Make rolling session more resilient in case of long finality stalls (#6106)

* Impl dynamic window size. Keep sessions for unfinalized chain Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * feedback Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * Stretch also in contructor plus tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * review feedback Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix approval-voting tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * grunting: dispute coordinator tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * add session window column Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * integrate approval vote and fix tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix rolling session tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * Small refactor Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * WIP, tests failing Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * Fix approval voting tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix dispute-coordinator tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * remove uneeded param Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fmt Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix loose ends Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * allow failure and tests for it Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix comment Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * comment fix Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * style fix Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * new col doesn't need to be ordered Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fmt and spellcheck Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * db persist tests Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * Add v2 config and cols Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * DB upgrade WIP Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * Fix comments Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * add todo Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * update to parity-db to "0.4.2" Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * migration complete Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * One session window size Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix merge damage Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix build errors Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fmt Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * comment fix Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix build Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * make error more explicit Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * add comment Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * refactor conflict merge Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * rename col_data Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * add doc comment Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * fix build Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> * migration: move all cols to v2 Signed-off-by: Andrei Sandu <andrei-mihail@parity.io> Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>
2026-07-24 20:35:41 +00:00 · 2022-11-08 19:16:31 +02:00
parent be4b5fad47
commit c261353380
15 changed files with 944 additions and 291 deletions
@@ -90,41 +90,45 @@ impl Backend for DbBackend {
 			match op {
 				BackendWriteOp::WriteStoredBlockRange(stored_block_range) => {
 					tx.put_vec(
-						self.config.col_data,
+						self.config.col_approval_data,
 						&STORED_BLOCKS_KEY,
 						stored_block_range.encode(),
 					);
 				},
 				BackendWriteOp::DeleteStoredBlockRange => {
-					tx.delete(self.config.col_data, &STORED_BLOCKS_KEY);
+					tx.delete(self.config.col_approval_data, &STORED_BLOCKS_KEY);
 				},
 				BackendWriteOp::WriteBlocksAtHeight(h, blocks) => {
-					tx.put_vec(self.config.col_data, &blocks_at_height_key(h), blocks.encode());
+					tx.put_vec(
+						self.config.col_approval_data,
+						&blocks_at_height_key(h),
+						blocks.encode(),
+					);
 				},
 				BackendWriteOp::DeleteBlocksAtHeight(h) => {
-					tx.delete(self.config.col_data, &blocks_at_height_key(h));
+					tx.delete(self.config.col_approval_data, &blocks_at_height_key(h));
 				},
 				BackendWriteOp::WriteBlockEntry(block_entry) => {
 					let block_entry: BlockEntry = block_entry.into();
 					tx.put_vec(
-						self.config.col_data,
+						self.config.col_approval_data,
 						&block_entry_key(&block_entry.block_hash),
 						block_entry.encode(),
 					);
 				},
 				BackendWriteOp::DeleteBlockEntry(hash) => {
-					tx.delete(self.config.col_data, &block_entry_key(&hash));
+					tx.delete(self.config.col_approval_data, &block_entry_key(&hash));
 				},
 				BackendWriteOp::WriteCandidateEntry(candidate_entry) => {
 					let candidate_entry: CandidateEntry = candidate_entry.into();
 					tx.put_vec(
-						self.config.col_data,
+						self.config.col_approval_data,
 						&candidate_entry_key(&candidate_entry.candidate.hash()),
 						candidate_entry.encode(),
 					);
 				},
 				BackendWriteOp::DeleteCandidateEntry(candidate_hash) => {
-					tx.delete(self.config.col_data, &candidate_entry_key(&candidate_hash));
+					tx.delete(self.config.col_approval_data, &candidate_entry_key(&candidate_hash));
 				},
 			}
 		}
@@ -149,7 +153,9 @@ pub type Bitfield = BitVec<u8, BitOrderLsb0>;
 #[derive(Debug, Clone, Copy)]
 pub struct Config {
 	/// The column family in the database where data is stored.
-	pub col_data: u32,
+	pub col_approval_data: u32,
+	/// The column of the database where rolling session window data is stored.
+	pub col_session_data: u32,
 }

