ekifld_c

Index Page ekifld_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 ekifld_c ( SpiceInt           handle,
                       ConstSpiceChar   * tabnam,
                       SpiceInt           ncols,
                       SpiceInt           nrows,
                       SpiceInt           cnmlen,
                       const void       * cnames,
                       SpiceInt           declen,
                       const void       * decls,
                       SpiceInt         * segno,
                       SpiceInt         * rcptrs )
#### Abstract
       Initialize a new E-kernel segment to allow fast writing.
#### Required_Reading
       EK
#### Keywords
       EK
#### Brief_I/O
       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       handle     I   File handle.
       tabnam     I   Table name.
       ncols      I   Number of columns in the segment.
       nrows      I   Number of rows in the segment.
       cnmlen     I   Length of names in in column name array.
       cnames     I   Names of columns.
       declen     I   Length of declaration strings in declaration array.
       decls      I   Declarations of columns.
       segno      O   Segment number.
       rcptrs     O   Array of record pointers.
#### Detailed_Input
       handle         is the handle of an EK file open for write access.
                      A new segment is to be created in this file.

       tabnam         is the name of the EK table to which the current
                      segment belongs.  All segments in the EK file
                      designated by handle must have identical column
                      attributes. tabnam must not exceed SPICE_EK_TNAMSZ
                      (see SpiceEK.h) characters in length.  Case is not
                      significant.  Table names must start with a letter
                      and contain only characters from the set
                      {A-Z,a-z,0-9,$,_}.

       ncols          is the number of columns in a new segment.

       nrows          is the number of rows in a new segment.  Each
                      column to be added to the segment must contain
                      the number of entries indicated by nrows.

       cnmlen,
       cnames         are, respectively, the length of the column name
                      strings in the column name array, and the base
                      address of the array itself.  The array should have
                      dimensions

                         [ncols][cnmlen]

       declen,
       decls          are, respectively, the length of the declaration
                      strings in the declaration array, and the base
                      address of the array itself.  The array should have
                      dimensions

                         [ncols][declen]

                      The Ith element of cnames and the Ith element of decls
                      apply to the Ith column in the segment.

                      Column names must not exceed SPICE_EK_CNAMSZ (see
                      SpiceEK.h) characters in length.  Case is not
                      significant.  Column names must start with a letter
                      and contain only characters from the set
                      {A-Z,a-z,0-9,$,_}.

                      The declarations are strings that contain
                      `keyword=value' assignments that define the
                      attributes of the columns to which they apply.  The
                      column attributes that are defined by a column
                      declaration are:

                         DATATYPE
                         SIZE
                         <is the column indexed?>
                         <does the column allow null values?>

                      The form of a declaration is

                         "DATATYPE  = <type>,
                          SIZE      = <size>,
                          INDEXED   = <boolean>,
                          NULLS_OK  = <boolean>"

                      For example, an indexed, scalar, integer column
                      that allows null values would have the declaration

                         "DATATYPE  = INTEGER,
                          SIZE      = 1,
                          INDEXED   = TRUE,
                          NULLS_OK  = TRUE"

                      Commas are required to separate the assignments
                      within declarations; white space is optional;
                      case is not significant.

                      The order in which the attribute keywords are
                      listed in declaration is not significant.

                      Every column in a segment must be declared.

                      Each column entry is effectively an array, each
                      element of which has the declared data type.  The
                      SIZE keyword indicates how many elements are in
                      each entry of the column in whose declaration the
                      keyword appears.  Note that only scalar-valued
                      columns (those for which SIZE = 1) may be
                      referenced in query constraints.  A size
                      assignment has the syntax

                         SIZE = <integer>

                      or
                         SIZE = VARIABLE

                      The size value defaults to 1 if omitted.

