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 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
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