 /// Details pertaining to our assignment on a block.
@@ -243,10 +249,10 @@ pub type Result<T> = std::result::Result<T, Error>;

 pub(crate) fn load_decode<D: Decode>(
 	store: &dyn Database,
-	col_data: u32,
+	col_approval_data: u32,
 	key: &[u8],
 ) -> Result<Option<D>> {
-	match store.get(col_data, key)? {
+	match store.get(col_approval_data, key)? {
 		None => Ok(None),
 		Some(raw) => D::decode(&mut &raw[..]).map(Some).map_err(Into::into),
 	}
@@ -303,7 +309,7 @@ pub fn load_stored_blocks(
 	store: &dyn Database,
 	config: &Config,
 ) -> SubsystemResult<Option<StoredBlockRange>> {
-	load_decode(store, config.col_data, STORED_BLOCKS_KEY)
+	load_decode(store, config.col_approval_data, STORED_BLOCKS_KEY)
 		.map_err(|e| SubsystemError::with_origin("approval-voting", e))
 }

@@ -313,7 +319,7 @@ pub fn load_blocks_at_height(
 	config: &Config,
 	block_number: &BlockNumber,
 ) -> SubsystemResult<Vec<Hash>> {
-	load_decode(store, config.col_data, &blocks_at_height_key(*block_number))
+	load_decode(store, config.col_approval_data, &blocks_at_height_key(*block_number))
 		.map(|x| x.unwrap_or_default())
 		.map_err(|e| SubsystemError::with_origin("approval-voting", e))
 }
@@ -324,7 +330,7 @@ pub fn load_block_entry(
 	config: &Config,
 	block_hash: &Hash,
 ) -> SubsystemResult<Option<BlockEntry>> {
-	load_decode(store, config.col_data, &block_entry_key(block_hash))
+	load_decode(store, config.col_approval_data, &block_entry_key(block_hash))
 		.map(|u: Option<BlockEntry>| u.map(|v| v.into()))
 		.map_err(|e| SubsystemError::with_origin("approval-voting", e))
 }
@@ -335,7 +341,7 @@ pub fn load_candidate_entry(
 	config: &Config,
 	candidate_hash: &CandidateHash,
 ) -> SubsystemResult<Option<CandidateEntry>> {
-	load_decode(store, config.col_data, &candidate_entry_key(candidate_hash))
+	load_decode(store, config.col_approval_data, &candidate_entry_key(candidate_hash))
 		.map(|u: Option<CandidateEntry>| u.map(|v| v.into()))
 		.map_err(|e| SubsystemError::with_origin("approval-voting", e))
 }
@@ -28,9 +28,12 @@ use std::{collections::HashMap, sync::Arc};
 use ::test_helpers::{dummy_candidate_receipt, dummy_candidate_receipt_bad_sig, dummy_hash};

 const DATA_COL: u32 = 0;
-const NUM_COLUMNS: u32 = 1;
+const SESSION_DATA_COL: u32 = 1;

-const TEST_CONFIG: Config = Config { col_data: DATA_COL };
+const NUM_COLUMNS: u32 = 2;
+
+const TEST_CONFIG: Config =
+	Config { col_approval_data: DATA_COL, col_session_data: SESSION_DATA_COL };

 fn make_db() -> (DbBackend, Arc<dyn Database>) {
 	let db = kvdb_memorydb::create(NUM_COLUMNS);
@@ -632,14 +632,15 @@ pub(crate) mod tests {
 	pub(crate) use sp_runtime::{Digest, DigestItem};
 	use std::{pin::Pin, sync::Arc};

-	use crate::{
-		approval_db::v1::Config as DatabaseConfig, criteria, BlockEntry, APPROVAL_SESSIONS,
-	};
+	use crate::{approval_db::v1::Config as DatabaseConfig, criteria, BlockEntry};

 	const DATA_COL: u32 = 0;
-	const NUM_COLUMNS: u32 = 1;
+	const SESSION_DATA_COL: u32 = 1;

-	const TEST_CONFIG: DatabaseConfig = DatabaseConfig { col_data: DATA_COL };
+	const NUM_COLUMNS: u32 = 2;
+
+	const TEST_CONFIG: DatabaseConfig =
+		DatabaseConfig { col_approval_data: DATA_COL, col_session_data: SESSION_DATA_COL };
 	#[derive(Default)]
 	struct MockClock;

