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ORACLE COHERENCE TUTORIAL PPT CODE

For example did a specific and filter have more impact on the query performance then a like filter? Would an index on one of the fields changed the performance?Ĭoherence 3.7.1 introduced two new features to support static and dynamic evaluation of query performance. In addition it was impossible to determine which portions of the query had the most impact.

ORACLE COHERENCE TUTORIAL PPT CODE

Prior to Coherence 3.7.1 there was no way to determine the performance of a query other then timing it in code or by hand, neither of which being optimal or even convenient. Entities may or may not efficiently extract data and as a result, keeping an index up to date may not be worth the time saved in a query.These are but a few of the concerns about why you may or may not apply a index to an entity field.

However indices are not without cost, requiring memory and processing power to keep up to date and are directly dependent on their entity objects for data extraction. Indexes provide an identical function to their database cousins allowing Coherence to more quickly return data. Filter performance can then be improved by the thoughtful use of indexes. Behind the scenes QueryHelper creates a set of Filters which match the provided select statement.įilters are then executed against a cache which performs the operation on each member of the cluster, aggregates the results and returns it.

Using Queries - Queries use and SQL like syntax and the import Ĭlass to create a Filter instance.

Filters are then executed against a cache and return a result set.

Using Filters - Filters, based on the class, allow the development of queries using combinations of value extractors and combinations of and, or, not, like and similar filters to perform queries.

Queries are performed in one of two ways: The Coherence Query Language or CohQL allows developers to create complex SQL like queries against cached data.

Trace - How can we evaluate the actual cost of a filter or select?.

Explain Plan - How can we estimate the cost of a filter or select?.Coherence Query Language - How can we simplify Filters to use a select like syntax.Filters - How can we select a specific set of data from a cache based on a given criteria?.The purpose of this tutorial is to examine and exercise: Coherence 3.7 introduced additional functionality to support selections but focused on performance. Coherence 3.6, introduced the Coherence Query Language or CohQL, a lightweight SQL like language for performing select type operations on caches. Prior to Coherence 3.6 developers were required to perform queries against caches using a filtering mechanism which, while concise and efficient, required a fair amount of developer effort to code correctly.