[![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/) News =============================== * `2013-02-15` **[EJDB Python3 binding available](https://github.com/Softmotions/ejdb/blob/master/pyejdb/README.md)** * `2013-02-07` **[Debian packages provided](https://github.com/Softmotions/ejdb/wiki/Debian-Ubuntu-installation)** * `2013-01-22` **[Collection joins now supported](https://github.com/Softmotions/ejdb/wiki/Collection-joins)** 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 * [Collection joins](https://github.com/Softmotions/ejdb/wiki/Collection-joins) 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) * **[Python3 binding](#ejdb-python3-binding)** * **[EJDB C Library](#ejdb-c-library)** * [Building & Installation](#building--installation) * [Samples](#ejdb-c-samples) * [C API](#c-api) * **[Collection joins](https://github.com/Softmotions/ejdb/wiki/Collection-joins)** Community ================================ We use [EJDB Google group](http://groups.google.com/group/ejdb) as our mailing list. NodeJS binding ================================= One snippet intro --------------------------------- ```JavaScript var EJDB = require("ejdb"); //Open zoo DB var jb = EJDB.open("zoo", EJDB.DEFAULT_OPEN_MODE | EJDB.JBOTRUNC); var parrot1 = { "name" : "Grenny", "type" : "African Grey", "male" : true, "age" : 1, "birthdate" : new Date(), "likes" : ["green color", "night", "toys"], "extra1" : null }; var parrot2 = { "name" : "Bounty", "type" : "Cockatoo", "male" : false, "age" : 15, "birthdate" : new Date(), "likes" : ["sugar cane"] }; jb.save("parrots", [parrot1, parrot2], function(err, oids) { if (err) { console.error(err); return; } console.log("Grenny OID: " + parrot1["_id"]); console.log("Bounty OID: " + parrot2["_id"]); jb.find("parrots", {"likes" : "toys"}, {"$orderby" : {"name" : 1}}, function(err, cursor, count) { if (err) { console.error(err); return; } console.log("Found " + count + " parrots"); while (cursor.next()) { console.log(cursor.field("name") + " likes toys!"); } cursor.close(); //It's not mandatory to close cursor explicitly jb.close(); //Close the database }); }); ``` Installation -------------------------------- **System libraries:** * g++ * zlib On Debian/Ubuntu linux you can install it as follows: ~~~~~~ sudo apt-get install g++ zlib1g zlib1g-dev ~~~~~~ **Installation from node package manager:** npm install ejdb EJDB NodeJS samples --------------------------------- * [node/samples](https://github.com/Softmotions/ejdb/tree/master/node/samples) * [node/tests](https://github.com/Softmotions/ejdb/tree/master/node/tests) * [nwk-ejdb-address-book](https://github.com/Softmotions/nwk-ejdb-address-book) EJDB NodeJS API ---------------------------------- ### EJDB.open(dbFile, openMode) Open database. Return database instance handle object.
Default open mode: `JBOWRITER | JBOCREAT`.
This is blocking function. __Arguments__ * {String} dbFile Database main file name * {Number} `[openMode=JBOWRITER | JBOCREAT]` Bitmast of open modes: - `JBOREADER` Open as a reader. - `JBOWRITER` Open as a writer. - `JBOCREAT` Create if db file not exists - `JBOTRUNC` Truncate db. --------------------------------------- ### close() Close database.
If database was not opened it does nothing.
This is blocking function. --------------------------------------- ### isOpen() Check if database in opened state. --------------------------------------- ### ensureCollection(cname, copts) Automatically creates new collection if it does't exists. Collection options `copts` 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 * compressed : If true collection records will be compressed with DEFLATE compression. Default: false.
