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<title>RFC-0042: Add System version that replaces StateVersion on RuntimeVersion - Polkadot Fellowship RFCs</title>
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<ol class="chapter"><li class="chapter-item expanded affix "><a href="../introduction.html">Introduction</a></li><li class="spacer"></li><li class="chapter-item expanded affix "><li class="part-title">Newly Proposed</li><li class="spacer"></li><li class="chapter-item expanded affix "><li class="part-title">Proposed</li><li class="chapter-item expanded "><a href="../proposed/0150-voting-while-delegating.html">RFC-150: Allow Voting While Delegating</a></li><li class="chapter-item expanded "><a href="../proposed/0154-multi-slot-aura.html">RFC-0154: AURA Multi-Slot Collation </a></li><li class="chapter-item expanded "><a href="../proposed/0155-pUSD.html">RFC-0155: pUSD (Polkadot USD over-collateralised debt token)</a></li><li class="chapter-item expanded "><a href="../proposed/0156-bls-signatures.html">RFC-0156: Add BLS12-381 Host Functions</a></li><li class="spacer"></li><li class="chapter-item expanded affix "><li class="part-title">Approved</li><li class="chapter-item expanded "><a href="../approved/0001-agile-coretime.html">RFC-1: Agile Coretime</a></li><li class="chapter-item expanded "><a href="../approved/0005-coretime-interface.html">RFC-5: Coretime Interface</a></li><li class="chapter-item expanded "><a href="../approved/0007-system-collator-selection.html">RFC-0007: System Collator Selection</a></li><li class="chapter-item expanded "><a href="../approved/0008-parachain-bootnodes-dht.html">RFC-0008: Store parachain bootnodes in relay chain DHT</a></li><li class="chapter-item expanded "><a href="../approved/0009-improved-net-light-client-requests.html">RFC-0009: Improved light client requests networking protocol</a></li><li class="chapter-item expanded "><a href="../approved/0010-burn-coretime-revenue.html">RFC-0010: Burn Coretime Revenue</a></li><li class="chapter-item expanded "><a href="../approved/0012-process-for-adding-new-collectives.html">RFC-0012: Process for Adding New System Collectives</a></li><li class="chapter-item expanded "><a href="../approved/0013-prepare-blockbuilder-and-core-runtime-apis-for-mbms.html">RFC-0013: Prepare Core runtime API for MBMs</a></li><li class="chapter-item expanded "><a href="../approved/0014-improve-locking-mechanism-for-parachains.html">RFC-0014: Improve locking mechanism for parachains</a></li><li class="chapter-item expanded "><a href="../approved/0017-coretime-market-redesign.html">RFC-0017: Coretime Market Redesign</a></li><li class="chapter-item expanded "><a href="../approved/0022-adopt-encointer-runtime.html">RFC-0022: Adopt Encointer Runtime</a></li><li class="chapter-item expanded "><a href="../approved/0026-sassafras-consensus.html">RFC-0026: Sassafras Consensus Protocol</a></li><li class="chapter-item expanded "><a href="../approved/0032-minimal-relay.html">RFC-0032: Minimal Relay</a></li><li class="chapter-item expanded "><a href="../approved/0042-extrinsics-state-version.html" class="active">RFC-0042: Add System version that replaces StateVersion on RuntimeVersion</a></li><li class="chapter-item expanded "><a href="../approved/0043-storage-proof-size-hostfunction.html">RFC-0043: Introduce storage_proof_size Host Function for Improved Parachain Block Utilization</a></li><li class="chapter-item expanded "><a href="../approved/0045-nft-deposits-asset-hub.html">RFC-0045: Lowering NFT Deposits on Asset Hub</a></li><li class="chapter-item expanded "><a href="../approved/0047-assignment-of-availability-chunks.html">RFC-0047: Assignment of availability chunks to validators</a></li><li class="chapter-item