techniques are described for identifying conflicts between a prospective temporal key and an index of temporal keys, the index sorted based on a time value associated with each of the temporal keys. Embodiments determine whether a first temporal key within the index of temporal keys conflicts with the prospective temporal key. Here, the keys within the index may be sorted based upon a respective time value associated with each of the keys. Upon determining that the first temporal key conflicts with the prospective temporal key, the prospective temporal key is designated as conflicting with at least one existing temporal key in the index of temporal keys.

Abstract: Techniques are described for identifying conflicts between a prospective temporal key and an index of temporal keys, the index sorted based on a time value associated with each of the temporal keys. Embodiments determine whether a first temporal key within the index of temporal keys conflicts with the prospective temporal key. Here, the keys within the index may be sorted based upon a respective time value associated with each of the keys. Upon determining that the first temporal key conflicts with the prospective temporal key, the prospective temporal key is designated as conflicting with at least one existing temporal key in the index of temporal keys.

Abstract: Embodiments provide an approach for efficiently searching a temporal key index as well as enforcing key distinctiveness property in a database table corresponding to the index. For example, by addressing time range overlaps in an index having a sort order for temporal keys, a database management tool of a server system may efficiently process client requests while enforcing a temporal key property in the database table.

Abstract: Provided are techniques for rejecting rows while locating a target row. For a row that is stored in a hash space, a row filter value is generated for that row, and the row filter value is stored with the row. While trying to locate the target row in a collision chain in the hash space, a row filter value is calculated for the target row. For the row in the collision chain, the stored row filter value of the row in the collision chain is compared with the computed row filter value of the target row. In response to determining that the stored row filter value does not match the computed row filter value, it is determined that the row in the collision chain is not the target row.

Abstract: Techniques are described for identifying conflicts between a prospective temporal key and an index of temporal keys, the index sorted based on a time value associated with each of the temporal keys. Embodiments determine whether a first temporal key within the index of temporal keys conflicts with the prospective temporal key. Here, the keys within the index may be sorted based upon a respective time value associated with each of the keys. Upon determining that the first temporal key conflicts with the prospective temporal key, the prospective temporal key is designated as conflicting with at least one existing temporal key in the index of temporal keys.

Abstract: Methods and apparatus, including computer program products, implementing and using techniques for performing an index scan in a database system. A sequence of pages visited during an index scan are dynamically tracked. The tracking includes tracking the number of page accesses requiring a wait for input or output. It is determined whether prefetching of an object is desirable. The determination being made at least in part based on the number of page accesses requiring a wait for input or output. If prefetching is desirable, a prefetching method is selected among a set of available prefetching methods. An effectiveness of the selected prefetching method is continuously monitored by tracking the sequence of pages accessed and available access methods. A different prefetching method is selected from the set of available prefetching methods if the different prefetching method has a better effectiveness for a portion of the index that is being scanned.

Abstract: A row property provides a mechanism for implementing advanced functional behavior in a relational database management system (RDBMS) without introducing new data types. A row property is part of a table definition, such that, when a table is defined in the RDBMS, at least one row property is specified for one or more associated columns of rows of the table, wherein the row property has an associated functional behavior that is predefined within the RDBMS. The columns associated with the row property are generally of existing data types supported by an RDBMS. A row property may be invoked when the RDBMS processes a language statement that references the row property. When the row property is invoked, the RDBMS executes programming logic associated with the row property, in order to perform the advanced functional behavior using data stored in the associated columns.

Abstract: Techniques are described for processing a query to produce query results, the query specifying at least a first timestamp value. Embodiments receive the query for processing and access a database index containing a plurality of database keys. The database index contains one or more database index keys, each of which includes at least a timestamp value and a time zone value. Embodiments compare the first timestamp value specified in the query with a portion of one the database index keys to locate at least a portion of the query results. More specifically, the compared portion of the database index key excludes the time zone value. The located portion of the query results is then retrieved.

Abstract: Database elements are inserted into a database object by processing each of a plurality of operations in a sequential order within a first processing round to insert the database elements into the database objects, where processing for at least one operation in the order becomes suspended due to a resource request, and where at least one successive operation is initiated in response to suspension of one or more prior operations to enable prefetching of information for processing the operations. Each suspended operation is re-processed with the prefetched information in one or more additional processing rounds until processing of the operations is completed.

