--- title: NoSQL Data Stores --- import Tabs from '@theme/Tabs'; import TabItem from '@theme/TabItem'; So-called "Schema-less" databases allow for arbitrary keys and values within the entries in the database. K/V stores and Objects add additional restrictions. :::note These data stores are capable of storing structured data. Those use cases are covered in the [Database demo](./database). ::: ## Arbitrary Data to Spreadsheets There is no natural way to translate arbitrarily shaped schemas to worksheets in a workbook. One common trick is to dedicate one worksheet to holding named keys. For example, considering the JS object: ```json { "title": "SheetDB", "metadata": { "author": "SheetJS", "code": 7262 }, "data": [ { "Name": "Barack Obama", "Index": 44 }, { "Name": "Donald Trump", "Index": 45 }, ] } ``` A dedicated worksheet should store the one-off named values: ``` XXX| A | B | ---+-----------------+---------+ 1 | Path | Value | 2 | title | SheetDB | 3 | metadata.author | SheetJS | 4 | metadata.code | 7262 | ``` ## Data Stores ### Redis Redis has 5 core data types: "String", List", "Set", "Sorted Set", and "Hash". Since the keys and values are limited to simple strings (and numbers), it is possible to store complete databases in a single worksheet. ![SheetJSRedis.xlsx](pathname:///nosql/sheetjsredis.png) #### Mapping The first row holds the data type and the second row holds the property name. Strings can be stored in a unified String table. The first column holds keys and the second column holds values: ``` XXX| A | B | ---+---------+-------+ 1 | Strings | | 2 | | | 3 | Hello | World | 4 | Sheet | JS | ``` The SheetJS array-of-arrays representation of the string table is an array of key/value pairs: ```js let aoa = ["Strings"]; aoa.length = 2; // [ "Strings", empty ] const keys = await client.KEYS("*"); for(let key of keys) { const type = await client.TYPE(key); if(type == "string") aoa.push([key, await client.GET(key)]); } ``` Lists are unidimensional and can be stored in their own columns. ``` XXX| C | ---+---------+ 1 | List | 2 | List1 | 3 | List1V1 | 4 | List1V2 | ``` The SheetJS array-of-arrays representation of lists is a column of values. ```js if(type == "list") { let values = await client.LRANGE(key, 0, -1); aoa = [ ["List"], [key] ].concat(values.map(v => [v])); } ``` Sets are unidimensional and can be stored in their own columns. ``` XXX| D | ---+-------+ 1 | Set | 2 | Set1 | 3 | Set1A | 4 | Set1B | ``` The SheetJS array-of-arrays representation of sets is a column of values. ```js if(type == "set") { let values = await client.SMEMBERS(key); aoa = [ ["Set"], [key] ].concat(values.map(v => [v])); } ``` Sorted Sets have an associated score which can be stored in the second column. ``` XXX| E | F | ---+---------+---+ 1 | Sorted | | 2 | ZSet1 | | 3 | Key1 | 1 | 4 | Key2 | 2 | ``` The SheetJS array-of-arrays representation is an array of key/score pairs. ```js if(type == "zset") { let values = await client.ZRANGE_WITHSCORES(key, 0, -1); aoa = [ ["Sorted"], [key] ].concat(values.map(v => [v.value, v.score])); } ``` Hashes are stored like the string table, with key and value columns in order. ``` XXX| G | H | ---+-------+-------+ 1 | Hash | | 2 | Hash1 | | 3 | Key1 | Val1 | 4 | Key2 | Val2 | ``` The SheetJS array-of-arrays representation is an array of key/value pairs. ```js if(type == "hash") { let values = await client.HGETALL(key); aoa = [ ["Hash"], [key] ].concat(Object.entries(values)); } ``` #### Example
Complete Example (click to show) 0) Set up and start a local Redis server 1) Download the following scripts: - [`SheetJSRedis.mjs`](pathname:///nosql/SheetJSRedis.mjs) - [`SheetJSRedisTest.mjs`](pathname:///nosql/SheetJSRedisTest.mjs) 2) Install dependencies and run: ```bash npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz redis node SheetJSRedisTest.mjs ``` Inspect the output and compare with the data in `SheetJSRedisTest.mjs`. Open `SheetJSRedis.xlsx` and verify the columns have the correct data