expanded "><a href="../approved/0048-session-keys-runtime-api.html">RFC-0048: Generate ownership proof for SessionKeys</a></li><li class="chapter-item expanded "><a href="../approved/0050-fellowship-salaries.html">RFC-0050: Fellowship Salaries</a></li><li class="chapter-item expanded "><a href="../approved/0056-one-transaction-per-notification.html">RFC-0056: Enforce only one transaction per notification</a></li><li class="chapter-item expanded "><a href="../approved/0059-nodes-capabilities-discovery.html">RFC-0059: Add a discovery mechanism for nodes based on their capabilities</a></li><li class="chapter-item expanded "><a href="../approved/0078-merkleized-metadata.html">RFC-0078: Merkleized Metadata</a></li><li class="chapter-item expanded "><a href="../approved/0084-general-transaction-extrinsic-format.html">RFC-0084: General transactions in extrinsic format</a></li><li class="chapter-item expanded "><a href="../approved/0091-dht-record-creation-time.html">RFC-0091: DHT Authority discovery record creation time</a></li><li class="chapter-item expanded "><a href="../approved/0097-unbonding_queue.html">RFC-0097: Unbonding Queue</a></li><li class="chapter-item expanded "><a href="../approved/0099-transaction-extension-version.html">RFC-0099: Introduce a transaction extension version</a></li><li class="chapter-item expanded "><a href="../approved/0100-xcm-multi-type-asset-transfer.html">RFC-0100: New XCM instruction: InitiateAssetsTransfer</a></li><li class="chapter-item expanded "><a href="../approved/0101-xcm-transact-remove-max-weight-param.html">RFC-0101: XCM Transact remove require_weight_at_most parameter</a></li><li class="chapter-item expanded "><a href="../approved/0103-introduce-core-index-commitment.html">RFC-0103: Introduce a CoreIndex commitment and a SessionIndex field in candidate receipts</a></li><li class="chapter-item expanded "><a href="../approved/0105-xcm-improved-fee-mechanism.html">RFC-0105: XCM improved fee mechanism</a></li><li class="chapter-item expanded "><a href="../approved/0107-xcm-execution-hints.html">RFC-0107: XCM Execution hints</a></li><li class="chapter-item expanded "><a href="../approved/0108-xcm-remove-testnet-ids.html">RFC-0108: Remove XCM testnet NetworkIds</a></li><li class="chapter-item expanded "><a href="../approved/0122-alias-origin-on-asset-transfers.html">RFC-0122: Asset transfers can alias XCM origin on destination to original origin</a></li><li class="chapter-item expanded "><a href="../approved/0123-pending-code-as-storage-location-for-runtime-upgrades.html">RFC-0123: Introduce :pending_code as intermediate storage key for the runtime code</a></li><li class="chapter-item expanded "><a href="../approved/0125-xcm-asset-metadata.html">RFC-0125: XCM Asset Metadata</a></li><li class="chapter-item expanded "><a href="../approved/0126-introduce-pvq.html">RFC-0126: Introduce PVQ (PolkaVM Query)</a></li><li class="chapter-item expanded "><a href="../approved/0135-compressed-blob-prefixes.html">RFC-0135: Compressed Blob Prefixes</a></li><li class="chapter-item expanded "><a href="../approved/0139-faster-erasure-coding.html">RFC-0139: Faster Erasure Coding</a></li><li class="chapter-item expanded "><a href="../approved/0146-deflationary-fee-proposal.html">RFC-0146: Deflationary Transaction Fee Model for the Relay Chain and its System Parachains</a></li><li class="chapter-item expanded "><a href="../approved/0149-rfc-1-renewal-adjustment.html">RFC-0149: Renewal Adjustment</a></li><li class="spacer"></li><li class="chapter-item expanded affix "><li class="part-title">Stale</li><li class="chapter-item expanded "><a href="../stale/0000-pre-elves_soft.html">RFC-0000: Pre-ELVES soft concensus</a></li><li class="chapter-item expanded "><a href="../stale/0000-rewards.html">RFC-0000: Validator Rewards</a></li><li class="chapter-item expanded "><a href="../stale/0004-remove-unnecessary-allocator-usage.html">RFC-0004: Remove the host-side runtime memory allocator</a></li><li class="chapter-item expanded "><a href="../stale/0006-dynamic-pricing-for-bulk-coretime-sales.html">RFC-0006: Dynamic Pricing for Bulk Coretime Sales</a></li><li class="chapter-item expanded "><a href="../stale/0034-xcm-absolute-location-account-derivation.html">RFC-34: XCM Absolute Location Account Derivation</a></li><li class="chapter-item expanded "><a href="../stale/0035-conviction-voting-delegation-modifications.html"> RFC-0035: Conviction Voting Delegation Modifications</a></li><li class="chapter-item expanded "><a href="../stale/0044-rent-based-registration.html">RFC-0044: Rent based registration model</a></li><li class="chapter-item expanded "><a href="../stale/0054-remove-heap-pages.html">RFC-0054: Remove the concept of "heap pages" from the client</a></li><li class="chapter-item expanded "><a href="../stale/0070-x-track-kusamanetwork.html">RFC-0070: X Track for @kusamanetwork</a></li><li class="chapter-item expanded "><a href="../stale/0073-referedum-deposit-track.html">RFC-0073: Decision Deposit Referendum Track</a></li><li class="chapter-item expanded "><a href="../stale/0074-stateful-multisig-pallet.html">RFC-0074: Stateful Multisig Pallet</a></li><li class="chapter-item expanded "><a href="../stale/0077-increase-max-length-of-identity-pgp-fingerprint-value.html">RFC-0077: Increase maximum length of identity PGP fingerprint values from 20 bytes</a></li><li class="chapter-item expanded "><a href="../stale/0088-broker-pallet-slashable-deposit-purchaser-reputation-reserved-cores.html">RFC-0088: Add slashable locked deposit, purchaser reputation, and reserved cores for on-chain identities to broker pallet</a></li><li class="chapter-item expanded "><a href="../stale/00xx-secondary-marketplace-for-regions.html">RFC-0001: Secondary Market for Regions</a></li><li class="chapter-item expanded "><a href="../stale/00xx-smart-contracts-coretime-chain.html">RFC-0002: Smart Contracts on the Coretime Chain</a></li><li class="chapter-item expanded "><a href="../stale/0102-offchain-parachain-runtime-upgrades.html">RFC-0000: Feature Name Here</a></li><li class="chapter-item expanded "><a href="../stale/0106-xcm-remove-fees-mode.html">RFC-0106: Remove XCM fees mode</a></li><li class="chapter-item expanded "><a href="../stale/0111-pure-proxy-replication.html">RFC-0111: Pure Proxy Replication</a></li><li class="chapter-item expanded "><a href="../stale/0112-compress-state-response-message-in-state-sync.html">RFC-0112: Compress the State Response Message in State Sync</a></li><li class="chapter-item expanded "><a href="../stale/0114-secp256r1-hostfunction.html">RFC-0114: Introduce secp256r1_ecdsa_verify_prehashed Host Function to verify NIST-P256 elliptic curve signatures</a></li><li class="chapter-item expanded "><a href="../stale/0117-unbrick-collective.html">RFC-0117: The Unbrick Collective</a></li><li class="chapter-item expanded "><a href="../stale/0120-referenda-confirmation-by-candle-mechanism.html">RFC-0120: Referenda Confirmation by Candle Mechanism</a></li><li class="chapter-item expanded "><a href="../stale/0124-extrinsic-version-5.html">RFC-0124: Extrinsic version 5</a></li><li class="chapter-item expanded "><a href="../stale/0138-invulnerable-collator-election.html">RFC-0138: Election mechanism for invulnerable collators on system chains</a></li><li class="chapter-item expanded "><a href="../stale/0152-decentralized-convex-preference-coretime-market-for-polkadot.html">RFC-0152: Decentralized Convex-Preference Coretime Market for Polkadot</a></li><li class="chapter-item expanded "><a href="../stale/RFC-114 Adjust Tipper Track Confirmation Periods.html">RFC-114: Adjust Tipper Track Confirmation Periods</a></li><li class="chapter-item expanded "><a href="../stale/TODO-stale-nomination-reward-curve.html">RFC-TODO: Stale Nomination Reward Curve</a></li><li class="chapter-item expanded "><a href="../stale/xxxx-improve-the-security-of-proof-of-possession.html">RFC-XXXX: Adding customized mandatory context to proof of possession statement</a></li></ol>
