Retrieving info about a secondary index

OpenIndex()

Retrieve basic info about a secondary index defined for a data dictionary

SYNTAX

OpenIndex(pathname, indexnum, indexname, nfields, propnames, propvalues)

Retrieve information about a data dictionary file secondary index. The information retrieved is for the index as a whole. To retrieve information relating to individual fields in the index, use the IndexFieldProp() function.

pathname	The path of the data dictionary (.d) file.
indexnum	The number of the index, where 1 represents the first secondary index defined, 2 represents the second, etc.
indexname	The index name is returned in this field, which should be alphanumeric.
nfields	The number of fields in the index is returned in this field, which should be a u (unsigned) or i (integer) type.
propnames	Alphanumeric array of 3 elements. The array is filled with the index property names - “include nulls, ”open status” and “usage”. This argument may be NULL.
propvalues	Alphanumeric array of 3 elements. This array is filled with the index property values. 1 Include record with all key fields blank (0=false, 1=true) 2 Open and close index with main index, rather than only as needed (0=false, 1=true) 3 Usage - free text descriptive comment

The function returns 0 if the file was successfully read, otherwise -1. Possible reasons for failure include permissions, file does not exist, index with this number doesn’t exist, and bad file format.

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NOTES

• The OpenDotd() function returns general information about a data dictionary, and the FieldProp() function returns properties of a specified field in it. The IndexFieldProp() function returns properties of a specified field in a secondary index.

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EXAMPLE

Store index names in an array:

!temp NumDDFields,,i2
!temp NumDDKeys,,i2
!temp NumDDIndexes,,i2

!record IndexNamesRec {
     IndexNames,,a30[50]
}

!function GetIndexNames() {
!temp IndexNum,,i2
!temp IndexNamePath,,a255
!temp NumIndexes,,i2

     OpenDotd(DDPath, NumDDFields, NumDDKeys, NumDDIndexes)
     clear IndexNamesRec

     for (IndexNum = 1; IndexNum <= tmp.NumDDIndexes; IndexNum ++) {

     if (OpenIndex(DDPath, IndexNum, IndexNamePath) <> 0) {
          error "Unable to get information from data dictionary for index number " + tostr(IndexNum)
            break
        }

        SplitPath(IndexNamePath)
        IndexNames[IndexNum] = SplitFile
     }

     return
}

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RELATED TOPICS

OpenDotd()

FieldProp()

IndexFieldProp()

Data dictionaries

Secondary indexes

Field types and sizes