Abstract: Database elements are inserted into a database object by processing each of a plurality of operations in a sequential order within a first processing round to insert the database elements into the database objects, where processing for at least one operation in the order becomes suspended due to a resource request, and where at least one successive operation is initiated in response to suspension of one or more prior operations to enable prefetching of information for processing the operations. Each suspended operation is re-processed with the prefetched information in one or more additional processing rounds until processing of the operations is completed.

Abstract: A row property provides a mechanism for implementing advanced functional behavior in a relational database management system (RDBMS) without introducing new data types. A row property is part of a table definition, such that, when a table is defined in the RDBMS, at least one row property is specified for one or more associated columns of rows of the table, wherein the row property has an associated functional behavior that is predefined within the RDBMS. The columns associated with the row property are generally of existing data types supported by an RDBMS. A row property may be invoked when the RDBMS processes a language statement that references the row property. When the row property is invoked, the RDBMS executes programming logic associated with the row property, in order to perform the advanced functional behavior using data stored in the associated columns.

Abstract: Disclosed is an evaluation technique for text search with black-box scoring functions, where it is unnecessary for the evaluation engine to maintain details of the scoring function. Included is a description of a system for dealing with blackbox searching, proofs of correctness, as well experimental evidence showing that the performance of the technique is comparable in efficiency to those techniques used in custom-built engines.

Abstract: A system for controlling concurrency of access to data in a database system is provided. The system includes receiving a lock request for access to data in the database system, in which the lock request is a request for a page lock or a row lock for a corresponding row or page in the database system containing the data. The method further includes identifying a partition in the database system that contains the row or the page in the database system containing the data; associating the lock request with a partition lock on the partition that contains the row or the page in the database system containing the data; and accessing the data using the partition lock.

Abstract: A method for estimating the first access time of a plurality of currently active transactions accessing at least one database object are disclosed. In one aspect, the method may include providing a storage area of a particular size to store data for a plurality of groups corresponding to the at least one database object. Each of the plurality of groups corresponds to a particular time interval. The method includes placing each of the currently active transactions in a group of the plurality of groups based upon a time of a first access of the at least one database object by each of the currently active transactions and the particular time interval. The method also includes storing a group first access time for the group. The group first access time corresponds to the earliest first access time for any of the currently active transactions in the group. The method may also include defining the object's first, or earliest access time, to be the earliest group first access time for currently active groups.

Abstract: A system for controlling concurrency of access to data in a database system is provided. The system includes receiving a lock request for access to data in the database system, in which the lock request is a request for a page lock or a row lock for a corresponding row or page in the database system containing the data. The method further includes identifying a partition in the database system that contains the row or the page in the database system containing the data; associating the lock request with a partition lock on the partition that contains the row or the page in the database system containing the data; and accessing the data using the partition lock.

Abstract: A system and a computer readable medium for estimating the first access time of a plurality of currently active transactions accessing at least one database object is disclosed. According to varying embodiments of the system and computer readable medium disclosed herein, the present invention may provide an efficient mechanism for tracking the earliest first access time of the set of all currently active transactions accessing an object in a database system.

Abstract: An apparatus, system, and method are disclosed for updating database indexes on complex data types. Instead of deleting all the index keys for an old indexable entity, only the old index keys which are not in the set of new index keys associated with a replacement indexable entity will be deleted. In addition, only new index keys which are not in the set of old index keys are inserted into the index. In this manner, performance is greatly improved by elimination unnecessary deletions and insertions to an index.

Abstract: A method and system for controlling concurrency of access to data in a database system, includes: partitioning a table in the database system into a plurality of partitions; receiving a request for access to data; determining a partition of the plurality of partitions that contains the data; determining if the data has been committed; and if so, avoiding locking the partition in response to the request. By avoiding locking the partition when the data has been committed, the number of partition locks that need to be requested from a local resource lock manager is reduced, improving performance.

Abstract: A system, method and computer readable medium containing programming structions for an improved latch mechanism for use in a programming environment running concurrent tasks is disclosed. According to one aspect of the present invention, a latch is provided to a first task which is requesting access to a resource. After such access, the first task holds the latch, which is also released from the first task. The first task holding the latch marks the latch stealable, and if the latch is not marked stolen by another task, the first task can mark the latch unstealable. In another embodiment of the present invention, if the first task is provided a latch marked stealable, the resource associated with the stealable latch will be placed in a consistent state before the first task accesses the resource.