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<p><a href="https://github.com/polkadot-fellows/RFCs/blob/main/text/0042-extrinsics-state-version.md">(source)</a></p>
<p><strong>Table of Contents</strong></p>
<ul>
<li><a href="#rfc-0042-add-system-version-that-replaces-stateversion-on-runtimeversion">RFC-0042: Add System version that replaces StateVersion on RuntimeVersion</a>
<ul>
<li><a href="#summary">Summary</a></li>
<li><a href="#motivation">Motivation</a></li>
<li><a href="#stakeholders">Stakeholders</a></li>
<li><a href="#explanation">Explanation</a></li>
<li><a href="#drawbacks">Drawbacks</a></li>
<li><a href="#testing-security-and-privacy">Testing, Security, and Privacy</a></li>
<li><a href="#performance-ergonomics-and-compatibility">Performance, Ergonomics, and Compatibility</a>
<ul>
<li><a href="#performance">Performance</a></li>
<li><a href="#ergonomics">Ergonomics</a></li>
<li><a href="#compatibility">Compatibility</a></li>
</ul>
</li>
<li><a href="#prior-art-and-references">Prior Art and References</a></li>
<li><a href="#unresolved-questions">Unresolved Questions</a></li>
<li><a href="#future-directions-and-related-material">Future Directions and Related Material</a></li>
</ul>
</li>
</ul>
<h1 id="rfc-0042-add-system-version-that-replaces-stateversion-on-runtimeversion"><a class="header" href="#rfc-0042-add-system-version-that-replaces-stateversion-on-runtimeversion">RFC-0042: Add System version that replaces StateVersion on RuntimeVersion</a></h1>
<div class="table-wrapper"><table><thead><tr><th></th><th></th></tr></thead><tbody>
<tr><td><strong>Start Date</strong></td><td>25th October 2023</td></tr>
<tr><td><strong>Description</strong></td><td>Add System Version and remove State Version</td></tr>
<tr><td><strong>Authors</strong></td><td>Vedhavyas Singareddi</td></tr>
</tbody></table>
</div>
<h2 id="summary"><a class="header" href="#summary">Summary</a></h2>
<p>At the moment, we have <code>system_version</code> field on <code>RuntimeVersion</code> that derives which state version is used for the
Storage.
We have a use case where we want extrinsics root is derived using <code>StateVersion::V1</code>. Without defining a new field
under <code>RuntimeVersion</code>,
we would like to propose adding <code>system_version</code> that can be used to derive both storage and extrinsic state version.</p>
<h2 id="motivation"><a class="header" href="#motivation">Motivation</a></h2>
<p>Since the extrinsic state version is always <code>StateVersion::V0</code>, deriving extrinsic root requires full extrinsic data.
This would be problematic when we need to verify the extrinsics root if the extrinsic sizes are bigger. This problem is
further explored in https://github.com/polkadot-fellows/RFCs/issues/19</p>
<p>For <code>Subspace</code> project, we have an enshrined rollups called <code>Domain</code> with optimistic verification and Fraud proofs are
used to detect malicious behavior.
One of the <code>Fraud proof</code> variant is to derive <code>Domain</code> block extrinsic root on <code>Subspace</code>'s consensus chain.
Since <code>StateVersion::V0</code> requires full extrinsic data, we are forced to pass all the extrinsics through the Fraud proof.
