Gas optimization with storage in Blockchain / Solidity - Step-by-Step Execution

Concept Flow - Gas optimization with storage

Start Transaction

↓

Check Storage Usage

↓

Is Storage Write Needed?

No→Skip Write

Yes↓

Write to Storage (Expensive)

↓

Use Memory/Stack if Possible (Cheaper)

↓

Minimize Storage Writes

↓

End Transaction

This flow shows how to decide when to write to storage to save gas by minimizing expensive storage operations.

Execution Sample

Blockchain / Solidity

uint256 storageVar;

function update() public {
  uint256 x = 5;
  uint256 y;
  y = x + 10; // memory operation
  storageVar = y; // storage write
}

This code updates a storage variable by first calculating in memory, then writing once to storage to save gas.

Execution Table

Step	Operation	Variable	Value	Gas Cost	Note
1	Initialize x	x	5	0	x is in memory, no gas cost
2	Declare y	y	0	0	y is uninitialized
3	Calculate y = x + 10	y	15	Low	Calculation in memory, cheap
4	Write y to storageVar	storageVar	15	High	Storage write is expensive
5	End function	-	-	0	Transaction ends

💡 Function ends after one storage write to minimize gas

Variable Tracker

Variable	Start	After Step 3	After Step 4	Final
x	5	5	5	5
y	0	15	15	15
storageVar	0	0	15	15

Key Moments - 2 Insights

Why do we calculate y in memory before writing to storageVar?

Calculating y in memory (Step 3) is cheaper than multiple storage writes. Writing once to storage (Step 4) saves gas by minimizing expensive storage operations.

What makes storage writes expensive compared to memory operations?

Storage writes (Step 4) cost more gas because they change blockchain state permanently, unlike memory calculations (Step 3) which are temporary and cheaper.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of y after Step 3?

A 15

B 5

C 0

D 10

💡 Hint

Check the 'Value' column for y at Step 3 in the execution table

At which step does the expensive storage write happen?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look for 'Storage write is expensive' note in the execution table

If we wrote to storageVar twice instead of once, how would gas cost change?

A Gas cost would stay the same

B Gas cost would increase

C Gas cost would decrease

D Gas cost would be zero

💡 Hint

Refer to the 'Gas Cost' column and note that storage writes are expensive

Concept Snapshot

Gas optimization with storage:
- Storage writes cost high gas
- Use memory/stack for calculations
- Write to storage only once when needed
- Minimize storage writes to save gas
- Calculate values in memory before storage update

Full Transcript

This visual trace shows how gas optimization works by minimizing storage writes. First, variables are initialized in memory with no gas cost. Calculations happen in memory, which is cheap. Then, only one storage write is done to update the blockchain state, which is expensive. By reducing storage writes, the contract saves gas. The variable tracker shows values changing step-by-step. Key moments explain why memory is preferred for calculations and why storage writes cost more. The quiz tests understanding of variable values and gas costs at each step.