4.5 KiB
| 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.
:::
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:
{
"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.
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:
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.
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.
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.
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.
if(type == "hash") {
let values = await client.HGETALL(key);
aoa = [ ["Hash"], [key] ].concat(Object.entries(values));
}
Example
Complete Example (click to show)
-
Set up and start a local Redis server
-
Download the following scripts:
- Install dependencies and run:
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