One of the main challenge here is some extrinsics could be big enough that this variant of Fraud proof may not be
included in the Consensus block due to Block's weight restriction.
If the extrinsic root is derived using <code>StateVersion::V1</code>, then we do not need to pass the full extrinsic data but
rather at maximum, 32 byte of extrinsic data.</p>
<h2 id="stakeholders"><a class="header" href="#stakeholders">Stakeholders</a></h2>
<ul>
<li>Technical Fellowship, in its role of maintaining system runtimes.</li>
</ul>
<h2 id="explanation"><a class="header" href="#explanation">Explanation</a></h2>
<p>In order to use project specific StateVersion for extrinsic roots, we proposed
an <a href="https://github.com/paritytech/polkadot-sdk/pull/1691">implementation</a> that introduced
parameter to <code>frame_system::Config</code> but that unfortunately did not feel correct.
So we would like to <a href="https://github.com/paritytech/polkadot-sdk/pull/1968">propose</a> adding this change to
the <code>RuntimeVersion</code>
object. The system version, if introduced, will be used to derive both storage and extrinsic state version.
If system version is <code>0</code>, then both Storage and Extrinsic State version would use V0.
If system version is <code>1</code>, then Storage State version would use V1 and Extrinsic State version would use V0.
If system version is <code>2</code>, then both Storage and Extrinsic State version would use V1.</p>
<p>If implemented, the new <code>RuntimeVersion</code> definition would look something similar to</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>/// Runtime version (Rococo).
#[sp_version::runtime_version]
pub const VERSION: RuntimeVersion = RuntimeVersion {
spec_name: create_runtime_str!(&quot;rococo&quot;),
impl_name: create_runtime_str!(&quot;parity-rococo-v2.0&quot;),
authoring_version: 0,
spec_version: 10020,
impl_version: 0,
apis: RUNTIME_API_VERSIONS,
transaction_version: 22,
system_version: 1,
};
<span class="boring">}</span></code></pre></pre>
<h2 id="drawbacks"><a class="header" href="#drawbacks">Drawbacks</a></h2>
<p>There should be no drawbacks as it would replace <code>state_version</code> with same behavior but documentation should be updated
so that chains know which <code>system_version</code> to use.</p>
<h2 id="testing-security-and-privacy"><a class="header" href="#testing-security-and-privacy">Testing, Security, and Privacy</a></h2>
<p>AFAIK, should not have any impact on the security or privacy.</p>
<h2 id="performance-ergonomics-and-compatibility"><a class="header" href="#performance-ergonomics-and-compatibility">Performance, Ergonomics, and Compatibility</a></h2>
<p>These changes should be compatible for existing chains if they use <code>state_version</code> value for <code>system_verision</code>.</p>
<h3 id="performance"><a class="header" href="#performance">Performance</a></h3>
<p>I do not believe there is any performance hit with this change.</p>
<h3 id="ergonomics"><a class="header" href="#ergonomics">Ergonomics</a></h3>
<p>This does not break any exposed Apis.</p>
<h3 id="compatibility"><a class="header" href="#compatibility">Compatibility</a></h3>
<p>This change should not break any compatibility.</p>
<h2 id="prior-art-and-references"><a class="header" href="#prior-art-and-references">Prior Art and References</a></h2>
<p>We <a href="https://github.com/paritytech/polkadot-sdk/pull/1691">proposed</a> introducing a similar change by introducing a
parameter to <code>frame_system::Config</code> but did not feel that
is the correct way of introducing this change.</p>
<h2 id="unresolved-questions"><a class="header" href="#unresolved-questions">Unresolved Questions</a></h2>
<p>I do not have any specific questions about this change at the moment.</p>
<h2 id="future-directions-and-related-material"><a class="header" href="#future-directions-and-related-material">Future Directions and Related Material</a></h2>
<p>IMO, this change is pretty self-contained and there won't be any future work necessary. </p>
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