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core/vdbe: Fix BEGIN CONCURRENT transactions

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The transaction upgrade logic in Transaction opcode is total nonsense
for concurrent transactions so just drop it.

Fixes #3061
This commit is contained in:
Pekka Enberg
2025-09-12 21:19:34 +03:00
parent 1752266285
commit 86dcdad3d0
1 changed files with 5 additions and 32 deletions
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37
core/vdbe/execute.rs
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@@ -2180,38 +2180,11 @@ pub fn op_transaction(
&& matches!(new_transaction_state, TransactionState::Write { .. })
&& matches!(tx_mode, TransactionMode::Write)
{
// Handle upgrade from read to write transaction for MVCC
// Similar to non-MVCC path, we need to try upgrading to exclusive write transaction
turso_assert!(
!conn.is_nested_stmt.get(),
"nested stmt should not begin a new write transaction"
);
match mv_store.begin_exclusive_tx(pager.clone()) {
Ok(IOResult::Done(tx_id)) => {
// Successfully upgraded to exclusive write transaction
// Remove the old read transaction and replace with write transaction
conn.mv_transactions.borrow_mut().push(tx_id);
program.connection.mv_tx_id.set(Some(tx_id));
}
Err(LimboError::Busy) => {
// We failed to upgrade to write transaction so put the transaction into its original state.
// For MVCC, we don't need to end the transaction like in non-MVCC case, since MVCC transactions
// can be restarted automatically if they haven't performed any reads or writes yet.
// Just ensure the transaction state remains in its original state.
assert_eq!(conn.transaction_state.get(), current_state);
return Ok(InsnFunctionStepResult::Busy);
}
Ok(IOResult::IO(io)) => {
// set the transaction state to pending so we don't have to
// end the transaction.
program
.connection
.transaction_state
.replace(TransactionState::PendingUpgrade);
return Ok(InsnFunctionStepResult::IO(io));
}
Err(e) => return Err(e),
}
// For MVCC with concurrent transactions, we don't need to upgrade to exclusive.
// The existing MVCC transaction can handle both reads and writes.
// We only upgrade to exclusive for IMMEDIATE/EXCLUSIVE transaction modes.
// Since we already have an MVCC transaction from BEGIN CONCURRENT,
// we can just continue using it for writes.
}
} else {
if matches!(tx_mode, TransactionMode::Concurrent) {