Caching strategies in Supabase - Step-by-Step Execution

Process Flow - Caching strategies

Client Request

↓

Check Cache

↓

Return

↓

Store in Cache

↓

Return Data

When a client requests data, the system first checks the cache. If data is found (cache hit), it returns immediately. If not (cache miss), it fetches from the database, stores the result in cache, then returns it.

Execution Sample

Supabase

cache = {}
key = 'user:123'
if key in cache:
  data = cache[key]
else:
  data = db_fetch(key)
  cache[key] = data

This code checks if user data is in cache; if not, it fetches from the database and caches it.

Process Table

Step	Action	Cache State	Data Source	Result
1	Check if 'user:123' in cache	{}	N/A	Cache miss
2	Fetch 'user:123' from DB	{}	Database	Data fetched
3	Store 'user:123' data in cache	{'user:123': 'UserData'}	N/A	Cache updated
4	Return data to client	{'user:123': 'UserData'}	Cache	Data returned
5	Next request: Check cache	{'user:123': 'UserData'}	N/A	Cache hit
6	Return cached data	{'user:123': 'UserData'}	Cache	Data returned

💡 Execution stops after data is returned to client on cache hit or miss.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 6
cache	{}	{}	{'user:123': 'UserData'}	{'user:123': 'UserData'}
data	undefined	UserData	UserData	UserData

Key Moments - 3 Insights

Why do we check the cache before the database?

Checking the cache first (see Step 1 in execution_table) avoids slower database calls if data is already stored, improving speed.

What happens if data is not in the cache?

If cache miss occurs (Step 1), data is fetched from the database (Step 2) and then stored in cache (Step 3) for future requests.

Does the cache update every time we fetch data?

No, the cache updates only on a miss (Step 3). On a hit (Step 5), data is returned directly without updating cache.

Visual Quiz - 3 Questions

Look at the execution_table, what is the cache state after Step 3?

A {}

B undefined

C {'user:123': 'UserData'}

D {'user:124': 'UserData'}

💡 Hint

Check the 'Cache State' column in execution_table at Step 3.

At which step does the system fetch data from the database?

A Step 2

B Step 1

C Step 5

D Step 6

💡 Hint

Look at the 'Action' column in execution_table to find when DB fetch happens.

If the cache already contains 'user:123', which step returns data directly from cache?

A Step 2

B Step 5

C Step 3

D Step 1

💡 Hint

Check the 'Result' column for cache hit and data return.

Concept Snapshot

Caching strategies:
- Check cache first for requested data
- If cache hit, return data immediately
- If cache miss, fetch from database
- Store fetched data in cache
- Improves speed by reducing database calls
- Common in cloud apps like Supabase

Full Transcript

Caching strategies help speed up data access by storing data temporarily. When a client asks for data, the system first looks in the cache. If the data is there (cache hit), it returns it quickly. If not (cache miss), it fetches from the database, saves it in the cache, then returns it. This reduces slow database calls and improves performance. The example code shows checking the cache, fetching from the database if needed, and updating the cache. The execution table traces these steps clearly. Key moments include understanding why cache is checked first, what happens on a miss, and when cache updates occur. The quiz tests understanding of cache state and data flow steps.