path: root/node/ejdb.js

var ejdblib;
try {
    ejdblib = require("../build/Release/ejdb_native.node");
} catch (e) {
    ejdblib = require("../build/Debug/ejdb_native.node");
    console.error("Warning: Using the DEBUG version of EJDB nodejs binding");
}
var EJDBImpl = ejdblib.NodeEJDB;

const DEFAULT_OPEN_MODE = (ejdblib.JBOWRITER | ejdblib.JBOCREAT);
var EJDB = function(dbFile, openMode) {
    Object.defineProperty(this, "_impl", {
        value : new EJDBImpl(dbFile, (openMode > 0) ? openMode : DEFAULT_OPEN_MODE),
        configurable : false,
        enumerable : false,
        writable : false
    });
    return this;
};

for (var k in ejdblib) { //Export constants
    if (k.indexOf("JB") === 0) {
        EJDB[k] = ejdblib[k];
    }
}
EJDB.DEFAULT_OPEN_MODE = DEFAULT_OPEN_MODE;

/**
 * Open database.
 * Return database instance handle object .
 *
 * Default open mode: JBOWRITER | JBOCREAT
 *
 * This is blocking function.
 *
 * @param {String} dbFile Database main file name
 * @param {Number} [openMode=JBOWRITER | JBOCREAT] Bitmast of open modes:
 *      - `JBOREADER` Open as a reader.
 *      - `JBOWRITER` Open as a writer.
 *      - `JBOCREAT` Create db if it not exists
 *      - `JBOTRUNC` Truncate db.
 * @returns {EJDB} EJDB database wrapper
 */

EJDB.open = function(dbFile, openMode) {
    return new EJDB(dbFile, openMode);
};


/**
 * Returns true if argument is valid object id (OID) string.
 * @param {String} oid Object id.
 * @return {Boolean}
 */
EJDB.isValidOID = function(oid) {
    if (typeof oid !== "string" || oid.length !== 24) {
        return false;
    }
    var i = 0;
    //noinspection StatementWithEmptyBodyJS
    for (; ((oid[i] >= 0x30 && oid[i] <= 0x39) || /* 1 - 9 */
            (oid[i] >= 0x61 && oid[i] <= 0x66)); /* a - f */
           ++i);
    return (i === 24);
};

/**
 * Close database.
 * If database was not opened it does nothing.
 *
 * This is blocking function.
 */
EJDB.prototype.close = function() {
    return this._impl.close();
};

/**
 * Check if database in opened state.
 */
EJDB.prototype.isOpen = function() {
    return this._impl.isOpen();
};

/**
 * Automatically creates new collection if it does't exists.
 * Collection options `copts`
 * are applied only for newly created collection.
 * For existing collections `copts` takes no effect.
 *
 * Collection options (copts):
 *  {
 *      "cachedrecords" : Max number of cached records in shared memory segment. Default: 0
 *      "records" : Estimated number of records in this collection. Default: 65535.
 *      "large" : Specifies that the size of the database can be larger than 2GB. Default: false
 *      "compress" : If true collection records will be compressed with DEFLATE compression. Default: false.
 *  }
 *
 * This is blocking function.
 *
 * @param {String} cname Name of collection.
 * @param {Object} [copts] Collection options.
 * @return {*}
 */
EJDB.prototype.ensureCollection = function(cname, copts) {
    return this._impl.ensureCollection(cname, copts || {});
};

/**
 *  Remove collection.
 *
 *  Call variations:
 *      - removeCollection(cname)
 *      - removeCollection(cname, cb)
 *      - removeCollection(cname, prune, cb)
 *
 * @param {String} cname Name of collection.
 * @param {Boolean} [prune=false] If true the collection data will erased from disk.
 * @param {Function} [cb] Callback function with arguments: (error)
 */
EJDB.prototype.removeCollection = function(cname, prune, cb) {
    if (arguments.length == 2) {
        cb = prune;
        prune = false;
    }
    if (!cb) {
        cb = function() {
        };
    }
    return this._impl.removeCollection(cname, !!prune, cb);
};


