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Compact Index File Structure (.idx)

Compact Index Header Record

Byte offset

Description

00 – 03

Pointer to root node

04 – 07

Pointer to free node list ( -1 if not present)

08 – 11

Reserved for internal use

12 – 13

Length of key

14

Index options (any of the following numeric values or their sums): 1   –   a unique index 8   –   index has FOR clause 32    –   compact index format 64    –   compound index header

15

Index signature

16 – 19

Reserved for internal use

20 – 23

Reserved for internal use

24 – 27

Reserved for internal use

28 – 31

Reserved for internal use

32 – 35

Reserved for internal use

36 – 501

Reserved for internal use

502 – 503

Ascending or descending: 0    = ascending 1    = descending

504 – 505

Reserved for internal use

506 – 507

FOR expression pool length1

508 – 509

Reserved for internal use

510 – 511

Key expression pool length1

512 – 1023

Key expression pool (uncompiled)

1 This information tracks the space used in the key expression pool.

Compact Index Interior Node Record

Byte offset

Description

00 – 01

Node attributes (any of the following numeric values or their sums): a.   0 – index node b.   1 – root node c.   2 – leaf node

02 – 03

Number of keys present (0, 1 or many)

04 – 07

Pointer to node directly to left of current node (on same level, -1 if not present)

08 – 11

Pointer to node directly to right of current node (on same level; -1 if not present)

12 – 511

Up to 500 characters containing the key value for the length of the key with a four-byte hexadecimal number (stored in normal left-to-right format):

This node always contains the index key, record number and intra-index pointer.2

The key/four-byte hexadecimal number combinations will occur the number of times indicated in bytes 02 – 03.

Compact Index Exterior Node Record

00 – 01

Node attributes (any of the following numeric values or their sums): 0 – index node 1 – root node 2 – leaf node

02 – 03

Number of keys present (0, 1 or many)

04 – 07

Pointer to the node directly to the left of current node (on same level; -1 if not present)

08 – 11

Pointer to the node directly to right of the current node (on same level; -1 if not present)

12 – 13

Available free space in node

14 – 17

Record number mask

18

Duplicate byte count mask

19

Trailing byte count mask

20

Number of bits used for record number

21

Number of bits used for duplicate count

22

Number of bits used for trail count

23

Number of bytes holding record number, duplicate count and trailing count

24 – 511

Index keys and information2

2 Each entry consists of the record number, duplicate byte count and trailing byte count, all compacted. The key text is placed at the logical end of the node, working backwards, allowing for previous key entries.   

See Also

Reference

Compound Index File Structure (.cdx)

Index File Structure (.idx)

Table File Structure (.dbc, .dbf, .frx, .lbx, .mnx, .pjx, .scx, .vcx)

Table Structures of Table Files (.dbc, .frx, .lbx, .mnx, .pjx, .scx, .vcx)

Memo File Structure (.FPT)

Macro File Format (.fky)

File Extensions and File Types

Other Resources

File Structures