IDXDesc characteristics by driver

Tags in dBASE and FoxPro production multiple index files

For index tags in dBASE production multiple index files (*.MDX) and FoxPro compressed index files (*.CDX), the IDXDesc structure requires the following elements:

TypeIDXd	Name	Value	Description
DBITBLNAME	szName	Ignored
UINT16	iIndexId	Ignored
DBINAME	szTagName	10 character name	Name for index; required
DBINAME	szFormat	Ignored
BOOL	bPrimary	FALSE	Is primary; required
BOOL	bUnique	TRUE/FALSE	Is unique; required
BOOL	bDescending	TRUE/FALSE	Is descending; required
BOOL	bMaintained	TRUE	Is maintained; required
BOOL	bSubset	TRUE/FALSE	Is subset; required
BOOL	bExpIdx	TRUE/FALSE	Is expression; must be TRUE if iFldsInKey is not supplied
UINT16	iCost	Ignored
UINT16	iFldsInKey	1	Number of fields in composite index; required if bExpIdx is FALSE
UINT16	iKeyLen	Ignored
BOOL	bOutofDate	Ignored
UINT16	iKeyExpType	Ignored
DBIKEY	aiKeyFld	Field number; required if iFldsInKey is supplied and bExpIdx is FALSE
DBIKEYEXP	szKeyExp	Expression for expression index; required if bExpIdx is set to TRUE
DBIKEYEXP	szKeyCond	Condition for subset index; required if bSubset is set to TRUE
BOOL	bCaseInsensitive	FALSE	Case-insensitive index; required
UINT16	iBlockSize	Block size in bytes; optional
UINT16	iRestrNum	Ignored
UINT16	iUnUsed[16]	Unused space

dBASE multiple index files (*.MDX) have the following general characteristics:

A production index is considered part of the family.

A production index has the same name as the table.

Up to 47 indexes are allowed in the index file.

Tags in a production index are always maintained.

A index tag can be ascending or descending.

Index subset conditions are available.

Tags in dBASE and FoxPro non-production multiple index files

For dBASE non-maintained .MDX-style indexes and FoxPro .CDX-style compressed indexes (version 2.0, 2.5, and 2.6), the IDXDesc structure has the following elements:

Type	Name	Value	Description
DBITBLNAME	szName	<any_name>.MDX except <tbl_name>.MDX or <any_name>.CDX except <tbl_name>.CDX	Index name; required
UINT16	iIndexId	Ignored
DBINAME	szTagName	Name for index; required
DBINAME	szFormat	Ignored
BOOL	bPrimary	FALSE	Is primary; required
BOOL	bUnique	TRUE/FALSE	Is unique; required
BOOL	bDescending	TRUE/FALSE	Is descending; required
BOOL	bMaintained	FALSE	Is maintained; required
BOOL	bSubset	TRUE/FALSE	Is subset; required
BOOL	bExpIdx	TRUE/FALSE	Is expression; must be TRUE if iFldsInKey is not supplied
UINT16	iFldsInKey	1	Number of fields in composite index; required if bExpIdx is FALSE
UINT16	iKeyExpType	Ignored
DBIKEY	aiKeyFld	Field number in composite index; required if iFldsInKey is supplied and bExpIdx is FALSE
DBIKEYEXP	szKeyExp	Expression for expression index; required if bExpIdx is set to TRUE
DBIKEYEXP	szKeyCond	Condition for subset index; required if bSubset is set to TRUE
BOOL	bCaseInsensitive	FALSE	Case insensitive index; required
UINT16	iBlockSize	Block size in bytes; optional
UINT16	iRestrNum	Restructure number	Restructure number
UINT16	iUnUsed[16]	Unused space

Special case, non-maintained dBASE .MDX indexes have the following characteristics:

Up to 47 indexes are allowed in a single .MDX file.

All indexes are maintained when the .MDX file is opened.

The multiple index file must be manually opened.

The multiple index file cannot have the same name as the table.

Both ascending and descending order may be used.

Index subset conditions are available.

Both the index name and the tag name are required to use the index.

