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Design Guide

Design Guide

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Identity Index Definition

Identity Index Definition

This begins with the

IDX-DEFINITION

keyword and defines an IIR Identity Index. The fields are as follows:

Field	Description
NAME=	A character string that specifies the name of the IDX. The maximum length is 32 bytes. This is a mandatory parameter.
COMMENT=	A free-form description of this IDX
ID=	A two-letter character string used to generate the names of the actual database table that represents the IDX. Each IDX must have a unique table name (generated from the target database’s userid (schema), System Qualifier, and ID). Refer to the OPERATIONS guide, Database Object Names section for details. This is a mandatory parameter.
IDT-NAME=	The name of the IDT Table that this IDX belongs to (as defined in the File-Definition or User-Source-Table sections). This is a mandatory parameter. If you intend to use the AnswerSet feature with this IDT, then this name may need to be kept short so that the name of the AnswerSet table does not exceed maximum length supported by the host DBMS. Refer to the DEVELOPER GUIDE, AnswerSet section for details.
AUTO-ID-FIELD=	This field is not required if loading data from a User Source Table. The name of a field defined in the Files section that contains a unique record label referred to as the Record Source If no such field exists in the IDT, IIR can generate one (see AUTO-ID and AUTO-ID-NAME parameters). If IIR is being asked to generate an Id, the user can choose the name of the AUTO-ID-FIELD , however that name must be defined as a field in the Files section (if using a transform clause, this happens automatically).
KEY-LOGIC=	This parameter describes the key-logic to be used to generate keys for the IDX. It may differ from the Search-Logic used to search the IDX. Refer to the Key Logic section for details. This is a mandatory parameter.
PARTITION=(field [, length , offset [, null-partition-value]]),. . .	This option instructs Identify Resolution to build a concatenated key from the Key-Field, which is defined by KEY-LOGIC= and up to five fields or sub-fields taken from the record. For large files, the key might not be selective enough because it retrieves too many records. The field, length, and offset represent the field name, number of bytes to concatenate to the key and offset into the field (starting from 0) respectively. The length and offset are optional. If omitted, the entire field is used. Use null-partition-value , which defaults to spaces, to specify a value for an empty field. If you specify the NO-NULL-PARTITION option, it can ignore the records that contain a null partition value. For the NO-NULL-PARTITION option to work, all the values of the specified fields must be null. Partition values are case sensitive. Data might be mono-cased using a transform when loading the data. Be sure to use the correct case when entering search data. For non-displayable data, the value might be specified in hexadecimal notation in the form: hex(hexadecimal value) .
OPTIONS=	Specifies options to control the keys and data stored in the IDX. The supported options are as follows: ALT . Stores alternate keys in the IDX. This option is on by default. When disabled ( --Alt ) only the first key from the key-stack is stored in the IDX. FULL-KEY-DATA . Stores all IDT fields in the IDX. This is the default. The data is stored in uncompressed form unless you specify the Compress-Key-Data option. FULL-KEY-DATA . Stores all IDT fields in the IDX. This is the default. The data is stored in uncompressed form unless you specify the Compress-Key-Data option. COMPRESS-KEY-DATA(n) . Stores all IDT fields in compressed form using a fixed record length of n bytes. n can not exceed (m - PartitionLength - KeyLength - 4) where m=255 for Oracle and m=250 for UDB. Selecting the appropriate value for n is discussed in the Compressed Key Data section. COMPRESS-METHOD(n) . Overrides the default set by the System Options that specify the compression method to use when storing Compressed-Key-Data. Method 0 (the default) will store records longer than 255 bytes as multiple adjacent IDX records. This improves performance as it takes advantage of the locality of reference in the DBMS’ cache. Method 1 . Truncates the IDX records if their size exceeds 255 bytes and fetch them from the IDT instead. This causes additional I/O when truncated IDX records are referenced. LITE . Creates a Lite Index. See the Key Logic section for more information. NO-NULL-FIELD . Does not store IDX entries for rows that contain a Null-Field. A Null-Field is defined in the Key-Logic section. NO-NULL-KEY . Does not store Null-Keys in the IDX. A Null-Key is defined in the Key-Logic section. NO-NULL-PARTITION . Does not store keys in the IDX that contains null-partition-value , as defined by the PARTITION= keyword.

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