ekffld_c

Index Page ekffld_c
A B C D E F G H I J K L M N O P Q R S T U V W X
Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries
#### Procedure
       void ekffld_c ( SpiceInt     handle,
                       SpiceInt     segno,
                       SpiceInt   * rcptrs )
#### Abstract
       Complete a fast write operation on a new E-kernel segment.
#### Required_Reading
       EK
#### Keywords
       EK
#### Brief_I/O
       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       handle     I   File handle.
       segno      I   Segment number.
       rcptrs     I   Record pointers.
#### Detailed_Input
       handle         the handle of an EK file that is open for writing.
                      A "begin segment for fast write" operation must
                      have already been performed for the designated
                      segment.

       segno          is the number of the segment to which data is to be
                      added. Segments are numbered from 0 to nseg-1, where
                      nseg is the count of segments in the file.

       rcptrs         is an array of record pointers for the input
                      segment.  This array is obtained as an output
                      from ekifld_c, the routine called to initiate a
                      fast write.
#### Detailed_Output
       None.

       See the Particulars section for a description of the
       effects of this routine.
#### Parameters
       None.
#### Exceptions
       1)  If handle is invalid, the error will be diagnosed by routines
           called by this routine.

       2)  If an attempt is made to finish a segment other than the
           one last initialized by ekifld_c, the error will be diagnosed by
           routines called by this routine.

       3)  If an I/O error occurs while reading or writing the indicated
           file, the error will be diagnosed by routines called by this
           routine.
#### Files
       See the EK Required Reading for a discussion of the EK file
       format.
#### Particulars
       This routine completes an EK segment after the data has been
       written via the fast column writer routines.  The segment must
       have been created by a call to elifld_c.  The fast column
       writer routines are:

          ekaclc_c {EK, add column, character}
          ekacld_c {EK, add column, double precision}
          ekacli_c {EK, add column, integer}

       The segment is not guaranteed to be readable until all columns
       have been added.  After the columns have been added, the segment
       may be extended by inserting more records and filling in those
       records using the ekaceX_c routines.
#### Examples
       1)  Suppose we have an E-kernel named order_db.ek which contains
           records of orders for data products.  The E-kernel has a
           table called DATAORDERS that consists of the set of columns
           listed below:

              DATAORDERS

                 Column Name     Data Type
                 -----------     ---------
                 ORDER_ID        INTEGER
                 CUSTOMER_ID     INTEGER
                 LAST_NAME       CHARACTER*(*)
                 FIRST_NAME      CHARACTER*(*)
                 ORDER_DATE      TIME
                 COST            DOUBLE PRECISION

           The order database also has a table of items that have been
           ordered.  The columns of this table are shown below:

              DATAITEMS

                 Column Name     Data Type
                 -----------     ---------
                 ITEM_ID         INTEGER
                 ORDER_ID        INTEGER
                 ITEM_NAME       CHARACTER*(*)
                 DESCRIPTION     CHARACTER*(*)
                 PRICE           DOUBLE PRECISION

           We'll suppose that the file ORDER_DB.EK contains two segments,
           the first containing the DATAORDERS table and the second
           containing the DATAITEMS table.

           Below, we show how we'd open a new EK file and create the
           first of the segments described above.

           #include "SpiceUsr.h"
           #include <stdio.h>

           void main()
           {
              /.
              Constants
              ./
              #define  CNMLEN      ( CSPICE_EK_COL_NAM_LEN + 1 )
              #define  DECLEN        201
              #define  EKNAME        "order_db.ek"
              #define  FNMLEN        50
              #define  IFNAME        "Test EK/Created 20-SEP-1995"
              #define  LNMLEN        50
              #define  LSK           "leapseconds.ker"
              #define  NCOLS         6
              #define  NRESVC        0
              #define  NROWS         9
              #define  TABLE         "DATAORDERS"
              #define  TNMLEN        CSPICE_EK_TAB_NAM_LEN
              #define  UTCLEN        30

              /.
              Local variables
              ./
              SpiceBoolean            nlflgs [ NROWS  ];

              SpiceChar               cdecls  [ NCOLS ] [ DECLEN ];
              SpiceChar               cnames  [ NCOLS ] [ CNMLEN ];
              SpiceChar               fnames  [ NROWS ] [ FNMLEN ];
              SpiceChar               lnames  [ NROWS ] [ LNMLEN ];
              SpiceChar               dateStr [ UTCLEN ];

              SpiceDouble             costs  [ NROWS ];
              SpiceDouble             ets    [ NROWS ];

              SpiceInt                cstids [ NROWS ];
              SpiceInt                ordids [ NROWS ];
              SpiceInt                handle;
              SpiceInt                i;
              SpiceInt                rcptrs [ NROWS ];
              SpiceInt                segno;
              SpiceInt                sizes  [ NROWS ];
              SpiceInt                wkindx [ NROWS ];

              /.
              Load a leapseconds kernel for UTC/ET conversion.
              ./
              furnsh_c ( LSK );

              /.
              Open a new EK file.  For simplicity, we will not
              reserve any space for the comment area, so the
              number of reserved comment characters is zero.
              The constant IFNAME is the internal file name.
              ./
              ekopn_c ( EKNAME, IFNAME, NRESVC, &handle );