                      The DATATYPE keyword defines the data type of
                      column entries.  The DATATYPE assignment syntax
                      has any of the forms

                         DATATYPE = CHARACTER*(<length>)
                         DATATYPE = CHARACTER*(*)
                         DATATYPE = DOUBLE PRECISION
                         DATATYPE = INTEGER
                         DATATYPE = TIME

                      As the datatype declaration syntax suggests,
                      character strings may have fixed or variable
                      length.  Variable-length strings are allowed only
                      in columns of size 1.

                      Optionally, scalar-valued columns may be indexed.
                      To create an index for a column, use the assignment

                         INDEXED = TRUE

                      By default, columns are not indexed.

                      Optionally, any column can allow null values.  To
                      indicate that a column may allow null values, use
                      the assigment

                         NULLS_OK = TRUE

                      in the column declaration.  By default, null
                      values are not allowed in column entries.
#### Detailed_Output
       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.  Segment
                      numbers are used as unique identifiers by other EK
                      access routines.

       rcptrs         is an array of record pointers for the input
                      segment.  This array must not be modified by the
                      caller.

                      The array rcptrs must be passed as an input to
                      each column addition routine called while
                      writing the specified segment.

                      rcptrs must be declared with dimension nrows.
#### Parameters
       None.
#### Exceptions
       1)  If HANDLE is invalid, the error will be diagnosed by routines
           called by this routine.

       2)  If TABNAM is more than SPICE_EK_TNAMSZ characters long, the
           error is diagnosed by routines called by this routine.

       3)  If TABNAM contains any nonprintable characters, the error
           is diagnosed by routines called by this routine.

       4)  If NCOLS is non-positive, the error is diagnosed by routines
           called by this routine.

       5)  If NROWS is non-positive, the error SPICE(INVALIDCOUNT)
           is signalled.

       6)  If any column name exceeds SPICE_EK_CNAMSZ characters in length,
           the error is diagnosed by routines called by this routine.

       7)  If any column name contains non-printable characters, the
           error is diagnosed by routines called by this routine.

       8)  If a declaration cannot be understood by this routine, the
           error is diagnosed by routines called by this routine.

       9)  If an non-positive string length or element size is specified,
           the error is diagnosed by routines called by this routine.

      10)  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 prepares an EK for the creation of a new segment via
       the fast column writer routines.  After this routine is called,
       the columns of the segment are filled in by calls to the fast
       column writer routines of the appropriate data types.  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}

       When all of the columns have been added, the write operation is
       completed by a call to ekffld_c {EK, finish fast write}.

       The segment is not valid until ekffld_c has been called.

       The EK system supports only one fast write at a time.  It is
       not possible use the fast write routines to simultaneously write
       multiple segments, either in the same EK file or in different
       files.
#### 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 2.3.1, 14-AUG-2006   (EDW)

          Replace mention of ldpool_c with furnsh_c.

       -CSPICE Version 2.3.0, 12-JUL-2002 (NJB)

          Call to C2F_CreateStrArr_Sig replaced with call to C2F_MapStrArr.

       -CSPICE Version 2.2.0,  10-JAN-2002 (NJB)

          Const-qualified input arrays.  Added casts to type (void *)
          to expressions passed to free(), in order to suppress compilation
          warnings under MS Visual C++/C.

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

          Corrected parameter names giving maximum table and column name
          lengths.

       -CSPICE Version 2.1.0, 14-FEB-2000 (NJB)

           Calls to C2F_CreateStrArr replaced with calls to error-signaling
           version of this routine:  C2F_CreateStrArr_Sig.

       -CSPICE Version 2.0.0, 07-JUL-1999 (NJB)

           Output segment number segno is now mapped to C range.

       -CSPICE Version 1.0.0, 08-MAR-1999 (NJB)

           Based on SPICELIB Version 1.0.0, 25-OCT-1995 (NJB)
#### Index_Entries
       start new E-kernel segment for fast writing
       start new EK segment for fast writing
#### Link to routine ekifld_c source file ekifld_c.c

    Thu Apr 16 08:57:55 2009