@@ -654,22 +655,23 @@ pub(crate) mod tests {
 	}

 	fn blank_state() -> State {
+		let db = kvdb_memorydb::create(NUM_COLUMNS);
+		let db = polkadot_node_subsystem_util::database::kvdb_impl::DbAdapter::new(db, &[]);
+		let db: Arc<dyn Database> = Arc::new(db);
 		State {
 			session_window: None,
 			keystore: Arc::new(LocalKeystore::in_memory()),
 			slot_duration_millis: 6_000,
 			clock: Box::new(MockClock::default()),
 			assignment_criteria: Box::new(MockAssignmentCriteria),
+			db,
+			db_config: TEST_CONFIG,
 		}
 	}

 	fn single_session_state(index: SessionIndex, info: SessionInfo) -> State {
 		State {
-			session_window: Some(RollingSessionWindow::with_session_info(
-				APPROVAL_SESSIONS,
-				index,
-				vec![info],
-			)),
+			session_window: Some(RollingSessionWindow::with_session_info(index, vec![info])),
 			..blank_state()
 		}
 	}
@@ -782,11 +784,8 @@ pub(crate) mod tests {
 				.map(|(r, c, g)| (r.hash(), r.clone(), *c, *g))
 				.collect::<Vec<_>>();

-			let session_window = RollingSessionWindow::with_session_info(
-				APPROVAL_SESSIONS,
-				session,
-				vec![session_info],
-			);
+			let session_window =
+				RollingSessionWindow::with_session_info(session, vec![session_info]);

 			let header = header.clone();
 			Box::pin(async move {
@@ -891,11 +890,8 @@ pub(crate) mod tests {
 			.collect::<Vec<_>>();

 		let test_fut = {
-			let session_window = RollingSessionWindow::with_session_info(
-				APPROVAL_SESSIONS,
-				session,
-				vec![session_info],
-			);
+			let session_window =
+				RollingSessionWindow::with_session_info(session, vec![session_info]);

 			let header = header.clone();
 			Box::pin(async move {
@@ -1089,11 +1085,8 @@ pub(crate) mod tests {
 				.map(|(r, c, g)| (r.hash(), r.clone(), *c, *g))
 				.collect::<Vec<_>>();

-			let session_window = Some(RollingSessionWindow::with_session_info(
-				APPROVAL_SESSIONS,
-				session,
-				vec![session_info],
-			));
+			let session_window =
+				Some(RollingSessionWindow::with_session_info(session, vec![session_info]));

 			let header = header.clone();
 			Box::pin(async move {
@@ -1304,38 +1297,6 @@ pub(crate) mod tests {
 				}
 			);

-			// Caching of sesssions needs sessoion of first unfinalied block.
-			assert_matches!(
-				handle.recv().await,
-				AllMessages::ChainApi(ChainApiMessage::FinalizedBlockNumber(
-					s_tx,
-				)) => {
-					let _ = s_tx.send(Ok(header.number));
-				}
-			);
-
-			assert_matches!(
-				handle.recv().await,
-				AllMessages::ChainApi(ChainApiMessage::FinalizedBlockHash(
-					block_number,
-					s_tx,
-				)) => {
-					assert_eq!(block_number, header.number);
-					let _ = s_tx.send(Ok(Some(header.hash())));
-				}
-			);
-
-			assert_matches!(
-				handle.recv().await,
-				AllMessages::RuntimeApi(RuntimeApiMessage::Request(
-					h,
-					RuntimeApiRequest::SessionIndexForChild(s_tx),
-				)) => {
-					assert_eq!(h, header.hash());
-					let _ = s_tx.send(Ok(session));
-				}
-			);
-
 			// determine_new_blocks exits early as the parent_hash is in the DB

 			assert_matches!(
@@ -44,8 +44,7 @@ use polkadot_node_subsystem_util::{
 	database::Database,
 	metrics::{self, prometheus},
 	rolling_session_window::{
-		new_session_window_size, RollingSessionWindow, SessionWindowSize, SessionWindowUpdate,
-		SessionsUnavailable,
+		DatabaseParams, RollingSessionWindow, SessionWindowUpdate, SessionsUnavailable,
 	},
 	TimeoutExt,
 };
@@ -97,8 +96,6 @@ use crate::{
 #[cfg(test)]
 mod tests;

