This repository has been archived. Please see MonetDB/e (code examples here) for the replacement project.

MonetDBLite for C

MonetDBLite is an embedded SQL database that runs inside another program and does not require the installation of any external software. MonetDBLite is based on free and open-source MonetDB, a product of the Centrum Wiskunde & Informatica.

MonetDBLite is similar in functionality to SQLite, but optimized for analytical (OLAP) use cases.

Build Process

Installation from source is a matter of typing

make -j

This produces a shared library file libmonetdb5.(so|dll|dylib) in the build/ folder, which contains all required code to run MonetDBLite. This library can then be linked to by your software. On Windows, we use the MinGW-64 toolchains (32 bit, 64 bit (recommended)) and the mingw32-make tool to build the DLL.

Usage Example

See src/embedded/embedded.h for the full API. Here a quick example

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

#define error(msg) {fprintf(stderr, "Failure: %s\n", msg); return -1;}

int main(void) {
    char* err = 0;
    void* conn = 0;
    monetdb_result* result = 0;
    size_t r, c;

    // first argument is a string for the db directory or NULL for in-memory mode
    err = monetdb_startup(NULL, 0, 0);
    if (err != 0)
        error(err)

    conn = monetdb_connect();
    if (conn == NULL)
        error("Connection failed")

    err = monetdb_query(conn, "CREATE TABLE test (x integer, y string)", 1,
    NULL, NULL, NULL);
    if (err != 0)
        error(err)

    err = monetdb_query(conn,
            "INSERT INTO test VALUES (42, 'Hello'), (NULL, 'World')", 1, NULL,
            NULL, NULL);
    if (err != 0)
        error(err)

    err = monetdb_query(conn, "SELECT x, y FROM test; ", 1, &result, NULL,
    NULL);
    if (err != 0)
        error(err)

    fprintf(stdout, "Query result with %d cols and %d rows\n", (int) result->ncols,
            (int) result->nrows);

    for (r = 0; r < result->nrows; r++) {
        for (c = 0; c < result->ncols; c++) {
            monetdb_column* rcol = monetdb_result_fetch(result, c);
            switch (rcol->type) {
            case monetdb_int32_t: {
                monetdb_column_int32_t * col = (monetdb_column_int32_t *) rcol;
                if (col->data[r] == col->null_value) {
                    printf("NULL");
                } else {
                    printf("%d", (int) col->data[r]);
                }
                break;
            }
            case monetdb_str: {
                monetdb_column_str * col = (monetdb_column_str *) rcol;
                if (col->is_null(col->data[r])) {
                    printf("NULL");
                } else {
                    printf("%s", (char*) col->data[r]);
                }
                break;
            }
            default: {
                printf("UNKNOWN");
            }
            }

            if (c + 1 < result->ncols) {
                printf(", ");
            }
        }
        printf("\n");
    }

    monetdb_cleanup_result(conn, result);
    monetdb_disconnect(conn);
    monetdb_shutdown();
    return 0;
}

You can build and link this example program with the MonetDBLite shared library (for example) as follows

gcc tests/readme/readme.c -o readme -Isrc/embedded -Lbuild -lmonetdb5

This should produce a binary named readme. Running this binary should produce the following output:

Query result with 2 cols and 2 rows
42, Hello
NULL, World

Issues

If you encounter a bug, please file a minimal reproducible example on github. For questions and other discussion, please use stack overflow with the tag monetdblite.