mirror of
https://github.com/Brandon-Rozek/website.git
synced 2024-11-09 10:40:34 -05:00
New Post
This commit is contained in:
parent
0f2550fbbb
commit
4a0c18652a
1 changed files with 126 additions and 0 deletions
126
content/blog/simple-kv-store-sqlite.md
Normal file
126
content/blog/simple-kv-store-sqlite.md
Normal file
|
@ -0,0 +1,126 @@
|
|||
---
|
||||
title: "Simple Key-Value Store using Sqlite3"
|
||||
date: 2023-11-09T22:15:23-05:00
|
||||
draft: false
|
||||
tags: ["DB"]
|
||||
math: false
|
||||
medium_enabled: false
|
||||
---
|
||||
|
||||
A lot of software nowadays are built for scale. You have to setup a Kubernetes cluster and deploy Redis for duplication in order to have a key-value store. Though for many small projects, I feel like it's overkill.
|
||||
|
||||
I'll show in this post, that we can have a nice simple[^1] key-value store using `sqlite3`. This gives us the benefit that we don't need to use system resources to run a daemon the entire time and only spin up a process when we need it.
|
||||
|
||||
For our key-value store, we're going to use a table with two columns:
|
||||
|
||||
- A key, which we'll call `name`. This will be a unique `TEXT` type that has to be set.
|
||||
- The value, which we'll call `value` (Creative, I know.) For our purposes, this will also be a `TEXT` type.
|
||||
|
||||
The SQL to create this table is
|
||||
|
||||
```sql
|
||||
CREATE TABLE config(
|
||||
name TEXT NOT NULL UNIQUE,
|
||||
value TEXT
|
||||
);
|
||||
```
|
||||
|
||||
Let's say we want to get the value of the key `author`. This is a `SELECT` statement away:
|
||||
|
||||
```sql
|
||||
SELECT value FROM config where name='author';
|
||||
```
|
||||
|
||||
Now let's say that we want to insert a new key into the table.
|
||||
|
||||
```sql
|
||||
INSERT INTO config(name, value) VALUES ('a', '1');
|
||||
```
|
||||
|
||||
What about updating?
|
||||
|
||||
```sql
|
||||
UPDATE config SET value='2' WHERE name='a';
|
||||
```
|
||||
|
||||
The tricky part is if we want to insert if the key does not exist, and update if it does. To handle this we'll need to resolve the [conflict](https://www.sqlite.org/lang_conflict.html).
|
||||
|
||||
```sql
|
||||
INSERT INTO config(name, value) VALUES ('a', '3') ON CONFLICT(name) DO UPDATE SET value=excluded.value;
|
||||
```
|
||||
|
||||
Lastly if you want to export the entire key-value store as a CSV:
|
||||
|
||||
```bash
|
||||
sqlite3 -header -csv data.db "SELECT * FROM config;"
|
||||
```
|
||||
|
||||
This is nice and all, but it's inconvinient to type out all these SQL commands. Therefore, I wrote two little bash scripts.
|
||||
|
||||
**`sqlite3_getkv`**
|
||||
|
||||
```bash
|
||||
#!/bin/sh
|
||||
|
||||
set -o errexit
|
||||
set -o nounset
|
||||
set -o pipefail
|
||||
|
||||
show_usage() {
|
||||
echo "Usage: sqlite3_getkv [db_file] [key]"
|
||||
exit 1
|
||||
}
|
||||
|
||||
# Check argument count
|
||||
if [ "$#" -ne 2 ]; then
|
||||
show_usage
|
||||
fi
|
||||
|
||||
# Initalize database file is not already
|
||||
sqlite3 "$1" "CREATE TABLE IF NOT EXISTS config(name TEXT NOT NULL UNIQUE, value TEXT);"
|
||||
|
||||
# Get value from key
|
||||
sqlite3 "$1" "SELECT value FROM CONFIG where name='$2';"
|
||||
|
||||
```
|
||||
|
||||
**`ssqlite3_setkv`**
|
||||
|
||||
```bash
|
||||
#!/bin/sh
|
||||
|
||||
set -o errexit
|
||||
set -o nounset
|
||||
set -o pipefail
|
||||
|
||||
show_usage() {
|
||||
echo "Usage: sqlite3_setkv [db_file] [key] [value]"
|
||||
exit 1
|
||||
}
|
||||
|
||||
# Check argument count
|
||||
if [ "$#" -ne 3 ]; then
|
||||
show_usage
|
||||
fi
|
||||
|
||||
# Initalize database file is not already
|
||||
sqlite3 "$1" "CREATE TABLE IF NOT EXISTS config(name TEXT NOT NULL UNIQUE, value TEXT);"
|
||||
|
||||
# Set key-value pair
|
||||
sqlite3 "$1" "INSERT INTO config(name, value) VALUES ('$2', '$3') ON CONFLICT(name) DO UPDATE SET value=excluded.value;"
|
||||
```
|
||||
|
||||
**Example Usage:**
|
||||
|
||||
```
|
||||
$ ./sqlite3_setkv.sh test.db a 4
|
||||
$ ./sqlite3_setkv.sh test.db c 5
|
||||
$ ./sqlite3_getkv.sh test.db a
|
||||
4
|
||||
$ ./sqlite3_setkv.sh test.db a 5
|
||||
$ ./sqlite3_getkv.sh test.db a
|
||||
5
|
||||
```
|
||||
|
||||
[^1]: Somehow my idea of easier, simpler, and more maintainable is writing bash scripts.
|
||||
|
Loading…
Reference in a new issue