              /.
              Set up the table and column names and declarations
              for the DATAORDERS segment.  We'll index all of
              the columns.  All columns are scalar, so we omit
              the size declaration.  Only the COST column may take
              null values.
              ./
              strcpy ( cnames[0], "ORDER_ID"                           );
              strcpy ( cdecls[0], "DATATYPE = INTEGER, INDEXED = TRUE" );

              strcpy ( cnames[1], "CUSTOMER_ID"                        );
              strcpy ( cdecls[1], "DATATYPE = INTEGER, INDEXED = TRUE" );

              strcpy ( cnames[2], "LAST_NAME"                          );
              strcpy ( cdecls[2], "DATATYPE = CHARACTER*(*),"
                                  "INDEXED  = TRUE"                    );

              strcpy ( cnames[3], "FIRST_NAME"                         );
              strcpy ( cdecls[3], "DATATYPE = CHARACTER*(*),"
                                  "INDEXED  = TRUE"                    );

              strcpy ( cnames[4], "ORDER_DATE"                         );
              strcpy ( cdecls[4], "DATATYPE = TIME, INDEXED  = TRUE"   );

              strcpy ( cnames[5], "COST"                               );
              strcpy ( cdecls[5], "DATATYPE = DOUBLE PRECISION,"
                                  "INDEXED  = TRUE,"
                                  "NULLS_OK = TRUE"                    );

              /.
              Start the segment.  We presume the number of  rows
              of data is known in advance.
              ./
              ekifld_c ( handle,  TABLE,   NCOLS,  NROWS,   CNMLEN,
                         cnames,  DECLEN,  cdecls, &segno,  rcptrs );

              /.
              At this point, arrays containing data for the
              segment's columns may be filled in.  The names
              of the data arrays are shown below.

                 Column           Data array

                 "ORDER_ID"       ordids
                 "CUSTOMER_ID"    cstids
                 "LAST_NAME"      lnames
                 "FIRST_NAME"     fnames
                 "ORDER_DATE"     odates
                 "COST"           costs

              The null flags array indicates which entries are null.
              It is ignored for columns that don't allow null
              values.  In this case, only the COST column allows
              nulls.

              Fill in data arrays and null flag arrays here.  This code
              section would normally be replaced by calls to user functions
              returning column values.
              ./

              for ( i = 0;  i < NROWS;  i++ )
              {
                 ordids[i]  =  i;
                 cstids[i]  =  i*100;
                 costs [i]  =  (SpiceDouble) 100*i;

                 sprintf  ( fnames[i], "Order %d Customer first name", i );
                 sprintf  ( lnames[i], "Order %d Customer last name",  i );
                 sprintf  ( dateStr,   "1998 Mar %d",                  i );

                 utc2et_c ( dateStr, ets+i );

                 nlflgs[i]  =  SPICEFALSE;
              }

              nlflgs[1] = SPICETRUE;

              /.
              The sizes array shown below is ignored for scalar
              and fixed-size array columns, so we need not
              initialize it.  For variable-size arrays, the
              Ith element of the sizes array must contain the size
              of the Ith column entry in the column being written.
              Normally, the sizes array would be reset for each
              variable-size column.

              Add the columns of data to the segment.  All of the
              data for each column is written in one shot.
              ./
              ekacli_c ( handle,  segno,   "order_id",    ordids,
                         sizes,   nlflgs,  rcptrs,        wkindx );

              ekacli_c ( handle,  segno,   "customer_id", cstids,
                         sizes,   nlflgs,  rcptrs,        wkindx );

              ekaclc_c ( handle,  segno,   "last_name",   LNMLEN,
                         lnames,  sizes,   nlflgs,        rcptrs,  wkindx );

              ekaclc_c ( handle,  segno,   "first_name",  FNMLEN,
                         fnames,  sizes,   nlflgs,        rcptrs,  wkindx );

              ekacld_c ( handle,  segno,   "order_date",  ets,
                         sizes,   nlflgs,  rcptrs,        wkindx );

              ekacld_c ( handle,  segno,   "cost",        costs,
                         sizes,   nlflgs,  rcptrs,        wkindx );

              /.
              Complete the segment.  The rcptrs array is that
              returned by ekifld_c.
              ./
              ekffld_c ( handle, segno, rcptrs );

              /.
              At this point, the second segment could be
              created by an analogous process.  In fact, the
              second segment could be created at any time; it is
              not necessary to populate the first segment with
              data before starting the second segment.

              The file must be closed by a call to ekcls_c.
              ./
              ekcls_c ( handle );
           }
#### Restrictions
       1)  Only one segment can be created at a time using the fast
           write routines.

       2)  No other EK operation may interrupt a fast write.  For
           example, it is not valid to issue a query while a fast write
           is in progress.
#### Literature_References
       None.
#### Author_and_Institution
       N.J. Bachman   (JPL)
#### Version
       -CSPICE Version 2.0.2, 14-AUG-2006   (EDW)

          Replace mention of ldpool_c with furnsh_c.

       -CSPICE Version 2.0.1, 09-JAN-2002 (NJB)

          Documentation change:  instances of the phrase "fast load"
          were replaced with "fast write."

       -CSPICE Version 2.0.0, 07-JUL-1998 (NJB)

          Segment number is now mapped from C to Fortran range.

       -CSPICE Version 1.0.0, 01-APR-1998 (NJB)

          Based on SPICELIB Version 1.0.1, 31-MAR-1998 (NJB)
#### Index_Entries
       finish a fast EK segment write
#### Link to routine ekffld_c source file ekffld_c.c

    Thu Apr 16 08:57:53 2009