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ddlStructure() - create structure for keyed field(s)

Version 7.11

ddlStructure() - create structure for keyed field(s)

Prototype:

   void ddlStructure(
      CONTROL *ctl,
      char *OptnStr,
      char *ArgList);

Permitted values in OptnStr:

/A - Automatically determine the optimum stategy for STRUCTURE /Cnnn - Low cardinality STRUCTURE

Form of ArgList:
      [<keyname1> [<keyname2>] ...]

Description:

ddlStructure() performs initial build and incremental build for all types of indexes. ddlStructure() with the /Cnnn option is optimized for low-cardinality indexes. It is substantially faster than the default ddlStructure(). And it allows multiple indexes to be built with a single pass of the data. Cardinality refers to the uniqueness quality of the key; that is, the number of unique values in the index. Form2 gives excellent performance up to an aggregate cardinality of 50,000 or more. The only qualification is that it requires approximately 8K bytes of memory times the maximum cardinality. The parameter nnn is an estimate of the maximum aggregate cardinality. In earlier versions of Thunderbolt, there was no forgiveness if this value was exceeded. However, in the current version, the required resources are automatically adjusted if this value is exceeded. The STRUCTURE Command requires access to all tables in a data base. It will fail if it is used with an Application Interface in which the view has been restricted with the "DATA GROUPS ARE ..." declaration.

Values returned in Control Structure:

Control.Ans1	+1 for each key that is successfully structured, or is empty, or is already fully structured.
Control.Ans2	Number of keys attempted to structure.

STRUCTURE Usage

STRUCTURE Vs CONSTRUCT

Advanced ddlStructure() API Functionality

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