Hyperstage > Running Queries in Hyperstage > About the Knowledge Grid

About the Knowledge Grid

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The Knowledge Grid is a set of Hyperstage metadata used by the Hyperstage storage engine (named Infobright) to optimize query execution. The Knowledge Grid consists of Knowledge Nodes, which are optimization data for particular tables and columns. Knowledge Nodes are stored on disk in a special directory, specified in the infobright.cnf configuration file. Knowledge Nodes can be lost without losing data integrity.

About Knowledge Node

There are four kinds of Knowledge Nodes:

  • Histogram. Used by Hyperstage to enhance the speed of most queries consisting of numerical conditions (including date/time, decimal, and so on).

    Histograms are created automatically during data load.

  • Character Map. Used by Hyperstage to enhance the speed of most queries consisting of text conditions.

    Character Maps are created automatically during data load.

  • Pack/Pack. Used to enhance joining of tables. Created or updated automatically while executing user queries.
  • Data Pack Nodes (DPN). Statistical metadata that describes the content of the Data Pack. Used to both assist in data access and in rough operations.

    DPNs are created automatically during data load.

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