It aims to be a fast MongoDB-like library which can be embedded into C/C++/NodeJS/Python/Lua/Java/Ruby applications under terms of LGPL license.
EJDB is the C library based on modified version of Tokyo Cabinet.
JSON representation of queries and data implemented with API based on C BSON
2013-05-06
Ruby binding available2013-05-02
NodeJS win32 module available2013-04-25
EJDB and TokyoCabinet API ported to Windows2013-04-03
Java API binding available2013-03-20
Lua binding available2013-02-15
EJDB Python3 binding available2013-02-07
Debian packages provided2013-01-22
Collection joins now supported
- LGPL license allows you to embed this library into proprietary software.
- EJDB and TokyoCabinet API ported to Windows
- MongoDB-like queries and overall philosophy.
- Collection level write locking.
- Collection level transactions.
- String token matching queries:
$stror
$strand
- Node.js binding
- Collection joins
- Python/Lua/Java/Ruby bindings
- EJDB Command line interface
- NodeJS binding
- Python3 binding
- Lua binding
- Java binding
- Ruby binding
- EJDB C Library
- Collection joins
- We use EJDB Google group as our mailing list.
- Projects using EJDB
var EJDB = require("ejdb");
//Open zoo DB
var jb = EJDB.open("zoo", EJDB.DEFAULT_OPEN_MODE | EJDB.JBOTRUNC);
var parrot1 = {
"name" : "Grenny",
"type" : "African Grey",
"male" : true,
"age" : 1,
"birthdate" : new Date(),
"likes" : ["green color", "night", "toys"],
"extra1" : null
};
var parrot2 = {
"name" : "Bounty",
"type" : "Cockatoo",
"male" : false,
"age" : 15,
"birthdate" : new Date(),
"likes" : ["sugar cane"]
};
jb.save("parrots", [parrot1, parrot2], function(err, oids) {
if (err) {
console.error(err);
return;
}
console.log("Grenny OID: " + parrot1["_id"]);
console.log("Bounty OID: " + parrot2["_id"]);
jb.find("parrots",
{"likes" : "toys"},
{"$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
});
});
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 on linux/macos:
npm install ejdb
Installing EJDB NodeJS module on windows
### 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, <json object>|<Array of json objects>, [options] [cb])
save(cname, <json object>|<Array of json objects>, [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 qobjcount
: 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)
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()
local ejdb = require("ejdb")
local inspect = require("ejdb.inspect")
local Q = ejdb.Q
-- Used modes:
-- 'r' - read
-- 'w' - write
-- 'c' - create db if not exists
-- 't' - truncate existing db
local db = ejdb.open("zoo", "rwct")
-- Unordered lua table
local parrot1 = {
name = "Grenny",
type = "African Grey",
male = true,
age = 1,
birthhdate = ejdb.toDateNow(),
likes = { "green color", "night", "toys" },
extra1 = ejdb.toNull()
}
-- Preserve order of BSON keys
local parrot2 = Q();
parrot2:KV("name", "Bounty"):KV("type", "Cockatoo"):KV("male", false)
parrot2:KV("age", 15):KV("birthdate",
ejdb.toDate({ year = 2013, month = 1, day = 1, hour = 0, sec = 1 }))
parrot2:KV("likes", { "sugar cane" }):KV("extra1", ejdb.toNull())
--IF YOU WANT SOME DATA INSPECTIONS:
--print(ejdb.print_bson(parrot2:toBSON()))
--local obj = ejdb.from_bson(parrot2:toBSON())
--print(inspect(obj));
db:save("parrots2", parrot1)
db:save("parrots2", parrot2)
-- Below two equivalent queries:
-- Q1
local res, count, log =
db:find("parrots2", Q("likes", "toys"):OrderBy("name asc", "age desc"))
for i = 1, #res do -- iterate one
local ob = res:object(i)
print("" .. ob["name"] .. " likes toys #1")
end
-- Q2
local res, count, log =
db:find("parrots2", Q():F("likes"):Eq("toys"):OrderBy({ name = 1 }, { age = -1 }))
for i = 1, #res do -- iterate one
print("" .. res:field(i, "name") .. " likes toys #2")
end
-- Second way to iterate
for vobj, idx in res() do
print("" .. vobj["name"] .. " likes toys #3")
end
db:close()
#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 = 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(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:
gcc -std=c99 -Wall -pedantic -c -o csnippet.o csnippet.c
gcc -o csnippet csnippet.o -ltcejdb
System libraries:
- gcc
- zlib-dev
cd ./tcejdb
./configure --prefix=<installation prefix> && make && make check
make install
- library name: tcejdb (with pkgconfig)
- main include header:
<tcejdb/ejdb.h>
EJDB API presented in ejdb.h C header file.
JSON processing API: bson.h
/**
* 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);
You can find some code samples in:
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
- One ejdb database can handle up to 1024 collections.
- Indexes for objects in nested arrays currently not supported (#37)
- Collect collection index statistic