doubledb

An on disk database that indexes everything for fast querying.

Installation

npm install --save doubledb

Features

• read
• insert
• replace
• patch
• remove
• find
• filter
• query

Usage

import createDoubledb from 'doubledb';
const doubledb = createDoubledb('./data');

doubledb.insert({
  id: undefined, // defaults to uuid, must be unique
  firstName: 'Joe',
  lastName: 'Bloggs',
  stats: {
    wins: 10,
    loses: 5
  },
  skills: ['cooking', 'running']
});

doubledb.get(record.id);
doubledb.find('firstName', 'Joe');
doubledb.find('stats.wins', 10);
doubledb.find('skills', 'cooking');
doubledb.find('firstName', v => v.startsWith('J'), { skip: 20, gt: 'J', lt: 'K' });
doubledb.filter('firstName', 'Joe');
doubledb.filter('firstName', v => v.startsWith('J'));
doubledb.filter('firstName', v => v.startsWith('J'), { limit: 10, skip: 20, gt: 'J', lt: 'K' });
doubledb.replace(record.id, { firstName: 'Joe', lastName: 'Bloggs' });
doubledb.patch(record.id, { firstName: 'Bob' });
doubledb.remove(record.id);

.get(id)

Get a single record by it's .id property.

If a record is found, the whole record will be returned. If no record is found, undefined will be returned.

.find(field, value, { skip })

Quickly find a single record by any field (use.dot.notation.for.nested.properties) and it's exact value.

If multiple records exist, a skip option can be provided to ignore the first number of finds.

If a record is found, the whole record will be returned. If no record is found, undefined will be returned.

.find(field, matcherFunction: (value: string) => boolean), { limit, skip, gt, lt, gte, lte })

Slow find a single record by any field and test against a matcherFunction.

If multiple records exist:

• a skip option can be provided to ignore the first number of finds.
• a limit option can be provided to stop after number of finds.

Find using a matcherFunction will work without a gt and lt, but the indexing will be pretty useless, as it will need to scan every single record.

You should provide a gt and/or lt to let the indexer know where to begin/end.

For example, the query below will scan every first name from A all the way to Z

doubledb.find('firstName', v => v.startsWith('Jo'))

Let's tell it to start from Jo.

doubledb.find('firstName', v => v.startsWith('Jo'), { gt: 'Jo' })

This will skip all indexes lower than Jo. However if it can't find any records, it will keep checking, even if the firstName is Zelda

So we should help the indexer by giving it a lt.

doubledb.find('firstName', v => v.startsWith('Jo'), { gt: 'Jo', lt: 'K' })

Let's look at some more examples:

doubledb.find('favouriteNumber', v => v > 5 && v < 10, { gt: 5, lt: 10 })
doubledb.find('firstName', v => ['Dave', 'Peter'].includes(v), { gt: 'Dave', lte: 'Peter' })

If a record is found, the whole record will be returned. If no record is found, undefined will be returned.

.filter(field, matcherFunction: (value: string) => boolean), { limit, skip, gt, lt, gte, lte })

This works the exact same as .find but will return an array.

If records are found, an array will be returned containing every complete found record. If no records are found, an empty array will be returned.

.replace(key, object)

Completely replace a key with a new object, losing all previous fields in the record.

.patch(key, object)

Merge the new object in with the existing record.

For example, if the following record exists:

{
  "id": "1",
  "firstName": "Joe",
  "lastName": "Bloggs"
}

And you run the following .patch.

doubledb.patch('1', { fullName: 'Joe Bloggs' })

The final record will be:

{
  "id": "1",
  "firstName": "Joe",
  "lastName": "Bloggs",
  "fullName": "Joe Bloggs"
}

.remove(key)

Completely remove the key and it's value from the database.

Proposed Query

This hasn't been implemented yet, but it's something I'd like and think could work.

const record = doubledb.query({
  location: 'London',
  category: 'b',

  $or: {
    firstName: {
      $eq: 'Joe',
    },
    firstName: {
      $eq: 'joe',
    }
  }
})