/**
 * Save/update specified JSON objects in the collection.
 * If collection with `cname` does not exists it will be created.
 *
 * Each persistent object has unique identifier (OID) placed in the `_id` property.
 * If a saved object does not have `_id` it will be autogenerated.
 * To identify and update object it should contains `_id` property.
 *
 * If callback is not provided this function will be synchronous.
 *
 * Call variations:
 *      - save(cname, <json object>|<Array of json objects>, options)
 *      - save(cname, <json object>|<Array of json objects>, cb)
 *      - save(cname, <json object>|<Array of json objects>, options, cb)
 *
 * @param {String} cname Name of collection.
 * @param {Array|Object} jsarr Signle JSON object or array of JSON objects to save
 * @param {Function} [cb] Callback function with arguments: (error, {Array} of OIDs for saved objects)
 * @return {Array} of OIDs of saved objects in synchronous mode otherwise returns {undefined}.
 */
EJDB.prototype.save = function(cname, jsarr, opts, cb) {
    if (!jsarr) {
        return [];
    }
    if (jsarr.constructor !== Array) {
        jsarr = [jsarr];
    }
    if (typeof opts == "function") {
        cb = opts;
        opts = null;
    }
    var postprocess = function(oids) {
        //Assign _id property for newly created objects
        for (var i = jsarr.length - 1; i >= 0; --i) {
            var so = jsarr[i];
            if (so != null && so["_id"] !== oids[i]) {
                so["_id"] = oids[i];
            }
        }
    };
    if (cb == null) {
        postprocess(this._impl.save(cname, jsarr, (opts || {})));
        return jsarr;
    } else {
        return this._impl.save(cname, jsarr, (opts || {}), function(err, oids) {
            if (err) {
                cb(err);
                return;
            }
            postprocess(oids);
            cb(null, oids);
        });
    }
};


/**
 * Loads JSON object identified by OID from the collection.
 * If callback is not provided this function will be synchronous.
 *
 * @param {String} cname Name of collection
 * @param {String} oid Object identifier (OID)
 * @param {Function} [cb]  Callback function with arguments: (error, obj)
 *        `obj`:  Retrieved JSON object or NULL if it is not found.
 * @return JSON object or {null} if it is not found in synchronous mode otherwise return {undefined}.
 */
EJDB.prototype.load = function(cname, oid, cb) {
    return this._impl.load(cname, oid, cb);
};

/**
 * Removes JSON object from the collection.
 * If callback is not provided this function will be synchronous.
 *
 * @param {String} cname Name of collection
 * @param {String} oid Object identifier (OID)
 * @param {Function} [cb]  Callback function with arguments: (error)
 * @return {undefined}
 */
EJDB.prototype.remove = function(cname, oid, cb) {
    return this._impl.remove(cname, oid, cb);
};


/*
 * - (cname, [cb])
 * - (cname, qobj, [cb])
 * - (cname, qobj, hints, [cb])
 * - (cname, qobj, qobjarr, [cb])
 * - (cname, qobj, qobjarr, hints, [cb])
 */
function parseQueryArgs(args) {
    var cname, qobj, orarr, hints, cb;
    var i = 0;
    cname = args[i++];
    if (typeof cname !== "string") {
        throw new Error("Collection name 'cname' argument must be specified");
    }
    var next = args[i++];
    if (typeof next === "function") {
        cb = next;
    } else {
        qobj = next;
    }
    next = args[i++];
    if (next !== undefined) {
        if (next.constructor === Array) {
            orarr = next;
            next = args[i++];
        } else if (typeof next === "object") {
            hints = next;
            orarr = null;
            next = args[i++];
        }
        if (!hints && typeof next === "object") {
            hints = next;
            next = args[i++];
        }
        if (typeof next === "function") {
            cb = next;
        }
    }
    return [cname, (qobj || {}), (orarr || []), (hints || {}), (cb || null)];
}