This is blocking function. __Arguments__ * {String} cname Name of collection. * {Object} `[copts]` Collection options. --------------------------------------- ### dropCollection(cname, prune, cb) Drop collection. Call variations: dropCollection(cname) dropCollection(cname, cb) dropCollection(cname, prune, cb) __Arguments__ * {String} cname Name of collection. * {Boolean} `[prune=false]` If true the collection data will erased from disk. * {Function} `[cb]` Callback args: (error) --------------------------------------- ### save(cname, jsarr, 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, |, [options] [cb]) save(cname, |, [cb]) NOTE: Field names of passed JSON objects may not contain `$` and `.` characters, error condition will be fired in this case. __Arguments__ * {String} **cname** Name of collection. * {Array|Object} jsarr Signle JSON object or array of JSON objects to save * {Function} `[cb]` Callback args: (error, {Array} of OIDs for saved objects) __Return__ * {Array} of OIDs of saved objects in synchronous mode otherwise returns {undefined}. -------------------------------------- ### load(cname, oid, cb) Loads JSON object identified by OID from the collection. If callback is not provided this function will be synchronous. __Arguments__ * {String} cname Name of collection * {String} oid Object identifier (OID) * {Function} cb Callback args: (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}. -------------------------------------- ### remove(cname, oid, cb) Removes JSON object from the collection. If callback is not provided this function will be synchronous. __Arguments__ * {String} cname Name of collection * {String} oid Object identifier (OID) * {Function} cb Callback args: (error) -------------------------------------- ### find(cname, qobj, orarr, hints, cb) 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: - {'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 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}} $upsert Atomic upsert. If matching records are found it will be '$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: It is better to execute update queries with `$onlycount=true` hint flag or use the special `update()` method to avoid unnecessarily rows 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 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 }, "$fields" : { //SELECT ONLY {_id, field1, field2} "field1" : 1, "field2" : 1 } } Many C API query examples can be found in `tcejdb/testejdb/t2.c` test case. To traverse selected records cursor object is used: - Cursor#next() Move cursor to the next record and returns true if next record exists. - Cursor#hasNext() Returns true if cursor can be placed to the next record. - Cursor#field(name) Retrieve value of the specified field of the current JSON object record. - Cursor#object() Retrieve whole JSON object with all fields. - Cursor#reset() Reset cursor to its initial state. - Cursor#length Read-only property: Number of records placed into cursor. - Cursor#pos Read/Write property: You can set cursor position: 0 <= pos < length - Cursor#close() Closes cursor and free cursor resources. Cursor cant be used in closed state. Call variations of find(): - find(cname, [cb]) - find(cname, qobj, [cb]) - find(cname, qobj, hints, [cb]) - find(cname, qobj, qobjarr, [cb]) - find(cname, qobj, qobjarr, hints, [cb]) __Arguments__ * {String} cname Name of collection * {Object} qobj Main JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, cursor, count) `cursor`: Cursor object to traverse records qobj `count`: Total number of selected records __Return__ * If callback is provided returns {undefined} * If no callback and `$onlycount` hint is set returns count {Number}. * If no callback and no `$onlycount` hint returns cursor {Object}. -------------------------------------------- ### findOne(cname, qobj, orarr, hints, cb) Same as #find() but retrieves only one matching JSON object. Call variations of findOne(): findOne(cname, [cb]) findOne(cname, qobj, [cb]) findOne(cname, qobj, hints, [cb]) findOne(cname, qobj, qobjarr, [cb]) findOne(cname, qobj, qobjarr, hints, [cb]) __Arguments__ * {String} cname Name of collection * {Object} qobj Main JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, obj) `obj` Retrieved JSON object or NULL if it is not found. __Return__ * If callback is provided returns {undefined} * If no callback is provided returns found {Object} or {null} ----------------------------------- ### update(cname, qobj, orarr, hints, cb) Convenient method to execute update queries. * `$set` Field set operation: - {some fields for selection, '$set' : {'field1' : {obj}, ..., 'field1' : {obj}}} * `$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}} * `$inc` Increment operation. Only number types are supported. - {some fields for selection, '$inc' : {'field1' : number, ..., 'field1' : {number}} * `$dropall` In-place record removal operation. - {some fields for selection, '$dropall' : true} * `$addToSet` | `$addToSetAll` Atomically adds value to the array only if its not in the array already. If containing array is missing it will be created. - {.., '$addToSet' : {'fpath' : val1, 'fpathN' : valN, ...