-pub const APPROVAL_SESSIONS: SessionWindowSize = new_session_window_size!(6);
-
 const APPROVAL_CHECKING_TIMEOUT: Duration = Duration::from_secs(120);
 /// How long are we willing to wait for approval signatures?
 ///
@@ -118,7 +115,9 @@ const LOG_TARGET: &str = "parachain::approval-voting";
 #[derive(Debug, Clone)]
 pub struct Config {
 	/// The column family in the DB where approval-voting data is stored.
-	pub col_data: u32,
+	pub col_approval_data: u32,
+	/// The of the DB where rolling session info is stored.
+	pub col_session_data: u32,
 	/// The slot duration of the consensus algorithm, in milliseconds. Should be evenly
 	/// divisible by 500.
 	pub slot_duration_millis: u64,
@@ -358,7 +357,10 @@ impl ApprovalVotingSubsystem {
 			keystore,
 			slot_duration_millis: config.slot_duration_millis,
 			db,
-			db_config: DatabaseConfig { col_data: config.col_data },
+			db_config: DatabaseConfig {
+				col_approval_data: config.col_approval_data,
+				col_session_data: config.col_session_data,
+			},
 			mode: Mode::Syncing(sync_oracle),
 			metrics,
 		}
@@ -367,7 +369,10 @@ impl ApprovalVotingSubsystem {
 	/// Revert to the block corresponding to the specified `hash`.
 	/// The operation is not allowed for blocks older than the last finalized one.
 	pub fn revert_to(&self, hash: Hash) -> Result<(), SubsystemError> {
-		let config = approval_db::v1::Config { col_data: self.db_config.col_data };
+		let config = approval_db::v1::Config {
+			col_approval_data: self.db_config.col_approval_data,
+			col_session_data: self.db_config.col_session_data,
+		};
 		let mut backend = approval_db::v1::DbBackend::new(self.db.clone(), config);
 		let mut overlay = OverlayedBackend::new(&backend);

@@ -634,6 +639,9 @@ struct State {
 	slot_duration_millis: u64,
 	clock: Box<dyn Clock + Send + Sync>,
 	assignment_criteria: Box<dyn AssignmentCriteria + Send + Sync>,
+	// Require for `RollingSessionWindow`.
+	db_config: DatabaseConfig,
+	db: Arc<dyn Database>,
 }

 #[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
@@ -655,8 +663,17 @@ impl State {
 		match session_window {
 			None => {
 				let sender = ctx.sender().clone();
-				self.session_window =
-					Some(RollingSessionWindow::new(sender, APPROVAL_SESSIONS, head).await?);
+				self.session_window = Some(
+					RollingSessionWindow::new(
+						sender,
+						head,
+						DatabaseParams {
+							db: self.db.clone(),
+							db_column: self.db_config.col_session_data,
+						},
+					)
+					.await?,
+				);
 				Ok(None)
 			},
 			Some(mut session_window) => {
@@ -751,7 +768,7 @@ async fn run<B, Context>(
 where
 	B: Backend,
 {
-	if let Err(err) = db_sanity_check(subsystem.db, subsystem.db_config) {
+	if let Err(err) = db_sanity_check(subsystem.db.clone(), subsystem.db_config.clone()) {
 		gum::warn!(target: LOG_TARGET, ?err, "Could not run approval vote DB sanity check");
 	}

@@ -761,6 +778,8 @@ where
 		slot_duration_millis: subsystem.slot_duration_millis,
 		clock,
 		assignment_criteria,
+		db_config: subsystem.db_config,
+		db: subsystem.db,
 	};

 	let mut wakeups = Wakeups::default();
@@ -14,6 +14,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.

