Use of Standard, Compact & Compound Index Files in FoxPro

• Microsoft FoxPro for MS-DOS, versions 1.0, 1.01, 1.02, 2.0, and 2.5
• Microsoft FoxPro for Windows, version 2.5
• Microsoft FoxBASE+ for MS-DOS, versions 1.21, 2.0, 2.1, and 2.17

SUMMARY

Microsoft FoxPro uses three types of indexes: standard, compact, and compound. The information below describes the three types of indexes and their uses.

MORE INFORMATION

Microsoft FoxPro versions 1.x for MS-DOS and Microsoft FoxBASE+ versions 1.x and 2.x for MS-DOS use standard .IDX index files. FoxPro supports this index format for compatibility with the earlier products.

Compact indexes, both .CDX and .IDX indexes, are compressed, which makes them up to one-sixteenth the size of a standard .IDX index. Because a compact index is smaller, it can be processed much more quickly. These files are also known as an "individual" indexes because each file contains only one index.

Compound .CDX indexes contain multiple index entries called tags. Each tag is a separate index in the file. A compound .CDX file requires only one file handle for all of its indexes. This can help conserve system resources in a large project.

NOTE: FoxPro automatically opens a special .CDX file, the structural compound index, when it opens a database file. By default, the structural compound index has the same name as its associated database file.