Naming convention: <any_name>.MDX, except <tbl_name>.MDX, or <tbl_name>.11X where the table is called <tbl_name>.111.

dBASE III PLUS-style non-maintained indexes

For dBASE non-maintained .NDX style indexes, the IDXDesc structure requires the following elements:

Type	Name	Value	Description
DBITBLNAME	szName	Any 8-character name and extension. Extension is usually .NDX.	Index name; required
UINT16	iIndexId	Ignored
DBINAME	szTagName	Ignored
DBINAME	szFormat	Ignored
BOOL	bPrimary	FALSE	Is primary; required
BOOL	bUnique	TRUE/FALSE	Is unique; required
BOOL	bDescending	FALSE	Is descending; required
BOOL	bMaintained	FALSE	Is maintained; required
BOOL	bSubset	Ignored
BOOL	bExpIdx	TRUE/FALSE	Is expression; must be TRUE if iFldsInKey is not supplied
UINT16	iFldsInKey	1	Number of fields in composite index; required if bExpIdx is FALSE
UINT16	iKeyExpType	Ignored
DBIKEY	aiKeyFld	Field number; required if iFldsInKey is given and bExpIdx is FALSE
DBIKEYEXP	szKeyExp	Expression for expression index; required if bExpIdx is TRUE
DBIKEYEXP	szKeyCond	Ignored
BOOL	bCaseInsensitive	FALSE	Case-insensitive index; required
UINT16	iBlockSize	Ignored
UINT16	iRestrNum	Restructure number
UINT16	iUnUsed[16]	Unused space

dBASE non-maintained .NDX style indexes have the following general characteristics:

Each .NDX file represents one index.

The non-maintained index file always as a .NDX filename extension.

Only ascending order is allowed.

The index is maintained only when the index is explicitly opened.

Only the index name is required to use the index.

General Paradox specifications

For Paradox primary indexes (bPrimary = TRUE), the IDXDesc structure has the following elements:

Type	Name	Value	Description
DBITBLNAME	szName	Ignored
UINT16	iIndexId	Must be 0
DBINAME	szTagName	Ignored
DBINAME	szFormat	Ignored
BOOL	bPrimary	TRUE	Is primary; required
BOOL	bUnique	TRUE	Is unique; required
BOOL	bDescending	FALSE	Is descending; required
BOOL	bMaintained	TRUE	Is maintained; required
BOOL	bSubset	FALSE	Is subset; required
BOOL	bExpIdx	FALSE	Is expression; required
UINT16	iFldsInKey	1 to 16	Number of fields in composite index; required
UINT16	iKeyExpType	Ignored
DBIKEY	aiKeyFld		Array of field numbers in composite index; required
DBIKEYEXP	szKeyExp	Ignored
DBIKEYEXP	szKeyCond	Ignored
BOOL	bCaseInsensitive	FALSE	Case-insensitive index; required
UINT16	iBlockSize	Block size in bytes
UINT16	iRestrNum	Restructure number
UINT16	iUnUsed[16]	Unused space

Paradox primary indexes have the following general characteristics:

The index must start from the first field.

The index is always case-sensitive, maintained, and unique.

The following invalid settings for Paradox primary indexes (bPrimary = TRUE) return an error message to the application:

Setting	Solution
iIndexId is not set to 0	Primary ID must be is set to 0.
bUnique is set to FALSE	Must be TRUE.
bDescending is set to TRUE	Must be FALSE.
bMaintained is set to FALSE	Must be TRUE.
bSubset is set to TRUE	Must be FALSE.
bExpIdx is set to TRUE	Must be FALSE.
iFldsInKey is 0 or greater than 16	Must be 1 to 16.
aiKeyFld	BLOB fields cannot be indexed; defined fields must be available; field cannot be used more than once in index.
szKeyCond is not set to NULL	Not available.
bCaseInsensitive is set to TRUE	Must be FALSE.

