CRBL is a line by line "database" without Updates and Deletes, hence the name:
C(CREATE)R(READ)BL(By Line)
What means line by line - it means each item stored in database as single line of file.
As we starting from scratch, lets create and connect to database from code:
const { CRBL } = require('crbl')
const db = await CRBL.createAndConnect('/path/to/db', {
fileCapacity: 10, // files in store will contain max 10 lines.
fileExtension: 'ext' // newly created files will have extension .txt
})Note: We assume that we can use top level await. In node environment you need to create async function to execute presented examples.
Lets continue and insert items to it and query them:
// 4 synchronous calls of Insert Async operation will executed in same order,
// as if they were synchronous.
db.insert().one('1').then()
db.insert().many(['2','3']).then()
db.insert('4').then()
await db.insert(['5','6'])
const result = await db.query()
console.log(result)
// will be printed:
// {
// queryItems: [
// { id: 0, item: '1' },
// { id: 1, item: '2' },
// { id: 2, item: '3' },
// { id: 3, item: '4' },
// { id: 4, item: '5' },
// { id: 5, item: '6' }
// ],
// lCount: 6,
// fCount: 1
// }Insert operations above will be executed in same order they called. This is for case when multiple write operations performed agains single file. To avoid mixing lines, we take this solution.
In the example above, first will be performed all insertes, and when final insert operation is finish, database will be queried for all lines.
You can also query concrete files in database store:
await db.insert().many(['7','8','9','10','11','12','13'])
const result = await db.query().segment(0) // query first(0 based index) file in
console.log(result)
// will be printed:
// {
// queryItems: [
// { id: 0, item: '1' },
// { id: 1, item: '2' },
// { id: 2, item: '3' },
// { id: 3, item: '4' },
// { id: 4, item: '5' },
// { id: 5, item: '6' },
// { id: 6, item: '7' },
// { id: 7, item: '8' },
// { id: 8, item: '9' },
// { id: 9, item: '10' }
// ],
// lCount: 13,
// fCount: 2
// }Or ranges of files:
const result = await db.query().segmentRange([0, 1]) // query first two files in database
console.log(result)
// will be printed:
// {
// queryItems: [
// { id: 0, item: '1' },
// { id: 1, item: '2' },
// { id: 2, item: '3' },
// { id: 3, item: '4' },
// { id: 4, item: '5' },
// { id: 5, item: '6' },
// { id: 6, item: '7' },
// { id: 7, item: '8' },
// { id: 8, item: '9' },
// { id: 9, item: '10' },
// { id: 10, item: '11' },
// { id: 11, item: '12' },
// { id: 12, item: '13' }
// ],
// lCount: 13,
// fCount: 2
// }You can also skip some lines and limit the result.
const result = await db.query().skip(4).limit(7) // query 7 items after 4-th line.
console.log(result)
// will be printed:
// {
// queryItems: [
// { id: 4, item: '5' },
// { id: 5, item: '6' },
// { id: 6, item: '7' },
// { id: 7, item: '8' },
// { id: 8, item: '9' },
// { id: 9, item: '10' },
// { id: 10, item: '11' }
// ],
// lCount: 13,
// fCount: 2
// }Note: Order of .skip() and .limit() calls not matter, firs will be performed skip operation and then limit.
You can also performe search operations with find method:
const result = await db.query()
.skip(4)
.limit(7)
.find(line => line === '5' || line === '10') // query 7 items after 4-th line.
console.log(result)
// will be printed:
// {
// queryItems: [ { id: 4, item: '5' }, { id: 9, item: '10' } ],
// lCount: 13,
// fCount: 2
// }
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