Questions tagged [storage]
Questions about storing and accessing stored data on a Substrate blockchain.
237 questions
13
votes
2
answers
385
views
Is there a limit to the size of a map in Pallet storage?
If we are using a single or double maps in our pallets to store data on-chain, is there a limit to the number of records or size of one individual map?
I understand we should be storing the minimal ...
- 345
12
votes
1
answer
73
views
Automatically generating storage setter
When declaring storage items inside the runtime, we can automatically generate getters to query that storage item, for example (https://docs.substrate.io/v3/runtime/storage/#declaring-`storage-items`)`...
- 395
12
votes
1
answer
74
views
Multiple remove_all calls in same block
I stumbled upon an unexpected behavior when doing storage migration.
Problem Description
I want to clean-up a large DoubleStorageMap in multiple steps.
And that works just fine, however I also want to ...
- 597
11
votes
1
answer
323
views
How expensive is it to access storage items?
How expensive are storage reads and writes?
Does the cost depend on the size of the item?
- 9,322
11
votes
2
answers
459
views
How to use bounded vector for storage
I'm trying to use BoundedVec from frame_support for one of my storage items like this,
pub(super) type Payloads<T: Config> = StorageMap<_, Blake2_128Concat, T::BlockNumber, Vec<Payload>,...
- 135
10
votes
1
answer
138
views
How to manually remove storage items using Sudo?
I'm trying to remove a storage item on the relay chain, specifically a futureCode entry for a parachain.
I've seen that there's an extrinsic I can call system.killStorage(keys), however I have some ...
9
votes
3
answers
133
views
How to limit the number of values by prefix in StorageDoubleMap?
Say I have a StorageDoubleMap that stores Data structs for each user and ContextId
#[pallet::storage]
pub type Info<T: Config> = StorageDoubleMap<
_,
Blake2_128Concat,
...
- 501
9
votes
0
answers
104
views
What are the size limits of contract storage in ink?
Whilst reading the docs for ink I came across this warning:
CAUTION
If any type exhibiting Packed layout gets large enough (an ever-growing Vec might be a prime candidate for this), it will break ...
- 579
8
votes
2
answers
258
views
What's the overhead associated with the `#[transactional]` macro?
Substrate has a macro, #[transactional], to ensure that any modifications to storage are not persisted in case of an error during execution.
I imagine there's some sort of caching done before ...
- 1,091
8
votes
2
answers
220
views
How to check if StorageMap is empty?
I have created a simple storage map as follows and I just want to check if it's empty or not. I am comparing it with rust HashMaps, it has the is_empty() method to check. I intend to use this in the ...
- 537
8
votes
1
answer
243
views
Generating a Storage Key when making an RPC request
I'm trying to make an RPC call to a Substrate node, but I can't generate a proper Storage Key. The Module and Method parts are fine, the problem is the Twox64Concat part. The sp_core::twox_64 of value ...
- 460
8
votes
3
answers
233
views
Smart contract to IPFS communication
Assuming I was deployed a smart contract in a Parachain EVM wanting to cross out to IPFS to save or read data, what is the best way of achieving this in a decentralised way.
For example, doing this ...
- 421
7
votes
1
answer
64
views
How can I check whether a specific storage item was already accessed in the current block?
Inside a FRAME runtime I want to check whether a specific storage item was already read in the current block. Reason is to determine the impact of storage accesses across the extrinsics of a block ...
- 3,615
7
votes
1
answer
270
views
Prepare pallets for Weights v2
I am trying to prepare the pallets for Weights v2 at Encointer and a couple of questions arose.
Where can I find documentation on what exactly has to be done in terms of bounded types?
What is the ...
- 83
7
votes
2
answers
133
views
How to identify node update storage migrations?
I am working on Substrate-based node upgrades.
I stick to Polkadot releases and start from polkadot-v0.8.25 to the latest versions. While upgrading I need to make sure that I don’t miss any storage ...
6
votes
1
answer
122
views
What are good use cases for child tries
After reading the substrate documentation:
Child tries are useful when you want your own independent trie with a
separate root hash that you can use to verify the specific content in
that trie. ...
- 531
6
votes
1
answer
71
views
Is the full Merkle Trie copied in every block along with updates?
In the example given here:
Does each block save a copy of a Storage item?
Is the Merkle Trie copied to every block or is it the "diff" of the Merkle Trie that is updated on the new block?
