Indexed file size limits

The following file size limits affect indexed files:

On Windows, the default (where IDXFORMAT=0) is IDXFORMAT 3.

On UNIX, the default is IDXFORMAT 1 (C-ISAM) for fixed record length files and IDXFORMAT 3 for variable record length files.

To create files of a different format, use the IDXFORMAT extfh.cfg or compiler directive setting. To convert existing files to other formats, use the Rebuild utility.

IDXFORMAT	Exclusive (#)	Exclusive with duplicate key compression on	Shared with default locking	FILEMAXSIZE set to
1	4 Gb	2 Gb	1 Gb	4 or 8
2	4 Gb	2 Gb	1 Gb	4 or 8
3	4 Gb	2 Gb	1 Gb	4 or 8
4	4 Gb	2 Gb	1 Gb	4 or 8
8	4 Gb	2 Gb	1 Gb	4
8	256 Tb	128 Tb	256 Tb	8

IDXFORMAT

Exclusive (#)

Exclusive with duplicate key compression on

Shared with default locking

FILEMAXSIZE set to

4 Gb

2 Gb

1 Gb

4 or 8

4 Gb

2 Gb

1 Gb

4 or 8

4 Gb

2 Gb

1 Gb

4 or 8

4 Gb

2 Gb

1 Gb

4 or 8

4 Gb

2 Gb

1 Gb

256 Tb

128 Tb

256 Tb

where:

(#) = either accessing files exclusively or accessing shared files with the extfh.cfg or compiler directive setting of LOCKTYPE 1 or 2. That is, file size is not affected when using LOCKTYPE 1 or 2.

FILEMAXSIZE is an extfh.cfg setting that defaults to 4

For IDXFORMAT 8 files only, if you increase the extfh.cfg setting FILEPOINTERSIZE to 8, you increase file size limits to:

IDXFORMAT	Exclusive (#)	Exclusive with duplicate key compression on	Shared with default locking	FILEMAXSIZE set to
8	16 Eb	8 Eb	4 Eb	8

Notes:

The above figures are determined by the pointer size used to address the file. For example:

32 bits	=	2^32	=	4,294,967,296 bytes	=	4 Gb (Gigabytes)
48 bits	=	2^48	=	281,474,976,710,656 bytes	=	256 Tb (Terabytes)
64 bits	=	2^64	=	18,446,744,073,709,551,616 bytes	=	16 Eb (Exabytes or MegaTerabytes)

LOCKTYPE settings of 1 and 2 were specifically introduced in order to avoid the file size limit imposed by sharing files.
If you set FILEMAXSIZE to 8, IDXFORMAT 8 supports very large files with the default locking mechanism. Therefore, you are recommended to use IDXFORMAT 8 for large files rather than any of the other formats which also require LOCKTYPE 1 or 2 for large files. (LOCKTYPE=1 has the disadvantage of not allowing locked data to be read at all while LOCKTYPE=2 has the disadvantage of using up an extra file handle for the .LCK file that contains the locks).

Indexed File Size Limits