Dynamic storage sizes in solana

origami · February 6, 2022, 5:58pm

Can solana accounts support vectors of an interderminate size? If so, where can we see a working implementation of this?

zicklag · February 6, 2022, 8:38pm

Hi @origami and welcome to the forum!

Solana accounts, as of right now, are not easily re-sizable, so storing a dynamic length data such as a vector in a single account doesn’t work very well.

What you can do instead, though, is create multiple accounts, instead of storing them in a vector.

For instance, you use the JSON RPC Api to get a list of accounts owned by a certain program, such as your Solana program.

You can also filter that list of accounts by matching only accounts that have a certain value at a certain byte offset in the account data.

I did this in my Solana demo program:

github.com

zicklag/see-you-then/blob/master/solana_program/src/lib.rs

use borsh::{BorshDeserialize, BorshSchema, BorshSerialize};
use solana_program::{
    account_info::{next_account_info, AccountInfo},
    entrypoint,
    entrypoint::ProgramResult,
    instruction::{AccountMeta, Instruction},
    msg,
    program::invoke,
    program_error::ProgramError,
    pubkey::Pubkey,
    rent::Rent,
    system_instruction, system_program,
    sysvar::Sysvar,
};

entrypoint!(process_instruction);

#[derive(BorshDeserialize, BorshSerialize)]
pub enum SeeYouThenInstruction {
    /// Expected accounts when calling this instruction are

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In my app, you need to be able to create an unlimited number of time slot reservations, associated to a specific user.

Instead of storing a vector of time slot reservations, I create a new Solana account for each reservation, and my app can filter out reservations for specific users by matching on the part of the reservation account that is associated to a specific users wallet address.

I’d be happy to explain more if you have more questions!