Paradox 3.5 specifications

For Paradox 3.5-style indexes, the IDXDesc structure has the following elements:

Type	Name	Value	Description
DBITBLNAME	szName	Ignored
UINT16	iIndexId	Ignored
DBINAME	szTagName	Ignored
DBINAME	szFormat	Ignored
BOOL	bPrimary	FALSE	Is primary; required
BOOL	bUnique	FALSE	Is unique; required
BOOL	bDescending	FALSE	Is descending; required
BOOL	bMaintained	TRUE/FALSE	Is maintained; required
BOOL	bSubset	FALSE	Is subset; required
BOOL	bExpIdx	FALSE	Is expression; required
UINT16	iFldsInKey	1	Number of fields in index; single field only; required
UINT16	iKeyExpType	Ignored
DBIKEY	aiKeyFld	1	Array of field numbers in index; single field only; required
DBIKEYEXP	szKeyExp	Ignored
DBIKEYEXP	szKeyCond	Ignored
BOOL	bCaseInsensitive	TRUE/FALSE	Case-insensitive index; required
UINT16	iBlockSize	Block size in bytes
UINT16	iRestrNum	Restructure number
UINT16	iUnUsed[16]	Unused space

Paradox 3.5 style indexes have the following general characteristics:

Each index can have only one field.

Up to 255 indexes are allowed.

Indexes can be maintained (primary is required) or non-maintained.

The index name becomes the field name.

The index ID is used to reference the index or the field name.

If the index is maintained, it is maintained at all times. All indexes are opened when the table is opened.

The following invalid settings for Paradox 3.5 style indexes return an error message to the application:

Setting	Solution
bUnique is set to TRUE	Must be FALSE.
bDescending is set to TRUE	Must be FALSE.
bSubset is set to TRUE	Must be FALSE.
bExpIdx is set to TRUE	Must be FALSE.
iFldsInKey is 0 or greater than 1	Must be 1.
aiKeyFld	BLOB fields can’t be indexed; defined fields must be available; field cannot be used more than once in index.
bCaseInsensitive is set to TRUE	Must be FALSE.

Paradox 4-7 specifications

For Paradox 4.0, 5.0, and 7.0 style indexes, the IDXDesc structure has the following elements:

Type	Name	Value	Description
DBITBLNAME	szName	Index name; required
UINT16	iIndexId	Ignored
DBINAME	szTagName	Ignored
DBINAME	szFormat	Ignored
BOOL	bPrimary	FALSE	Is primary; required
BOOL	bUnique	FALSE	Is unique; required
BOOL	bDescending	TRUE/FALSE	Is descending; required (TRUE valid for Paradox 7.0 indexes only)
BOOL	bMaintained	TRUE/FALSE	Is maintained; required
BOOL	bSubset	FALSE	Is subset; required
BOOL	bExpIdx	FALSE	Is expression; required
UINT16	iFldsInKey	1	Number of fields in index; single field only; required
UINT16	iKeyExpType	Ignored
DBIKEY	aiKeyFld	1	Array of field numbers in index; single field only; required
DBIKEYEXP	szKeyExp	Ignored
DBIKEYEXP	szKeyCond	Ignored
BOOL	bCaseInsensitive	TRUE/FALSE	Case-insensitive index; required
UINT16	iBlockSize	Block size in bytes
UINT16	iRestrNum	Restructure number
UINT16	iUnUsed[16]	Unused space

Paradox 4.0 and 5.0 style indexes have the following general characteristics:

Both maintained (primary is required) and non-maintained indexes are allowed.

Indexes may be case-sensitive, or case-insensitive.

A composite index can have more than one field.

Only the index name is required to reference the index

Up to 320 indexes are allowed.

If the index is maintained, it is maintained at all times. All indexes are opened when the table is opened.

The following invalid settings for Paradox 4.0 and 5.0 style indexes return an error message to the application:

Setting	Solution
szName is set to NULL	Name required to find index.
bUnique is set to TRUE	Must be FALSE.
bDescending is set to TRUE	Must be FALSE.
bSubset is set to TRUE	Must be FALSE.
bExpIdx is set to TRUE	Must be FALSE.
iFldsInKey is 0 or greater than 16	Must be 1 to 16.
aiKeyFld	BLOB fields can’t be indexed; defined fields must be available; field cannot be used more than once in index.

Paradox naming conventions

The following naming conventions must be followed for Paradox indexes:

Index Type	Naming convention
Non-composite	Same as field name.
Non-composite, case-insensitive	Any legal name. Must be unique. A field name can be used if not already used by a non-composite index.
Composite	Any legal name not used as a field name. Must be unique. A field name can be used if not already used by a non-composite index.

Paradox 7.0 style indexes follow the same conventions as Paradox 4.0 and 5.0 style indexes except bDescending can be TRUE or FALSE.