...
- 8,455
6
votes
1
answer
148
views
How does `#[codec(mel_bound())]` work?
When declaring types, with generic parameters, to be stored in runtime storage, it’s common to see this pattern
#[derive(Encode, Decode, MaxEncodedLen, TypeInfo)]
pub struct MyItem<TypeA, TypeB> ...
- 501
6
votes
1
answer
86
views
Complexity of StorageDoubleMap::remove_prefix
The official documentation of StorageMaps states
An implementation of a map with a two keys.
It provides an important ability to efficiently remove all entries
that have a common first key.
https://...
- 461
6
votes
1
answer
62
views
Are Vec<T> stored with unused space in ink?
I'm using a Vec<T> in ink!. When allocating elements to the vec, the underlying array may be resized to provide a constant amortised push complexity of O(1). This means that sometimes the vec ...
- 579
6
votes
1
answer
75
views
What kind of information is stored in the State Trie?
I have read https://docs.substrate.io/v3/advanced/storage
And I am curious what is actually stored in the State Trie.
Are extrinsics and events stored in the State Trie?
- 8,455
6
votes
1
answer
49
views
How i define a 1 to N relation in storage?
i'm trying to define a 1 to N storage relation in my pallet. I have a Resource (owned by an account ) which will be linked to N Use structs ( kind of a set )
- Account #1
--> Resource #A
...
- 63
6
votes
1
answer
26
views
Nested runtime Api's `fn execute_in_transaction` calls no longer supported in v0.9.42?
When upgrading our codebase on top of substrate's polkadot-v0.9.42, we discovered it is no longer possible to make nested request to fn execute_in_transaction(call), from within the call.
Given in ...
- 61
5
votes
1
answer
190
views
Migrate keytype of StorageMap without breakin API
Assume we have a StorageMap MyMap of which we want to extend the type of the decoded keys from KeyTypeOld to an enum including the old type as well as a new one.
Before
pub type MyMap = StorageMap<...
5
votes
1
answer
139
views
Issue with #[pallet::generate_storage_info]
I was digging into substrate's storage_info macro https://docs.substrate.io/v3/runtime/macros/#palletgenerate_storage_info.
To get hands dirty checked code from
https://github.com/yourarj/substrate-...
- 327
5
votes
1
answer
283
views
How to weight `on_initialize`?
Is there any best practice how to count the weights in on_initialize correctly?
I read through the Polkadot and Substrate on_initialize weight calculations and couldn't always figure out: When to ...
- 543
5
votes
1
answer
153
views
How to create an iterator for a child storage trie?
I have a Storage Map which I am using to to store structs and a Storage Value to use for indexing this:
#[pallet::storage]
#[pallet::getter(fn consequences)]
/// Storage map holding basic Consequence ...
- 321
5
votes
1
answer
84
views
How do I upgrade an ink contract with storage changes?
Let's say I have a simple/contrived ink contract:
#[ink(storage)
pub struct MyContract {
a: u8,
b: u8,
}
Now let's say it's in production and a == 1 and b == 2.
I've done some work and ...
- 579
5
votes
2
answers
455
views
Storage Migration Guide Using #[pallet::storage]
I am new to both substrate and rust so trying to educate myself. I've the read documentation for both and am now going through the various tutorials and guides. I'm currently on the Basic Storage ...
- 321
5
votes
1
answer
44
views
Is the fully constructed State Trie persisted to disk?
On Substrate, is the fully constructed State Trie persisted to disk or only the State Trie root hash?
- 8,455
5
votes
1
answer
54
views
Fixed size array in ink smart contract storage
How can I have a fixed size array in my ink smart contract storage?
E.g.
// Contract storage
#[ink(storage)]
pub struct MyContract {
myArray: [u8; 64]
}
I get "the trait ...
- 579
5
votes
2
answers
83
views
How to determine if a parachain runtime migration is too big?
I want to write runtime storage migration for our parachain. This time it will scan large storage maps with more than 10k entries. This may results in very large PoV block size. I'm wondering what the ...
- 732
4
votes
2
answers
396
views
StorageHasher: Blake2 vs Twox
When creating a StorageMap, a hashing algorithm needs to be chosen for the StorageHasher.
frame_support provides a few options:
Identity
Blake2_128
Blake2_128Concat
Blake2_256
Twox64Concat
Twox128
...
