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[![EJDB](https://raw.github.com/Softmotions/ejdb/master/misc/ejdblogo3.png)](http://ejdb.org)


Embedded JSON Database engine
====================================

It aims to be a fast [MongoDB](http://mongodb.org)-like library **which can be embedded into C/C++ and [NodeJS](http://nodejs.org/) applications under terms of LGPL license.**

EJDB is the C library based on modified version of [Tokyo Cabinet](http://fallabs.com/tokyocabinet/).

JSON representation of queries and data implemented with API based on [C BSON](https://github.com/mongodb/mongo-c-driver/tree/master/src/)

Features
================================
* LGPL license allows you to embed this library into proprietary software.
* MongoDB-like queries and overall philosophy.
* Collection level write locking.
* Collection level transactions.
* String token matching queries: ```$stror``` ```$strand```
* [Node.js](http://nodejs.org) binding


Documentation
================================

* **[EJDB Command line interface](https://github.com/Softmotions/ejdb/wiki/EJDB-Command-line-interface)**
* **[NodeJS binding](#nodejs-binding)**
    * [Installation](#installation)
    * [Samples](#ejdb-nodejs-samples)
    * [NodeJS API](#ejdb-nodejs-api)
* **[EJDB C Library](#ejdb-c-library)**
    * [Building & Installation](#building--installation)
    * [Samples](#ejdb-c-samples)
    * [C API](#c-api)

Community
================================
We use [EJDB Google group](http://groups.google.com/group/ejdb) as our mailing list.

EJDB C Library
==================================

One snippet intro
-----------------------------------

~~~~~~
#include <tcejdb/ejdb.h>

static EJDB *jb;

int main() {
    jb = ejdbnew();
    if (!ejdbopen(jb, "addressbook", JBOWRITER | JBOCREAT | JBOTRUNC)) {
        return 1;
    }
    //Get or create collection 'contacts'
    EJCOLL *coll = ejdbcreatecoll(jb, "contacts", NULL);

    bson bsrec;
    bson_oid_t oid;

    //Insert one record:
    //JSON: {'name' : 'Bruce', 'phone' : '333-222-333', 'age' : 58}
    bson_init(&bsrec);
    bson_append_string(&bsrec, "name", "Bruce");
    bson_append_string(&bsrec, "phone", "333-222-333");
    bson_append_int(&bsrec, "age", 58);
    bson_finish(&bsrec);
    //Save BSON
    ejdbsavebson(coll, &bsrec, &oid);
    fprintf(stderr, "\nSaved Bruce");
    bson_destroy(&bsrec);

    //Now execute query
    //QUERY: {'name' : {'$begin' : 'Bru'}} //Name starts with 'Bru' string
    bson bq1;
    bson_init_as_query(&bq1);
    bson_append_start_object(&bq1, "name");
    bson_append_string(&bq1, "$begin", "Bru");
    bson_append_finish_object(&bq1);
    bson_finish(&bq1);

    EJQ *q1 = ejdbcreatequery(jb, &bq1, NULL, 0, NULL);

    uint32_t count;
    TCLIST *res = ejdbqrysearch(coll, q1, &count, 0, NULL);
    fprintf(stderr, "\n\nRecords found: %d\n", count);

    //Now print the result set records
    for (int i = 0; i < TCLISTNUM(res); ++i) {
        void *bsdata = TCLISTVALPTR(res, i);
        bson_print_raw(stderr, bsdata, 0);
    }
    fprintf(stderr, "\n");

    //Dispose result set
    tclistdel(res);

    //Dispose query
    ejdbquerydel(q1);
    bson_destroy(&bq1);

    //Close database
    ejdbclose(jb);
    ejdbdel(jb);
    return 0;
}
~~~~~~

You can save this code in `csnippet.c` And build:


```sh
gcc -std=c99 -Wall -pedantic  -c -o csnippet.o csnippet.c
gcc -std=c99 -Wall -pedantic  -o csnippet csnippet.o  -ltcejdb
```

Building & Installation
--------------------------------

Prerequisites
--------------------------------
**System libraries:**

* gcc
* zlib

On Debian/Ubuntu linux you can install it as follows:

```sh
   sudo apt-get install gcc zlib1g zlib1g-dev
```

Building
--------------------------------

~~~~~~
   cd ./tcejdb
   ./configure --prefix=<installation prefix> && make && make check
   make install
~~~~~~
* library name: **tcejdb** (with pkgconfig)
* main include header: ```<tcejdb/ejdb.h>```

C API
---------------------------------
EJDB API presented in **[ejdb.h](https://github.com/Softmotions/ejdb/blob/master/tcejdb/ejdb.h)** C header file.