}} * `$pull` | `pullAll` Atomically removes all occurrences of value from field, if field is an array. - {.., '$pull' : {'fpath' : val1, 'fpathN' : valN, ...}} Call variations of update(): update(cname, [cb]) update(cname, qobj, [cb]) update(cname, qobj, hints, [cb]) update(cname, qobj, qobjarr, [cb]) update(cname, qobj, qobjarr, hints, [cb]) __Arguments__ * {String} cname Name of collection * {Object} qobj Update JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, count) `count` The number of updated records. __Return__ * If callback is provided returns {undefined}. * If no callback is provided returns {Number} of updated objects. ----------------------------------- ### count(cname, qobj, orarr, hints, 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]) __Arguments__ * {String} cname Name of collection * {Object} qobj Main JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, count) `count`: Number of matching records. __Return__ * If callback is provided returns {undefined}. * If no callback is provided returns {Number} of matched object. ----------------------------------- ### sync(cb) Synchronize entire EJDB database with disk. __Arguments__ * {Function} cb Callback args: (error) ----------------------------------- ### dropIndexes(cname, path, cb) Drop indexes of all types for JSON field path. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ------------------------------------ ### optimizeIndexes(cname, path, cb) Optimize indexes of all types for JSON field path. Performs B+ tree index file optimization. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ----------------------------------- ### ensureStringIndex(cname, path, cb) ### ensureIStringIndex(cname, path, cb) ### ensureNumberIndex(cname, path, cb) ### ensureArrayIndex(cname, path, cb) Ensure index presence of String|Number|Array type for JSON field path. `IString` is the special type of String index for case insensitive matching. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ----------------------------------- ### rebuildStringIndex(cname, path, cb) ### rebuildIStringIndex(cname, path, cb) ### rebuildNumberIndex(cname, path, cb) ### rebuildArrayIndex(cname, path, cb) Rebuild index of String|Number|Array type for JSON field path. `IString` is the special type of String index for case insensitive matching. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ----------------------------------- ### dropStringIndex(cname, path, cb) ### dropIStringIndex(cname, path, cb) ### dropNumberIndex(cname, path, cb) ### dropArrayIndex(cname, path, cb) Drop index of String|Number|Array type for JSON field path. `IString` is the special type of String index for case insensitive matching. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ----------------------------------- EJDB Python3 binding ================================== One snippet intro --------------------------------- ```python import pyejdb from datetime import datetime #Open database ejdb = pyejdb.EJDB("zoo", pyejdb.DEFAULT_OPEN_MODE | pyejdb.JBOTRUNC) parrot1 = { "name": "Grenny", "type": "African Grey", "male": True, "age": 1, "birthdate": datetime.utcnow(), "likes": ["green color", "night", "toys"], "extra1": None } parrot2 = { "name": "Bounty", "type": "Cockatoo", "male": False, "age": 15, "birthdate": datetime.utcnow(), "likes": ["sugar cane"], "extra1": None } ejdb.save("parrots2", parrot1, parrot2) with ejdb.find("parrots2", {"likes" : "toys"}, hints={"$orderby" : [("name", 1)]}) as cur: print("found %s parrots" % len(cur)) for p in cur: print("%s likes toys!" % p["name"]) ejdb.close() ``` [EJDB Python3 binding page](https://github.com/Softmotions/ejdb/blob/master/pyejdb/README.md) EJDB C Library ================================== One snippet intro ----------------------------------- ~~~~~~ #include 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 = ejdbqryexecute(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 -o csnippet csnippet.o -ltcejdb ``` Building & Installation -------------------------------- [Installing on Debian/Ubuntu](https://github.com/Softmotions/ejdb/wiki/Debian-Ubuntu-installation) Manual installation ------------------------------- ### Prerequisites **System libraries:** * gcc * zlib-dev ### Build and install ~~~~~~ cd ./tcejdb ./configure --prefix= && make && make check make install ~~~~~~ * library name: **tcejdb** (with pkgconfig) * main include header: `````` 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** ~~~~~~ . ├── ├── _ ├── ... ├── _ └── __. ~~~~~~ Where * `````` - name of database. It is metadata DB. * `````` - name of collection. Collection database. * `````` - JSON field path used in index * `````` - 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)