- 1,727
4
votes
2
answers
155
views
Can I return a custom value from an extrinsic call
Looking at the docs, it seems I can only return custom weights in dispatchables
I want to be able to create data in storage then return the ID, because we will be calling the chain from a UI/Dapp
I am ...
- 1,233
4
votes
2
answers
96
views
Does each block save a copy of a Storage item?
This is what I read from the substrate storage docs: https://docs.substrate.io/v3/runtime/storage/
Runtime storage allows you to store data in your blockchain that is
persisted between blocks and can ...
- 1,009
4
votes
2
answers
254
views
How key-values database and Merkle Tree works together on Substrate
I have been looking deep dive into Substrate and trying to understand things behind the hood, especially storage API.
I am really keen to explore more in the Merkle abstraction between Storage API and ...
- 65
4
votes
2
answers
155
views
How to write pallet rename data migration?
I want to rename one of our collective pallet instances to be visible in the PolkaddotJs App.
I think the best option would be to migrate raw data.
I assume that all pallet data has the same trie path ...
- 198
4
votes
1
answer
177
views
How do I fix "SpecVersionNeedsToIncrease" error?
I Just clone this https://github.com/OAK-Foundation/substrate-node-template/tree/nicks-v2 for storage migration. After launch on polkadot ,this error shows:
I'm using following commands to run:
./...
- 2,100
4
votes
2
answers
447
views
access storage map from another pallet without trait pallet Config
I have one pallet with a storagemap that I want to use/call with another Pallet.
After doing some research I ran over Centrifuge fudge project(https://github.com/centrifuge/fudge/blob/...
- 369
4
votes
1
answer
139
views
BTreeMap storage type
I would like to store a large amount of sorted integers, they should be traversable with efficient get and insert.
If I can iterate over a storage map, could you let me know how?
Or is there a ...
- 227
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votes
1
answer
216
views
How to convert Account ID into Account Bytes in Hex using polkadot js?
I'm following this article about substrate keys. And I was unable to convert the account ID to account bytes in hex as it guides:
from this:
Account ID
...
- 417
4
votes
2
answers
325
views
How to build prefixed key for rocksdb
I would like to know how can the key for the state System Events storage can be built for a given block hash/height
- 41
4
votes
1
answer
124
views
Best Decentralised Storage for parachain?
Can anyone please explain what is the best decentralized storage protocol for storing pdf/images data on Polkadot parachain?
Actually, I gone through filecoin, Crust and Cess. Now I'm little confused ...
- 2,051
4
votes
1
answer
62
views
How much do data structures contribute towards ink contract storage size?
I've used Mapping, BTreeSet, BTreeMap and Vec for various purposes in our ink contract and have observed the contract size fluctuating based on usage of these four data structures. This leads me to ...
- 579
4
votes
2
answers
213
views
Read a value from offchain storage of a node
I want to read a single value from OffchainStorage of a live substrate node. Is it possible? Assume I can not use localStorageGet rpc request because it is an unsafe rpc.
- 91
4
votes
1
answer
103
views
What are the fees associated with ink! contract deployment?
I see that there are many events emitted during the process of deploying my contract on Substrate local chain (SNOW Network to be specific).
4 ICZ was reserved from deployer account
1 ICZ & 2 ICZ ...
- 304
4
votes
1
answer
86
views
How to iterate a large `StorageMap` over multiple extrinsic calls?
Hey valuable Substrate community,
I am running into the problem that I need to iterate over an unbounded StorageMap. So I need an IterationLimit and use an extrinsic which gets called multiple times.
...
- 543
4
votes
1
answer
112
views
What is a substate contracts max storage size? using the contracts pallet
Just to clarify, I am not asking about the max upload size of a contract. I am able to upload my contract to my chain no problem.
I have two smart contracts (A,B) A calls a transaction on smart ...
- 132
4
votes
1
answer
131
views
How do I recover quickly if the number of healthy nodes for my parachain reaches zero?
I'm particularly interested in the role of backups and state stored on disk in the recovery process. In terms of preparations, we are early enough in our project lifecycle to put in place whatever ...
- 141
4
votes
1
answer
64
views
Are there ways to suppress blockchain growth rate (in terms of storage)?
So during my testing I found out that with just 1 node running, on an npos consensus, my chain grew from 110 Mb to 990 Mb within two days. Is this expected? Are there strategies for controlling the ...
- 3,832