Procedure

     EKDELR ( EK, delete record from segment )

     SUBROUTINE EKDELR ( HANDLE, SEGNO, RECNO )

Abstract

     Delete a specified record from a specified E-kernel segment.

Required_Reading

     EK

Keywords

     PRIVATE
     UTILITY

Declarations

     IMPLICIT NONE

     INCLUDE 'ekbool.inc'
     INCLUDE 'ekcoldsc.inc'
     INCLUDE 'ekcnamsz.inc'
     INCLUDE 'eksegdsc.inc'
     INCLUDE 'ektype.inc'

     INTEGER               HANDLE
     INTEGER               SEGNO
     INTEGER               RECNO

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     HANDLE     I   File handle.
     SEGNO      I   Segment number.
     RECNO      I   Record number.

Detailed_Input

     HANDLE   is a file handle of an EK open for write access.

     SEGNO    is the number of the segment from which to
              delete the specified record.

     RECNO    is the index of the record to delete. RECNO must
              be in the range 1 : NREC, where NREC is the
              number of records in the segment prior to the
              insertion.

Detailed_Output

     None. See the $Particulars section for a description of the
     effect of this routine.

Parameters

     None.

Exceptions

     1)  If HANDLE is invalid, an error is signaled by a routine in the
         call tree of this routine. The file will not be modified.

     2)  If SEGNO is out of range, the error SPICE(INVALIDINDEX)
         is signaled. The file will not be modified.

     3)  If RECNO is out of range, the error SPICE(INVALIDINDEX)
         is signaled. The file will not be modified.

     4)  If an I/O error occurs while reading or writing the indicated
         file, the error is signaled by a routine in the call tree of
         this routine. The file may be corrupted.

Files

     See the EK Required Reading ek.req for a discussion of the EK file
     format.

Particulars

     This routine operates by side effects: it deletes a record
     from an EK segment. Deleting a record implies:

        1) All column entries in the record are deleted.

        2) Link counts are decremented for data pages containing
           column entries in the record to be deleted. Pages whose
           link counts drop to zero are freed.

        3) All column indexes are updated for the parent segment.

        4) The link count is decremented for the page containing the
           record pointer structure of the record to be deleted. If
           the link count drops to zero, the page is freed.

        5) The pointer to the deleted record is deleted from the
           record tree for the parent segment.

        6) The segment's metadata is updated to reflect the new
           record count.

Examples

     1)  Suppose the second segment of an EK file designated by
         HANDLE contains 5 records:

            +-----------------+
            |     Record 1    |
            +-----------------+
            |     Record 2    |
            +-----------------+
            |     Record 3    |
            +-----------------+
            |     Record 4    |
            +-----------------+
            |     Record 5    |
            +-----------------+

         Then the call

            CALL EKDELR ( HANDLE, 2, 3 )

         deletes the third record from the segment, leaving the
         segment's contents as follows:

            +-----------------+
            |     Record 1    |
            +-----------------+
            |     Record 2    |
            +-----------------+
            |     Record 4    |
            +-----------------+
            |     Record 5    |
            +-----------------+

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)

Version

    SPICELIB Version 1.1.0, 26-MAY-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.0.0, 19-DEC-1995 (NJB)