+use crate::tests::test_constants::TEST_CONFIG;
+
 use super::*;
 use polkadot_node_primitives::{
 	approval::{
@@ -111,9 +113,12 @@ fn make_sync_oracle(val: bool) -> (Box<dyn SyncOracle + Send>, TestSyncOracleHan
 pub mod test_constants {
 	use crate::approval_db::v1::Config as DatabaseConfig;
 	const DATA_COL: u32 = 0;
-	pub(crate) const NUM_COLUMNS: u32 = 1;
+	const SESSION_DATA_COL: u32 = 1;

-	pub(crate) const TEST_CONFIG: DatabaseConfig = DatabaseConfig { col_data: DATA_COL };
+	pub(crate) const NUM_COLUMNS: u32 = 2;
+
+	pub(crate) const TEST_CONFIG: DatabaseConfig =
+		DatabaseConfig { col_approval_data: DATA_COL, col_session_data: SESSION_DATA_COL };
 }

 struct MockSupportsParachains;
@@ -487,8 +492,9 @@ fn test_harness<T: Future<Output = VirtualOverseer>>(
 		context,
 		ApprovalVotingSubsystem::with_config(
 			Config {
-				col_data: test_constants::TEST_CONFIG.col_data,
+				col_approval_data: test_constants::TEST_CONFIG.col_approval_data,
 				slot_duration_millis: SLOT_DURATION_MILLIS,
+				col_session_data: TEST_CONFIG.col_session_data,
 			},
 			Arc::new(db),
 			Arc::new(keystore),
@@ -810,38 +816,38 @@ async fn import_block(
 		}
 	);

-	assert_matches!(
-		overseer_recv(overseer).await,
-		AllMessages::ChainApi(ChainApiMessage::FinalizedBlockNumber(
-			s_tx,
-		)) => {
-			let _ = s_tx.send(Ok(number));
-		}
-	);
-
-	assert_matches!(
-		overseer_recv(overseer).await,
-		AllMessages::ChainApi(ChainApiMessage::FinalizedBlockHash(
-			block_number,
-			s_tx,
-		)) => {
-			assert_eq!(block_number, number);
-			let _ = s_tx.send(Ok(Some(hashes[number as usize].0)));
-		}
-	);
-
-	assert_matches!(
-		overseer_recv(overseer).await,
-		AllMessages::RuntimeApi(RuntimeApiMessage::Request(
-			h,
-			RuntimeApiRequest::SessionIndexForChild(s_tx),
-		)) => {
-			assert_eq!(h, hashes[number as usize].0);
-			let _ = s_tx.send(Ok(number.into()));
-		}
-	);
-
 	if !fork {
+		assert_matches!(
+			overseer_recv(overseer).await,
+			AllMessages::ChainApi(ChainApiMessage::FinalizedBlockNumber(
+				s_tx,
+			)) => {
+				let _ = s_tx.send(Ok(number));
+			}
+		);
+
+		assert_matches!(
+			overseer_recv(overseer).await,
+			AllMessages::ChainApi(ChainApiMessage::FinalizedBlockHash(
+				block_number,
+				s_tx,
+			)) => {
+				assert_eq!(block_number, number);
+				let _ = s_tx.send(Ok(Some(hashes[number as usize].0)));
+			}
+		);
+
+		assert_matches!(
+			overseer_recv(overseer).await,
+			AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+				h,
+				RuntimeApiRequest::SessionIndexForChild(s_tx),
+			)) => {
+				assert_eq!(h, hashes[number as usize].0);
+				let _ = s_tx.send(Ok(number.into()));
+			}
+		);
+
 		assert_matches!(
 			overseer_recv(overseer).await,
 			AllMessages::RuntimeApi(
@@ -99,10 +99,10 @@ impl DbBackend {
 			encoded = ?candidate_votes_session_prefix(index),
 			"Cleaning votes for session index"
 			);
-			tx.delete_prefix(self.config.col_data, &candidate_votes_session_prefix(index));
+			tx.delete_prefix(self.config.col_dispute_data, &candidate_votes_session_prefix(index));
 		}
 		// New watermark:
-		tx.put_vec(self.config.col_data, CLEANED_VOTES_WATERMARK_KEY, clean_until.encode());
+		tx.put_vec(self.config.col_dispute_data, CLEANED_VOTES_WATERMARK_KEY, clean_until.encode());
 		Ok(())
 	}
 }
@@ -148,21 +148,32 @@ impl Backend for DbBackend {
 					self.add_vote_cleanup_tx(&mut tx, session)?;