JSON processing API: **[bson.h](https://github.com/Softmotions/ejdb/blob/master/tcejdb/bson.h)**

Queries
---------------------------------

~~~~~~
/**
 * Create query object.
 * Sucessfully created queries must be destroyed with ejdbquerydel().
 *
 * EJDB queries inspired by MongoDB (mongodb.org) and follows same philosophy.
 *
 *  - Supported queries:
 *      - Simple matching of String OR Number OR Array value:
 *          -   {'fpath' : 'val', ...}
 *      - $not Negate operation.
 *          -   {'fpath' : {'$not' : val}} //Field not equal to val
 *          -   {'fpath' : {'$not' : {'$begin' : prefix}}} //Field not begins with val
 *      - $begin String starts with prefix
 *          -   {'fpath' : {'$begin' : prefix}}
 *      - $gt, $gte (>, >=) and $lt, $lte for number types:
 *          -   {'fpath' : {'$gt' : number}, ...}
 *      - $bt Between for number types:
 *          -   {'fpath' : {'$bt' : [num1, num2]}}
 *      - $in String OR Number OR Array val matches to value in specified array:
 *          -   {'fpath' : {'$in' : [val1, val2, val3]}}
 *      - $nin - Not IN
 *      - $strand String tokens OR String array val matches all tokens in specified array:
 *          -   {'fpath' : {'$strand' : [val1, val2, val3]}}
 *      - $stror String tokens OR String array val matches any token in specified array:
 *          -   {'fpath' : {'$stror' : [val1, val2, val3]}}
 *      - $exists Field existence matching:
 *          -   {'fpath' : {'$exists' : true|false}}
 *      - $icase Case insensitive string matching:
 *          -    {'fpath' : {'$icase' : 'val1'}} //icase matching
 *          Ignore case matching with '$in' operation:
 *          -    {'name' : {'$icase' : {'$in' : ['tHéâtre - театр', 'heLLo WorlD']}}}
 *          For case insensitive matching you can create special index of type: `JBIDXISTR`
 *     - $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}}
 *       $upsert Atomic upsert. If matching records are found it will be '$set' operation,
 *              otherwise new record will be inserted with fields specified by argment object.
 *           - {.., '$upsert' : {'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' : {'fpath' : val1, 'fpathN' : valN, ...}}
 *       $addToSetAll Batch version if $addToSet
 *           - {.., '$addToSetAll' : {'fpath' : [array of values to add], ...}}
 *       $pull Atomically removes all occurrences of value from field, if field is an array.
 *           - {.., '$pull' : {'fpath' : val1, 'fpathN' : valN, ...}}
 *       $pullAll Batch version of $pull
 *           - {.., '$pullAll' : {'fpath' : [array of values to remove], ...}}
 *
 *  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.
 *
 *  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.
 *      - $fields Set subset of fetched fields
            If a field presented in $orderby clause it will be forced to include in resulting records.
 *          Example:
 *          hints:    {
 *                      "$orderby" : { //ORDER BY field1 ASC, field2 DESC
 *                          "field1" : 1,
 *                          "field2" : -1
 *                      },
 *                      "$fields" : { //SELECT ONLY {_id, field1, field2}
 *                          "field1" : 1,
 *                          "field2" : 1
 *                      }
 *                    }
 *
 * Many query examples can be found in `testejdb/t2.c` test case.
 *
 * @param EJDB database handle.
 * @param qobj Main BSON query object.
 * @param orqobjs Array of additional OR query objects (joined with OR predicate).
 * @param orqobjsnum Number of OR query objects.
 * @param hints BSON object with query hints.
 * @return On success return query handle. On error returns NULL.
 */
EJDB_EXPORT EJQ* ejdbcreatequery(EJDB *jb, bson *qobj, bson *orqobjs, int orqobjsnum, bson *hints);
~~~~~~

EJDB C Samples
------------------------------------
You can find some code samples in:

* [tcejdb/samples](https://github.com/Softmotions/ejdb/tree/master/tcejdb/samples)
* [tcejdb/testejdb](https://github.com/Softmotions/ejdb/tree/master/tcejdb/testejdb)

Basic EJDB architecture
------------------------------------
**EJDB database files structure**

~~~~~~
.
├── <dbname>
├── <dbname>_<collection1>
├── ...
├── <dbname>_<collectionN>
└── <dbname>_<collectionN>_<fieldpath>.<index ext>
~~~~~~

Where

* ```<dbname>``` - name of database. It is metadata DB.
* ```<collectionN>``` - name of collection. Collection database.
* ```<fieldpath>``` - JSON field path used in index
* ```<index ext>``` - Collection index extension:
    * ```.lex``` String index
    * ```.dec``` Number index
    * ```.tok``` Array index

Limitations
------------------------------------
* One ejdb database can handle up to 1024 collections.
* Indexes for objects in nested arrays currently not supported (#37)

TODO
------------------------------------
* Collect collection index statistic
* Windows port

Related software
------------------------------------
[Connect session store backed by EJDB database](https://github.com/Softmotions/connect-session-ejdb)