RDB$INDICES

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RDB$INDICES defines the index structures that allow InterBase to locate rows in the database more quickly. Because InterBase provides both simple indexes (a single-key column) and multi-segment indexes (multiple-key columns), each index defined in this table must have corresponding occurrences in the RDB$INDEX_SEGMENTS table.

RDB$INDICES
Column name	Data type	Length	Description
`RDB$INDEX_NAME`	`CHAR`	67	Names the index being defined; if the value of this column changes, change its value in the `RDB$INDEX_SEGMENTS` table.
`RDB$RELATION_NAME`	`CHAR`	67	Names the table associated with this index; the table must be defined in the `RDB$RELATIONS` table.
`RDB$INDEX_ID`	`SMALLINT`		Contains an internal identifier for the index being defined; do not write to this column.
`RDB$UNIQUE_FLAG`	`SMALLINT`		Specifies whether the index allows duplicate values. Values: 0 - allows duplicate values 1 - does not allow duplicate values Eliminate duplicates before creating a unique index.
`RDB$DESCRIPTION`	`BLOB`		Subtype Text: User-written description of the index.
`RDB$SEGMENT_COUNT`	`SMALLINT`		Number of segments in the index; a value of 1 indicates a simple index.
`RDB$INDEX_INACTIVE`	`SMALLINT`		Indicates whether the index is: Active (value of 0) Inactive (value of 1) This is not set for system tables.
`RDB$INDEX_TYPE`	`SMALLINT`		Contains an internal identifier for sort order, either ascending (ASC) or descending (DESC): ASC (value of 0) DESC (value of 1)
`RDB$FOREIGN_KEY`	`CHAR`	67	Name of `FOREIGN KEY` constraint for which the index is implemented.
`RDB$SYSTEM_FLAG`	`SMALLINT`		Indicates whether the index is: User-defined (value of 0) System-defined (value greater than 0)
`RDB$EXPRESSION_BLR`	`BLOB`		Subtype BLR: Contains the BLR (Binary Language Representation) for the expression, evaluated by the database at execution time; used for PC semantics.
`RDB$EXPRESSION_SOURCE`	`BLOB`		Subtype Text: Contains original text source for the column; used for PC semantics.
`RDB$STATISTICS`	`DOUBLE<br/> PRECISION`		Selectivity factor for the index; the optimizer uses index selectivity, a measure of uniqueness for indexed columns, to choose an access strategy for a query.
RDB$INDEX_SPLIT_NULL	SMALLINT		Indicates if index should store NULL keys in different buckets.