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By default, the preferred segment modes (see Index segment modes) sort in ascending order. This can be changed to descending sort order by OR-ing CTSEG_DESCENDING with the segment mode. If a custom sort order is desired, OR the segment mode with CTSEG_ALTSEG instead.
The preferred segment modes make c-treeDB-based tables fully compatible with ISAM/Low-Level applications and/or FairCom DB SQL applications.
c-treeDB Segment Modes |
c-treeDB .NET |
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|---|---|---|
CTSEG_SCHSEG |
SCHSEG_SEG |
Absolute field number |
CTSEG_USCHSEG |
USCHSEG_SEG |
Absolute field number - uppercase |
CTSEG_VSCHSEG |
VSCHSEG_SEG |
Absolute field number - pad strings |
CTSEG_UVSCHSEG |
UVSCHSEG_SEG |
Absolute field number - pad strings upper |
CTSEG_SCHSRL |
SCHSRL_SEG |
Absolute field number - auto increment |
CTSEG_DESCENDING |
DESCENDING_SEG |
Descending segment mode |
CTSEG_ALTSEG |
ALTSEG_SEG |
Alternative collating sequence |
CTSEG_ENDSEG |
ENDSEG_SEG |
END segment mode |
CTSEG_BITSEG |
(none) |
Bitmask segment: soffset holds field number of null bit mask; slength holds field number of target field |
CTSEG_ALLNULLDUPSEG |
(none) |
Allow duplicate key values when all of the indexed fields are NULL |
CTSEG_ANYNULLDUPSEG |
(none) |
Allow duplicate key values when any of the indexed fields are NULL |
The other segment modes are kept for compatibility with existing FairCom DB applications. Advanced c-treeDB functions like ctdbAlterTable() may not work properly if the segment mode is not one of the preferred segment modes.
You may specify these segment modes with ctdbAddSegmentEx(), which expects an absolute record offset where the segment is to start (instead of a field indicator), the length in bytes of the segment, and the segment mode.
c-treeDB Segment Modes |
c-treeDB .NET |
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|---|---|---|
CTSEG_REGSEG |
REGSEG_SEG |
Absolute byte offset - No transformation |
CTSEG_INTSEG |
INTSEG_SEG |
Absolute byte offset - unsigned int/long |
CTSEG_UREGSEG |
UREGSEG_SEG |
Absolute byte offset - uppercase |
CTSEG_SRLSEG |
SRLSEG_SEG |
Absolute byte offset - auto increment |
CTSEG_VARSEG |
VARSEG_SEG |
Relative field number |
CTSEG_UVARSEG |
UVARSEG_SEG |
Relative field number - uppercase |
CTSEG_SGNSEG |
SGNSEG_SEG |
Absolute byte offset - signed int/long |
CTSEG_FLTSEG |
FLTSEG_SEG |
Absolute byte offset - float/double |
CTSEG_DECSEG |
DECSEG_SEG |
Absolute byte offset - not yet implemented |
CTSEG_BCDSEG |
BCDSEG_SEG |
Absolute byte offset - not yet implemented |
CTSEG_DESCENDING |
DESCENDING_SEG |
Descending segment mode |
CTSEG_ALTSEG |
ALTSEG_SEG |
Alternative collating sequence |
c-treeDB .NET Segment Modes are defined in the SET_MODE enum.
See also Index segment modes.