 					// Actually write the earliest session.
-					tx.put_vec(self.config.col_data, EARLIEST_SESSION_KEY, session.encode());
+					tx.put_vec(
+						self.config.col_dispute_data,
+						EARLIEST_SESSION_KEY,
+						session.encode(),
+					);
 				},
 				BackendWriteOp::WriteRecentDisputes(recent_disputes) => {
-					tx.put_vec(self.config.col_data, RECENT_DISPUTES_KEY, recent_disputes.encode());
+					tx.put_vec(
+						self.config.col_dispute_data,
+						RECENT_DISPUTES_KEY,
+						recent_disputes.encode(),
+					);
 				},
 				BackendWriteOp::WriteCandidateVotes(session, candidate_hash, votes) => {
 					gum::trace!(target: LOG_TARGET, ?session, "Writing candidate votes");
 					tx.put_vec(
-						self.config.col_data,
+						self.config.col_dispute_data,
 						&candidate_votes_key(session, &candidate_hash),
 						votes.encode(),
 					);
 				},
 				BackendWriteOp::DeleteCandidateVotes(session, candidate_hash) => {
-					tx.delete(self.config.col_data, &candidate_votes_key(session, &candidate_hash));
+					tx.delete(
+						self.config.col_dispute_data,
+						&candidate_votes_key(session, &candidate_hash),
+					);
 				},
 			}
 		}
@@ -195,7 +206,9 @@ fn candidate_votes_session_prefix(session: SessionIndex) -> [u8; 15 + 4] {
 #[derive(Debug, Clone)]
 pub struct ColumnConfiguration {
 	/// The column in the key-value DB where data is stored.
-	pub col_data: u32,
+	pub col_dispute_data: u32,
+	/// The column in the key-value DB where session data is stored.
+	pub col_session_data: u32,
 }

 /// Tracked votes on candidates, for the purposes of dispute resolution.
@@ -257,8 +270,12 @@ impl From<Error> for crate::error::Error {
 /// Result alias for DB errors.
 pub type Result<T> = std::result::Result<T, Error>;

-fn load_decode<D: Decode>(db: &dyn Database, col_data: u32, key: &[u8]) -> Result<Option<D>> {
-	match db.get(col_data, key)? {
+fn load_decode<D: Decode>(
+	db: &dyn Database,
+	col_dispute_data: u32,
+	key: &[u8],
+) -> Result<Option<D>> {
+	match db.get(col_dispute_data, key)? {
 		None => Ok(None),
 		Some(raw) => D::decode(&mut &raw[..]).map(Some).map_err(Into::into),
 	}
@@ -271,7 +288,7 @@ pub(crate) fn load_candidate_votes(
 	session: SessionIndex,
 	candidate_hash: &CandidateHash,
 ) -> SubsystemResult<Option<CandidateVotes>> {
-	load_decode(db, config.col_data, &candidate_votes_key(session, candidate_hash))
+	load_decode(db, config.col_dispute_data, &candidate_votes_key(session, candidate_hash))
 		.map_err(|e| SubsystemError::with_origin("dispute-coordinator", e))
 }

@@ -280,7 +297,7 @@ pub(crate) fn load_earliest_session(
 	db: &dyn Database,
 	config: &ColumnConfiguration,
 ) -> SubsystemResult<Option<SessionIndex>> {
-	load_decode(db, config.col_data, EARLIEST_SESSION_KEY)
+	load_decode(db, config.col_dispute_data, EARLIEST_SESSION_KEY)
 		.map_err(|e| SubsystemError::with_origin("dispute-coordinator", e))
 }

@@ -289,7 +306,7 @@ pub(crate) fn load_recent_disputes(
 	db: &dyn Database,
 	config: &ColumnConfiguration,
 ) -> SubsystemResult<Option<RecentDisputes>> {
-	load_decode(db, config.col_data, RECENT_DISPUTES_KEY)
+	load_decode(db, config.col_dispute_data, RECENT_DISPUTES_KEY)
 		.map_err(|e| SubsystemError::with_origin("dispute-coordinator", e))
 }

