International Business Machines Corporation

Michael Joshua Snowbell

Paul Miller Bird

Calisto Paul Zuzarte

Adam J Storm

Sam Sampson Lightstone

Christian Marcelo Garcia-Arellano

John Frederick Hornibrook

Qi Cheng

Yuk Kuen Chan

Hebert Walter Pereyra

Ivan Popivanov

Xiaoyan Qian

Matthew James Carroll

Catharina K Wong

Wing Yan Lau

Michael Arthur Franciscus Stuy

Yeung-Kuen See

Jesse Lee

Yuk-kuen Chan

A system and method are provided for updating database statistics for use in generating query execution plans. A first query for a database is received, for example by a compiler, and the compiler accesses statistics associated with the first query for optimizing a query execution plan for the first query. The statistics may be accessed from a first cache. If the statistics retrieved from the first cache are determined to be stale, the system obtains updated statistics and may store them in a temporary cache. The stale statistics in the first cache are marked as invalid. Existing queries using the first cache may continue to use the first cache, while new queries may be provided with updated statistics.

Optimized collection of just-in-time statistics for database query optimization

Providing cost model data for tuning query cache memory size in database systems. In one aspect, a query is received, and a query cache is checked for a stored query matching the received query. In response to a cache miss occurring, a token representing the received query is generated and checked for matching a token stored in a simulation area, each stored token representing a query object previously evicted from the query cache. A processing time saved by an avoidance of the cache miss is determined, and a cache size needed to avoid the cache miss is determined only when the generated token matches a stored token, by summing sizes of all query objects represented by the stored tokens. Each stored token is included in a stub that also includes the size of the represented query object and an identification number indicating a stored order.

Providing cost model data for tuning of query cache memory in databases

In a database system that supports object name overloading, database query statements are compiled and cached as data structures so that object level privileges are correctly resolved. Database query statements stored in the cached data structures are utilized when appropriate and a new compilation is performed when an incorrect resolution would result. The data structures are stored in a predefined order to ensure that a deterministic search of the cache is efficiently performed.

System and method for caching database query statements

A multi-node relational database management system is provided that can be embodied in software for managing a database having declared temporary tables associated with respective software application programs. The system comprises a plurality of nodes. The nodes include a catalog node for maintaining a list of identifiers for declared temporary tables associated with any application; a coordinator node for an application; at least one subordinate node for the application, the subordinate node having at least one partition of the declared temporary tables of the application; and a declared temporary table manager for causing the coordinator node to maintain for the application a list of declared temporary tables.

Method and apparatus for synchronizing not-logged application temporary tables in a multi-node relational database management system

A relational database management system which determines the shareable status of an executable object (section) in an cache. The shareable status is defined for a section in a cache by the system maintaining an identification list which has reference to database entities which are affected by a statement in the current unit of work. When a statement is compiled, the compiler generates a list of dependencies, which list is compared with the identification list. If the statement data dependencies are on the identification list, the statement will be treated as non-shareable until the completion of the current unit of work.

Accommodation of data definition statements in the sharing of dynamic SQL statements

The invention provides a data processing system, a method, computer program product and software for operating it where the data processing system includes a number of interconnected nodes. At least one data partition resides on one of the nodes, and one or more tables reside in a data partition. One of the nodes has a catalogue containing metadata describing tables and other objects and relationships therebetween in the data processing system. There is a global instruction cache at each node having a statement portion storing instruction statements and associated executables; each of the executable is designed for a particular environment; the instruction cache includes a dependency portion which lists objects and links them to the corresponding executable entries that depend on the objects; the instruction cache includes a shipped variation portion, each entry of the shipped variation portion refers to one executable entry and identifies the node from which the statement associated with the executable was originally shipped and the identification of such executable in the node from which it was originally shipped. The cache includes an invalidations in progress portion, each entry of the invalidations in progress portion refers to an object entry in the dependency portion.

Method and apparatus for cross-node sharing of cached dynamic SQL in a multiple relational database management system environment

A method and system for caching dynamic SQL statements and their sections at different nodes in a multiple node Relational Database Management System (RDBMS) while maintaining cache and application integrity across all nodes. Each node in the RDBMS having a global cache shared by all applications on that node. One of the nodes in the RDBMS being a catalogue node which controls access to a database. The catalogue node maintaining a list of participating nodes that have requested access to the database controlled by the catalogue node. The list of participating nodes being used to notify each participating node of any changes to the database that may affect the validity of a dynamic SQL statement stored in the global cache of the node.

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Thornhill, Canada

Michael Joshua Snowbell