International Business Machines Corporation

Michael Jeffrey Winer

Matthew Albert Huras

Catherine Suzanne McArthur

Bishwaranjan Bhattacharjee

Timothy Ray Malkemus

Dale Murray McInnis

Bruce Gilbert Lindsay

Roger L Q Zheng

Miroslaw Adam Flasza

Leslie Anne Cranston

Nelson Hop Hing

Roger Luo Q Zheng

Mir Hamid Pirahesh

Sriram Kolinjivadi Padmanabhan

Robert William Lyle

Aamer U Sachedina

Keriley Kay Romanufa

Effi Ofer

Jeffrey James Goss

Leslie Anne Buback

Matthew J Spilchen

Robert T Berks

Lorysa M Meadowcroft

Guy Maring Lohman

Richard Sefton Sidle

Calisto Paul Zuzarte

Namik Hrle

Sam Sampson Lightstone

Gopi K Attaluri

Peter Haas

David Everett Simmen

Roberta Jo Cochrane

Oliver Draese

Torsten Steinbach

Tuong Chanh Truong

David C Sharpe

Gary Valentin

David Tremaine

Leo Tat Man Lau

Markos Zaharioudakis

Petrus Kai Chung Chan

Leo T M Lau

Kathy A McKnight

Quanhua Hong

Sarah Posner

Roger Lq Zheng

Iqbal A Goralwalla

Catharina K Wong

Effi Ofar

Ashutosh Vir Vikram Singh

Shaun K Thornborough

According to a present invention embodiment, a system conducts a scan on a database object index with one or more gaps. The system generates one or more combinations of values for the gaps within an index with respect to an operation. Each combination of values is generated by scanning the index based on a combination of one or more scan values, adjusting a value for a gap based on scan results, and adjusting the scan values for a succeeding scan based on the scan results to reduce a quantity of scans. The index includes at least two database object elements. One or more scans of the index utilizing the combinations of values are conducted to retrieve data from the database and accommodate each gap in the index. Present invention embodiments further include a method and computer program product for conducting the index scan.

Accommodating gaps in database index scans

A computer implemented method, apparatus, and computer usable program code for deleting rows in a multidimensionally clustering database. A multidimensional clustering processor receives a request to delete a set of multidimensionally clustering data. The multidimensional clustering processor determines whether all multidimensionally clustering data is located in a block. Responsive to all multidimensionally clustered data qualifying for deletion, the multidimensional clustering processor deletes all data in the block to delete the set of multidimensionally clustered data.

Method for fast deletion of physically clustered data

Implementation of append mode concurrent insert operations in tables in a page-based concurrent relational database management system is carried out by defining a set of last pages as a current cache into which rows may be inserted by appenders. Append mode insert operations for each page in the current cache are serialized. Appenders seek to access the pages in the current cache using a two-pass process in which latches are sought to be acquired conditionally in the first pass and unconditionally in the second pass. A shared data structure is provided to define a current cache and a next cache for a table supporting append mode inserts in the relational database. The shared data structure includes information reflecting the unused space for each page in the current cache.

Computer program and product for append mode insertion of rows into tables in database management systems

The present solution addresses the need to carry out reorganization of a database storage. A statistics-based reorganization check procedure is performed on at least first database tables and indexes, resulting in a preliminary reorganization recommendation. Information on workload on tables and indexes of said database storage is received. Based on the information on workload and the preliminary reorganization recommendation, it is decided whether to carry out reorganization of the database storage in accordance with the preliminary reorganization recommendation.

Workload aware checking of database reorganization

An information retrieval system and method are provided for minimizing the number of blocks searched in a cell before recording a new record in the table and determining which block can be assigned if a table has space available to store a new record in the case an additional block should be associated with a cell. Dimensions for a table are identified, and at least one block in the table is associated with a dimension value for each dimension, where each block comprises contiguous storage pages. The block can be further associated with a cell; this associated cell has a unique combination of dimension values comprising an dimension value for each of the dimensions. A unique associated bit list for each dimension value for each dimension has a unique corresponding list entry for each block associated with that dimension value, and a unique associated bit list for each cell has a unique corresponding list entry for each block associated with that cell.

System and method for space management of multidimensionally clustered tables

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.