@@ -347,7 +364,7 @@ fn load_cleaned_votes_watermark(
 	db: &dyn Database,
 	config: &ColumnConfiguration,
 ) -> FatalResult<Option<SessionIndex>> {
-	load_decode(db, config.col_data, CLEANED_VOTES_WATERMARK_KEY)
+	load_decode(db, config.col_dispute_data, CLEANED_VOTES_WATERMARK_KEY)
 		.map_err(|e| FatalError::DbReadFailed(e))
 }

@@ -362,7 +379,7 @@ mod tests {
 		let db = kvdb_memorydb::create(1);
 		let db = polkadot_node_subsystem_util::database::kvdb_impl::DbAdapter::new(db, &[0]);
 		let store = Arc::new(db);
-		let config = ColumnConfiguration { col_data: 0 };
+		let config = ColumnConfiguration { col_dispute_data: 0, col_session_data: 1 };
 		DbBackend::new(store, config, Metrics::default())
 	}

@@ -35,7 +35,8 @@ use polkadot_node_subsystem::{
 	overseer, ActivatedLeaf, FromOrchestra, OverseerSignal, SpawnedSubsystem, SubsystemError,
 };
 use polkadot_node_subsystem_util::{
-	database::Database, rolling_session_window::RollingSessionWindow,
+	database::Database,
+	rolling_session_window::{DatabaseParams, RollingSessionWindow},
 };
 use polkadot_primitives::v2::{ScrapedOnChainVotes, ValidatorIndex, ValidatorPair};

@@ -117,12 +118,17 @@ pub struct DisputeCoordinatorSubsystem {
 #[derive(Debug, Clone, Copy)]
 pub struct Config {
 	/// The data column in the store to use for dispute data.
-	pub col_data: u32,
+	pub col_dispute_data: u32,
+	/// The data column in the store to use for session data.
+	pub col_session_data: u32,
 }

 impl Config {
 	fn column_config(&self) -> db::v1::ColumnConfiguration {
-		db::v1::ColumnConfiguration { col_data: self.col_data }
+		db::v1::ColumnConfiguration {
+			col_dispute_data: self.col_dispute_data,
+			col_session_data: self.col_session_data,
+		}
 	}
 }

@@ -199,17 +205,21 @@ impl DisputeCoordinatorSubsystem {
 		B: Backend + 'static,
 	{
 		loop {
-			let (first_leaf, rolling_session_window) = match get_rolling_session_window(ctx).await {
-				Ok(Some(update)) => update,
-				Ok(None) => {
-					gum::info!(target: LOG_TARGET, "received `Conclude` signal, exiting");
-					return Ok(None)
-				},
-				Err(e) => {
-					e.split()?.log();
-					continue
-				},
-			};
+			let db_params =
+				DatabaseParams { db: self.store.clone(), db_column: self.config.col_session_data };
+
+			let (first_leaf, rolling_session_window) =
+				match get_rolling_session_window(ctx, db_params).await {
+					Ok(Some(update)) => update,
+					Ok(None) => {
+						gum::info!(target: LOG_TARGET, "received `Conclude` signal, exiting");
+						return Ok(None)
+					},
+					Err(e) => {
+						e.split()?.log();
+						continue
+					},
+				};

 			let mut overlay_db = OverlayedBackend::new(&mut backend);
 			let (participations, votes, spam_slots, ordering_provider) = match self
@@ -352,12 +362,13 @@ impl DisputeCoordinatorSubsystem {
 #[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
 async fn get_rolling_session_window<Context>(
 	ctx: &mut Context,
+	db_params: DatabaseParams,
 ) -> Result<Option<(ActivatedLeaf, RollingSessionWindow)>> {
 	if let Some(leaf) = { wait_for_first_leaf(ctx) }.await? {
 		let sender = ctx.sender().clone();
 		Ok(Some((
 			leaf.clone(),
-			RollingSessionWindow::new(sender, DISPUTE_WINDOW, leaf.hash)
+			RollingSessionWindow::new(sender, leaf.hash, db_params)
 				.await
 				.map_err(JfyiError::RollingSessionWindow)?,
 		)))
@@ -176,7 +176,7 @@ impl Default for TestState {
 		let db = kvdb_memorydb::create(1);
 		let db = polkadot_node_subsystem_util::database::kvdb_impl::DbAdapter::new(db, &[]);
 		let db = Arc::new(db);
-		let config = Config { col_data: 0 };
+		let config = Config { col_dispute_data: 0, col_session_data: 1 };

