Demonstrates Solana data account versioning used in supporting the Solana Cookbook article: Account Data Versioning

versioning-solana

This repo demonstrates ONE rudimentary way to upgrade/migrate account data changes with solana program changes.

What is data versioning?

Fundamentally to version data means to create a unique reference for a collection of data. This reference can take the form of a query, an ID, or also commonly a datetime identifier.

Simple scenario:

1. You create a program that stores a u64 value in your program's accounts data, assume you initialized the account and set somevalue to 50u64

2. Later on you decide that you want to also have some String value to reside in the account data that the rest of your program requires to be present

What do you do? There are a few options:

1. If the initial allocation of your program account has room to spare, and you had the foresite to include a 'data version' indicator in the account data: This repo will demonstrate an approach

2. If the initial allocation was sized specifically to the u64:

   • If you are running with a Solana version that incorporates the 'account re-allocation feature' (v 1.10.?) then leverage that
   • Otherwise, leveraging PDAs may help but someone else can demonstrate that

On with the show

In your initial planning, make sure to include a 'data version' field in your data. It can be a simple incrementing ordinal (e.g. u8) or something more sophisticated, up to you.

When creating the Program account, allocate enough space for data growth

Demonstration

First Version (data_version = 0)

1. Clone this repo
2. Change to repo folder
3. git checkout v0.0.1
4. Change to program folder
5. cargo build-bpf
6. Change back to repo folder
7. code .
8. Open the prechange.rs file in the main test folder
9. Click Run Test on fn test_load_pass()
10. Open the postchange.rs file 11 Click Run Test on fn test_pre_data_change_load_pass()
11. Exit code
12. mkdir stored
13. Open another terminal and change to this repo folder then
14. solana-test-validator -l ./.ledger
15. From the first folder terminal:
    • solana account -o stored/user1.json --output json-compact keys/accounts/user1_account.json
    • solana account -o stored/user2.json --output json-compact keys/accounts/user2_account.json
16. In the terminal running solana-test-validator hit Ctrl+C to kill it

This will create two accounts with somevalue to 1 and then modify each of their 1's value to 50u64. Steps 13 - 16 are to export the accounts from the ledger for use in the next steps.

First Version (data_version = 1)

1. From repo main folder run cargo clean
2. git checkout main
3. Change to program folder
4. cargo build-bpf
5. Change back to repo folder
6. code .
7. Open the postchange.rs file in the main test folder
8. Click Run Test on fn test_post_data_change_u2_pass()

The results will be as below