ex_schema.c

Shows how to create column-oriented data and access individual columns.

/*-
 * Public Domain 2008-2012 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * ex_schema.c
 *      This is an example application demonstrating how to create and access
 *      tables using a schema.
 */

#include <stdio.h>
#include <string.h>

#include <inttypes.h>
#include <wiredtiger.h>

const char *home = "WT_TEST";

/* The C struct for the data we are storing with WiredTiger. */
typedef struct {
        char country[5];
        uint16_t year;
        uint64_t population;
} POP_RECORD;
POP_RECORD pop_data[] = {
        { "USA", 1980, 226542250 },
        { "USA", 2009, 307006550 },
        { "UK", 2008, 61414062 },
        { "CAN", 2008, 33311400 },
        { "AU", 2008, 21431800 }
};

int main(void)
{
        int ret;
        WT_CONNECTION *conn;
        WT_SESSION *session;
        WT_CURSOR *cursor;
        POP_RECORD *p, *endp;
        const char *country;
        uint64_t recno;
        uint16_t year;

        ret = wiredtiger_open(home, NULL, "create", &conn);
        if (ret != 0)
                fprintf(stderr, "Error connecting to %s: %s\n",
                    home, wiredtiger_strerror(ret));
        /* Note: error checking omitted for clarity. */

        ret = conn->open_session(conn, NULL, NULL, &session);

        /*
         * Create the population table.
         * Keys are record numbers, the format for values is
         * (5-byte string, short, long).
         * See ::wiredtiger_struct_pack for details of the format strings.
         *
         * If this program is run multiple times so the table already exists,
         * this call will verify that the table exists.  It is not required in
         * that case, but is a safety check that the schema matches what the
         * program expects.
         */
        ret = session->create(session, "table:population",
            "key_format=r,"
            "value_format=5sHQ,"
            "columns=(id,country,year,population),"
            "colgroups=(main,population)");

        /* Create the column groups to store population in its own file. */
        ret = session->create(session, "colgroup:population:main",
            "columns=(country,year)");

        ret = session->create(session, "colgroup:population:population",
            "columns=(population)");

        /* Create an index with composite key (country,year). */
        ret = session->create(session, "index:population:country_year",
            "columns=(country,year)");

        ret = session->open_cursor(session, "table:population",
            NULL, "append", &cursor);

        endp = pop_data + (sizeof (pop_data) / sizeof(pop_data[0]));
        for (p = pop_data; p < endp; p++) {
                cursor->set_value(cursor, p->country, p->year, p->population);
                ret = cursor->insert(cursor);
        }
        ret = cursor->close(cursor);

        /* Now just read through the countries we know about */
        ret = session->open_cursor(session,
            "index:population:country_year(id)",
            NULL, NULL, &cursor);

        while ((ret = cursor->next(cursor)) == 0) {
                cursor->get_key(cursor, &country, &year);
                cursor->get_value(cursor, &recno);

                printf("Got country %s : row ID %d\n", country, (int)recno);
        }

        ret = conn->close(conn, NULL);
        return (ret);
}