 		let genesis_header = Header {
 			parent_hash: Hash::zero(),
@@ -251,6 +251,7 @@ impl TestState {
 		session: SessionIndex,
 	) {
 		// Order of messages is not fixed (different on initializing):
+		#[derive(Debug)]
 		struct FinishedSteps {
 			got_session_information: bool,
 			got_scraping_information: bool,
@@ -268,7 +269,8 @@ impl TestState {
 		let mut finished_steps = FinishedSteps::new();

 		while !finished_steps.is_done() {
-			match overseer_recv(virtual_overseer).await {
+			let recv = overseer_recv(virtual_overseer).await;
+			match recv {
 				AllMessages::RuntimeApi(RuntimeApiMessage::Request(
 					h,
 					RuntimeApiRequest::SessionIndexForChild(tx),
@@ -282,36 +284,38 @@ impl TestState {
 					let _ = tx.send(Ok(session));

 					// Queries for fetching earliest unfinalized block session. See `RollingSessionWindow`.
-					assert_matches!(
-						overseer_recv(virtual_overseer).await,
-						AllMessages::ChainApi(ChainApiMessage::FinalizedBlockNumber(
-							s_tx,
-						)) => {
-							let _ = s_tx.send(Ok(block_number));
-						}
-					);
+					if self.known_session.is_none() {
+						assert_matches!(
+							overseer_recv(virtual_overseer).await,
+							AllMessages::ChainApi(ChainApiMessage::FinalizedBlockNumber(
+								s_tx,
+							)) => {
+								let _ = s_tx.send(Ok(block_number));
+							}
+						);

-					assert_matches!(
-						overseer_recv(virtual_overseer).await,
-						AllMessages::ChainApi(ChainApiMessage::FinalizedBlockHash(
-							number,
-							s_tx,
-						)) => {
-							assert_eq!(block_number, number);
-							let _ = s_tx.send(Ok(Some(block_hash)));
-						}
-					);
+						assert_matches!(
+							overseer_recv(virtual_overseer).await,
+							AllMessages::ChainApi(ChainApiMessage::FinalizedBlockHash(
+								number,
+								s_tx,
+							)) => {
+								assert_eq!(block_number, number);
+								let _ = s_tx.send(Ok(Some(block_hash)));
+							}
+						);

-					assert_matches!(
-						overseer_recv(virtual_overseer).await,
-						AllMessages::RuntimeApi(RuntimeApiMessage::Request(
-							h,
-							RuntimeApiRequest::SessionIndexForChild(s_tx),
-						)) => {
-							assert_eq!(h, block_hash);
-							let _ = s_tx.send(Ok(session));
-						}
-					);
+						assert_matches!(
+							overseer_recv(virtual_overseer).await,
+							AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+								h,
+								RuntimeApiRequest::SessionIndexForChild(s_tx),
+							)) => {
+								assert_eq!(h, block_hash);
+								let _ = s_tx.send(Ok(session));
+							}
+						);
+					}

 					// No queries, if subsystem knows about this session already.
 					if self.known_session == Some(session) {
@@ -754,6 +758,7 @@ fn approval_vote_import_works() {
 			let approval_votes = [(ValidatorIndex(4), approval_vote.into_validator_signature())]
 				.into_iter()
 				.collect();
+
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash1, approval_votes)
 				.await;

@@ -2255,6 +2260,7 @@ fn resume_dispute_with_local_statement() {
 					},
 				})
 				.await;
+
 			handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
 				.await;

@@ -2469,6 +2475,7 @@ fn resume_dispute_with_local_statement_without_local_key() {
 			test_state
 		})
 	});
+
 	// No keys:
 	test_state.subsystem_keystore =
 		make_keystore(vec![Sr25519Keyring::Two.to_seed()].into_iter()).into();