/**
 * Execute query on collection.
 *
 * EJDB queries inspired by MongoDB (mongodb.org) and follows same philosophy.
 *
 *  - Supported queries:
 *      - Simple matching of String OR Number OR Array value:
 *          -   {'json.field.path' : 'val', ...}
 *      - $not Negate operation.
 *          -   {'json.field.path' : {'$not' : val}} //Field not equal to val
 *          -   {'json.field.path' : {'$not' : {'$begin' : prefix}}} //Field not begins with val
 *      - $begin String starts with prefix
 *          -   {'json.field.path' : {'$begin' : prefix}}
 *      - $gt, $gte (>, >=) and $lt, $lte for number types:
 *          -   {'json.field.path' : {'$gt' : number}, ...}
 *      - $bt Between for number types:
 *          -   {'json.field.path' : {'$bt' : [num1, num2]}}
 *      - $in String OR Number OR Array val matches to value in specified array:
 *          -   {'json.field.path' : {'$in' : [val1, val2, val3]}}
 *      - $nin - Not IN
 *      - $strand String tokens OR String array val matches all tokens in specified array:
 *          -   {'json.field.path' : {'$strand' : [val1, val2, val3]}}
 *      - $stror String tokens OR String array val matches any token in specified array:
 *          -   {'json.field.path' : {'$stror' : [val1, val2, val3]}}
 *      - $exists Field existence matching:
 *          -   {'json.field.path' : {'$exists' : true|false}}
 *      - $icase Case insensitive string matching:
 *          -    {'json.field.path' : {'$icase' : 'val1'}} //icase matching
 *          icase matching with '$in' operation:
 *          -    {'name' : {'$icase' : {'$in' : ['tHéâtre - театр', 'heLLo WorlD']}}}
 *          For case insensitive matching you can create special type of string index.
 *      - $elemMatch The $elemMatch operator matches more than one component within an array element.
 *          -    { array: { $elemMatch: { value1 : 1, value2 : { $gt: 1 } } } }
 *          Restriction: only one $elemMatch allowed in context of one array field.
 *
 *  - Queries can be used to update records:
 *
 *      $set Field set operation.
 *          - {.., '$set' : {'field1' : val1, 'fieldN' : valN}}
 *      $inc Increment operation. Only number types are supported.
 *          - {.., '$inc' : {'field1' : number, ...,  'field1' : number}
 *      $dropall In-place record removal operation.
 *          - {.., '$dropall' : true}
 *      $addToSet Atomically adds value to the array only if its not in the array already.
 *                  If containing array is missing it will be created.
 *          - {.., '$addToSet' : {'json.field.path' : val1, 'json.field.pathN' : valN, ...}}
 *      $pull Atomically removes all occurrences of value from field, if field is an array.
 *          - {.., '$pull' : {'json.field.path' : val1, 'json.field.pathN' : valN, ...}}
 *
 *
 *  NOTE: It is better to execute update queries with `$onlycount=true` hint flag
 *        or use the special `update()` method to avoid unnecessarily data fetching.
 *  NOTE: Negate operations: $not and $nin not using indexes
 *        so they can be slow in comparison to other matching operations.
 *  NOTE: Only one index can be used in search query operation.
 *  NOTE: If callback is not provided this function will be synchronous.
 *
 *  QUERY HINTS (specified by `hints` argument):
 *      - $max Maximum number in the result set
 *      - $skip Number of skipped results in the result set
 *      - $orderby Sorting order of query fields.
 *      - $onlycount true|false If `true` only count of matching records will be returned
 *                              without placing records in result set.
 *      - $fields Set subset of fetched fields
 *          Example:
 *          hints:    {
 *                      "$orderby" : { //ORDER BY field1 ASC, field2 DESC
 *                          "field1" : 1,
 *                          "field2" : -1
 *                      },
 *                      "$fields" : { //SELECT ONLY {_id, field1, field2}
 *                          "field1" : 1,
 *                          "field2" : 1
 *                      }
 *                    }
 *
 * Many C API query examples can be found in `tcejdb/testejdb/t2.c` test case.
 *
 * To traverse selected records cursor object is used:
 *      - Cursor#next() Move cursor to the next record and returns true if next record exists.
 *      - Cursor#hasNext() Returns true if cursor can be placed to the next record.
 *      - Cursor#field(name) Retrieve value of the specified field of the current JSON object record.
 *      - Cursor#object() Retrieve whole JSON object with all fields.
 *      - Cursor#reset() Reset cursor to its initial state.
 *      - Cursor#length Read-only property: Number of records placed into cursor.
 *      - Cursor#pos Read/Write property: You can set cursor position: 0 <= pos < length
 *      - Cursor#close() Closes cursor and free cursor resources. Cursor cant be used in closed state.
 *
 * Call variations of find():
 *       - find(cname, [cb])
 *       - find(cname, qobj, [cb])
 *       - find(cname, qobj, hints, [cb])
 *       - find(cname, qobj, qobjarr, [cb])
 *       - find(cname, qobj, qobjarr, hints, [cb])
 *
 * @param {String} cname Name of collection
 * @param {Object} qobj Main JSON query object
 * @param {Array} [orarr] Array of additional OR query objects (joined with OR predicate).
 * @param {Object} [hints] JSON object with query hints.
 * @param {Function} [cb] Callback function with arguments: (error, cursor, count) where:
 *          `cursor`: Cursor object to traverse records
 *          `count`:  Total number of selected records.
 * @return If callback is provided returns {undefined}.
 *         If no callback and $onlycount hint is set returns count {Number}.
 *         If no callback and no $onlycount hint returns cursor {Object}.
 *
 */
EJDB.prototype.find = function() {
    //[cname, qobj, orarr, hints, cb]
    var qa = parseQueryArgs(arguments);
    return this._impl.query(qa[0], [qa[1]].concat(qa[2], qa[3]),
            (qa[3]["$onlycount"] ? ejdblib.JBQRYCOUNT : 0),
            qa[4]);
};