Method for estimating a first access time of transactions accessing a database object

A computer implemented method, apparatus, and computer usable program code for deleting rows in a multidimensional clustering database. A multidimensional clustering processor receives a request to delete a set of multidimensionally clustered data. The multidimensional clustering processor determines whether all multidimensionally clustered data is located in a block. Responsive to all multidimensionally clustered data qualifying for deletion, the multidimensional clustering processor deletes all data in the block to delete the set of multidimensionally clustered data.

Method and apparatus for fast deletion of physically clustered data

Method for append mode insertion of rows into tables in database management systems

The invention herein provides method and apparatus for managing attribute-tagged index entries contained in an index by assigning or tagging an index entry attribute indicator to a newly inserted index entry (that is, at the time when a key data value is inserted into the index, the key data value becomes a newly inserted index entry and an attribute indicator is tagged to the newly inserted index entry). The index entry can be placed anywhere within the index. Once a group of attribute-tagged index entries have been inserted into the index, the attribute identifiers can be switched off instantaneously (that is, the attribute associated with the attribute indicators is disabled).

Managing attributed-tagged index entries

A multi-level locking hierarchy for a relational database includes a locking level applied to a multi-dimensionally clustering table, a locking level applied to blocks within the table, and a locking level applied to rows within the blocks. The hierarchy leverages the multi-dimensional clustering of the table data for efficiency and to reduce lock overhead. Data is normally locked in order of coarser to finer granularity to limit deadlock. When data of finer granularity is locked, data of coarser granularity containing the finer granularity data is also locked. Block lock durations may be employed to ensure that a block remains locked if any contained row remains locked. Block level lock attributes may facilitate detection of at least one of a concurrent scan and a row deletion within a block. Detection of the emptying of a block during a scan of the block may bar scan completion in that block.

System and method for a multi-level locking hierarchy in a database with multi-dimensional clustering

A memory buffer facilitates log catchup for online operations. Certain designated areas of memory are allocated for one or more buffers for use during online operations (e.g., reorganization, create index, etc.). Concurrent update activities to the target object write informational records into the one or more buffers. If the buffers become full, the informational records may be written to logs for persistent storage. After online operations finish building all or a suitable portion of the shadow object, log catchup is performed by first applying activities in the informational records from the buffer and thereafter applying activities from logs, if necessary. The invention helps solve the drawbacks of log catchup since the buffer contains only the information related to the target shadow object. Also it does not involve physical I/Os, as these records are all in memory.

System and method for using a buffer to facilitate log catchup for online operations

A technique for recovering a dropped table is provided. One or more table spaces are specified prior to one or more tables being dropped from the specified one or more table spaces. When a table is to be dropped from the one or more specified table spaces, a table identifier, a time stamp, and table definition attributes are stored for the dropped table in a data structure and the table is dropped. Upon receiving a request to restore a table space from the one or more specified table spaces, each of the one or more tables in the table space being restored is recovered using the data structure.

Method, system, computer product for recovering dropped database table specifying one or more table spaces, recovering the table space being restored using the dropped table history data structure

A method and system for suspending log-based updates to a database in a manner that permits resumption of log-based updating without reinitializing the database. The method and system thereby permit efficient alternation between a log-based update mode and a database access mode. Unplayed log records are protected as revisions of database pages at the time that the log-based update was suspended. This approach permits log-based updating to resume at the same point at which log-based updating was suspended. In order to ensure consistent data for access while in database access mode, a roll-back procedure creates consistent data pages that are used for access and discarded when log-based update resumes.

Method and apparatus for interrupting updates to a database to provide read-only access

A callback to a data manager is carried out from an index manager in a query processing system for an index-data fetch to enable an index page held stabilized by an index manager to remain stabilized during predicate checking or data consumption operations. The index manager locates a data identifier in an index and calls back to a data manager to access the data indicated by the data identifier. The data manager may carry out a predicate check or a data consuming operation on the data and if this is the case the index manager may access the next data identifier in the index when the data manager callback is complete. The index page need not be destabilized in such a case.

Efficient index-data fetch via callback for table data

The use of a centralized version table allows for efficient object switching. Rather than synchronizing all database agents to recognize a newly created file as containing the most recent version of a given object, database agents requiring access to the given object need only consult the centralized version table to learn file identity information. That is, the database agents consult the centralized version table to determine which of the files associated with a given object contain the most recent version of the given object. Mechanisms associated with the use of the centralized version table also provide for efficient recovery from a failure that has occurred during an object switching transaction.

System and method for decoupling object identification for the purpose of object switching in database systems

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Markham, Canada

Michael Jeffrey Winer