International Business Machines Corporation

Kostas Rakopoulos

Martin Oberhofer

Jens Peter Seifert

Stephen Rees

Daniele Costante Zilio

Darren Andrew Pepper

Xi Sun

Muhammad Esaad Afaque

Methods, computer program products, and systems are presented. The method computer program products, and systems can include, for instance: obtaining a query statement; parsing the query statement and determining from the parsing that the query statement is a compound predicate query statement that includes a first predicate and a second predicate; responsively to the parsing, rewriting the obtained query statement to provide a transformed query statement, wherein the rewriting includes (a) specifying generating of a temporary table, wherein the specified generating uses data values of the first predicate and (b) specifying a join function that uses the temporary table and a table referenced in the query statement; evaluating a candidate access path associated to the transformed query statement; selecting the candidate access path as an access path for execution; and executing the transformed query statement according to the selected candidate access path for execution.

Compound predicate query statement transformation

A logging process in a data storage system having a set of storage tiers, each storage tier of the set of storage tiers having different performance characteristics, wherein the set of storage tiers is divided into a plurality of subsets of storage tiers using the performance characteristics, may include initiating the logging process for creating a separate log file for each of the plurality of subsets of storage tiers for maintaining a history of data changes in the subset of storage tiers, thereby creating a plurality of log files. In response to a change in data stored in at least one storage tier of a subset of storage tiers of the plurality of subsets of storage tiers, one or more log records including information about the change may be generated and written into respective log files.

Logging process in a data storage system

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Toronto, Canada

Kostas Rakopoulos