/**
 * Same as #find() but retrieves only one matching JSON object.
 * If callback is not provided this function will be synchronous.
 *
 * Call variations of findOne():
 *       - findOne(cname, [cb])
 *       - findOne(cname, qobj, [cb])
 *       - findOne(cname, qobj, hints, [cb])
 *       - findOne(cname, qobj, qobjarr, [cb])
 *       - findOne(cname, qobj, qobjarr, hints, [cb])
 *
 * @param {String} cname Name of collection
 * @param {Object} qobj Main JSON query object
 * @param {Array} [orarr] Array of additional OR query objects (joined with OR predicate).
 * @param {Object} [hints] JSON object with query hints.
 * @param {Function} [cb] Callback function with arguments: (error, obj) where:
 *          `obj`:  Retrieved JSON object or NULL if it is not found.
 * @return  If callback is provided returns {undefined}.
 *          If no callback is provided returns found {Object} or {null}.
 */

EJDB.prototype.findOne = function() {
    //[cname, qobj, orarr, hints, cb]
    var qa = parseQueryArgs(arguments);
    qa[3]["$max"] = 1;
    var cb = qa[4];
    if (cb) {
        return this._impl.query(qa[0], [qa[1]].concat(qa[2], qa[3]), 0,
                function(err, cursor) {
                    if (err) {
                        cb(err);
                        return;
                    }
                    if (cursor.next()) {
                        try {
                            cb(null, cursor.object());
                        } finally {
                            cursor.close();
                        }
                    } else {
                        cb(null, null);
                    }
                });
    } else {
        var ret = null;
        var cursor = this._impl.query(qa[0], [qa[1]].concat(qa[2], qa[3]), 0, cb);
        if (cursor && typeof cursor === "object") {
            if (cursor.next()) {
                ret = cursor.object();
            }
            cursor.close();
        }
        return ret;
    }
};


/**
 * Convenient method to execute update queries.
 * If callback is not provided this function will be synchronous.
 *
 * The following update operations are supported:
 *      $set Field set operation.
 *          - {.., '$set' : {'field1' : val1, 'fieldN' : valN}}
 *      $inc Increment operation. Only number types are supported.
 *          - {.., '$inc' : {'field1' : number, ...,  'field1' : number}
 *      $dropall In-place record removal operation.
 *          - {.., '$dropall' : true}
 *      $addToSet Atomically adds value to the array only if its not in the array already.
 *                  If containing array is missing it will be created.
 *          - {.., '$addToSet' : {'json.field.path' : val1, 'json.field.pathN' : valN, ...}}
 *      $pull Atomically removes all occurrences of value from field, if field is an array.
 *          - {.., '$pull' : {'json.field.path' : val1, 'json.field.pathN' : valN, ...}}
 *
 * Call variations of update():
 *    update(cname, qobj, [cb])
 *    update(cname, qobj, hints, [cb])
 *    update(cname, qobj, qobjarr, [cb])
 *    update(cname, qobj, qobjarr, hints, [cb])
 *
 * @param {String} cname Name of collection
 * @param {Object} qobj Main JSON query object
 * @param {Array} [orarr] Array of additional OR query objects (joined with OR predicate).
 * @param {Object} [hints] JSON object with query hints.
 * @param {Function} [cb] Callback function with arguments: (error, count) where:
 *          `count`:  The number of updated records.
 *
 * @return  If callback is provided returns {undefined}.
 *          If no callback is provided returns {Number} of updated objects.
 */
EJDB.prototype.update = function() {
    //[cname, qobj, orarr, hints, cb]
    var qa = parseQueryArgs(arguments);
    var cb = qa[4];
    if (cb) {
        return this._impl.query(qa[0], [qa[1]].concat(qa[2], qa[3]), ejdblib.JBQRYCOUNT,
                function(err, cursor, count, log) {
                    if (err) {
                        cb(err, null, log);
                        return;
                    }
                    cb(null, count, log);
                });
    } else {
        return this._impl.query(qa[0], [qa[1]].concat(qa[2], qa[3]), ejdblib.JBQRYCOUNT, cb);
    }
};

