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Grid search indexing
You should index data for the performance reasons. Indexing is a process of “materializing” complex data
in needed scopes to avoid problems of reading it.
Index data can be always re-created from the original data using certain algorithm.
You can extend the current indexer declaration with an optional <fieldset> element.
fieldset - container for field nodes, which specifies handler for processing nested field nodes.
field - concrete field processor.
filter - any optional pre-processing of data before getting to index.