/**
 * Convenient count(*) operation.
 *
 * Call variations of count():
 *       - count(cname, [cb])
 *       - count(cname, qobj, [cb])
 *       - count(cname, qobj, hints, [cb])
 *       - count(cname, qobj, qobjarr, [cb])
 *       - count(cname, qobj, qobjarr, hints, [cb])
 *
 * @param {String} cname Name of collection
 * @param {Object} qobj Main JSON query object
 * @param {Array} [orarr] Array of additional OR query objects (joined with OR predicate).
 * @param {Object} [hints] JSON object with query hints.
 * @param {Function} [cb] Callback function with arguments: (error, count) where:
 *          `count`:  Number of matching records.
 *
 * @return  If callback is provided returns {undefined}.
 *          If no callback is provided returns {Number} of matched object.
 */
EJDB.prototype.count = function() {
    //[cname, qobj, orarr, hints, cb]
    var qa = parseQueryArgs(arguments);
    var cb = qa[4];
    if (cb) {
        return this._impl.query(qa[0], [qa[1]].concat(qa[2], qa[3]), ejdblib.JBQRYCOUNT,
                function(err, cursor, count, log) {
                    if (err) {
                        cb(err, null, log);
                        return;
                    }
                    cb(null, count, log);
                });
    } else {
        return this._impl.query(qa[0], [qa[1]].concat(qa[2], qa[3]), ejdblib.JBQRYCOUNT, cb);
    }
};

/**
 * Synchronize entire EJDB database and
 * all its collections with storage.
 * If callback is not provided this function will be synchronous.
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.sync = function(cb) {
    return this._impl.sync(cb);
};

/**
 * DROP indexes of all types for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.dropIndexes = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXDROPALL, cb);
};

/**
 * OPTIMIZE indexes of all types for JSON field path.
 *  Performs B+ tree index file optimization.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.optimizeIndexes = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXOP, cb);
};

/**
 * Ensure index presence of String type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.ensureStringIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXSTR, cb);
};

/**
 * Rebuild index of String type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.rebuildStringIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXSTR | ejdblib.JBIDXREBLD, cb);
};

/**
 * Drop index of String type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.dropStringIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXSTR | ejdblib.JBIDXDROP, cb);
};

/**
 * Ensure case insensitive String index for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.ensureIStringIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXISTR, cb);
};

/**
 * Rebuild case insensitive String index for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.rebuildIStringIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXISTR | ejdblib.JBIDXREBLD, cb);
};

/**
 * Drop case insensitive String index for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.dropIStringIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXISTR | ejdblib.JBIDXDROP, cb);
};

/**
 * Ensure index presence of Number type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.ensureNumberIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXNUM, cb);
};

/**
 * Rebuild index of Number type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.rebuildNumberIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXNUM | ejdblib.JBIDXREBLD, cb);
};

/**
 * Drop index of Number type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.dropNumberIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXNUM | ejdblib.JBIDXDROP, cb);
};

/**
 * Ensure index presence of Array type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.ensureArrayIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXARR, cb);
};

/**
 * Rebuild index of Array type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.rebuildArrayIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXARR | ejdblib.JBIDXREBLD, cb);
};

/**
 * Drop index of Array type for JSON field path.
 * If callback is not provided this function will be synchronous.
 * @param {String} cname Name of collection
 * @param {String} path  JSON field path
 * @param {Function} [cb] Optional callback function. Callback args: (error)
 */
EJDB.prototype.dropArrayIndex = function(cname, path, cb) {
    return this._impl.setIndex(cname, path, ejdblib.JBIDXARR | ejdblib.JBIDXDROP, cb);
};


/**
 * Get description of EJDB database and its collections.
 */
EJDB.prototype.getDBMeta = function() {
    return this._impl.dbMeta();
};

module.exports = EJDB;