Advanced Transaction Patterns

Geode provides enterprise-grade transaction management with comprehensive ACID compliance, advanced isolation levels, savepoint support, phantom read prevention, and sophisticated deadlock detection. This guide covers advanced transaction patterns for building robust, concurrent applications. <h3 id="transaction-fundamentals" class="position-relative d-flex align-items-center group"> Transaction Fundamentals <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="transaction-fundamentals" aria-haspopup="dialog" aria-label="Share link: Transaction Fundamentals"> Share link </button> </h3><div id="headingShareModal" class="heading-share-modal" role="dialog" aria-modal="true" aria-labelledby="headingShareTitle" hidden> <div class="hsm-dialog" role="document"> <div class="hsm-header"> <h2 id="headingShareTitle" class="h6 mb-0 fw-bold">Share this section</h2> <button type="button" class="hsm-close" aria-label="Close"> </button> </div> <div class="hsm-body"> <label for="headingShareInput" class="form-label small text-muted mb-1 text-uppercase fw-bold" style="font-size: 0.7rem; letter-spacing: 0.5px;">Permalink</label> <div class="input-group mb-4 hsm-url-group"> <input id="headingShareInput" type="text" class="form-control font-monospace" readonly aria-readonly="true" style="font-size: 0.85rem;" /> <button class="btn btn-primary hsm-copy" type="button" aria-label="Copy" title="Copy"> </button> </div> <div class="small fw-bold mb-2 text-muted text-uppercase" style="font-size: 0.7rem; 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} if(copyBtn && (e.target===copyBtn || (e.target.closest && e.target.closest('.hsm-copy')))) { e.preventDefault(); copyCurrent(); } }); document.addEventListener('keydown', e=>{ if(e.key==='Escape' && isOpen()) closeModal(); }); function trapFocus(){ if(trapBound) return; trapBound=true; modal.addEventListener('keydown', f=>{ if(f.key==='Tab' && isOpen()){ const focusable=[...modal.querySelectorAll('a[href],button,input,textarea,select,[tabindex]:not([tabindex="-1"])')].filter(el=>!el.hasAttribute('disabled')); if(!focusable.length) return; const first=focusable[0]; const last=focusable[focusable.length-1]; if(f.shiftKey && document.activeElement===first){ f.preventDefault(); last.focus(); } else if(!f.shiftKey && document.activeElement===last){ f.preventDefault(); first.focus(); } } }); } if(closeBtn) closeBtn.addEventListener('click', e=>{ e.preventDefault(); closeModal(); }); })(); </script> <h4 id="basic-transaction-lifecycle" class="position-relative d-flex align-items-center group"> Basic Transaction Lifecycle <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="basic-transaction-lifecycle" aria-haspopup="dialog" aria-label="Share link: Basic Transaction Lifecycle"> Share link </button> </h4>All transactions follow the standard ACID lifecycle: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Begin transaction START TRANSACTION; -- Perform operations CREATE (p:Person {name: 'Alice', age: 30}); CREATE (c:Company {name: 'TechCorp'}); CREATE (p)-[:WORKS_FOR {since: 2024}]->(c); -- Commit changes COMMIT; </code></pre></div>ACID Guarantees: <ul> <li>Atomicity: All operations succeed or all fail</li> <li>Consistency: Database remains in valid state</li> <li>Isolation: Concurrent transactions don’t interfere</li> <li>Durability: Committed changes persist after crash</li> </ul> <h4 id="rollback-on-error" class="position-relative d-flex align-items-center group"> Rollback on Error <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="rollback-on-error" aria-haspopup="dialog" aria-label="Share link: Rollback on Error"> Share link </button> </h4>Discard changes if an error occurs: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; CREATE (p:Person {name: 'Bob', age: 25}); CREATE (c:Company {name: 'Acme Inc'}); -- Decide to cancel ROLLBACK; </code></pre></div> <h4 id="transaction-state-persistence" class="position-relative d-flex align-items-center group"> Transaction State Persistence <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="transaction-state-persistence" aria-haspopup="dialog" aria-label="Share link: Transaction State Persistence"> Share link </button> </h4>Geode persists transaction state across CLI invocations within a session: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"># First command: start transaction geode query "START TRANSACTION" # Second command: perform operations (same session) geode query "CREATE (n:Test {id: 1})" # Third command: commit (same session) geode query "COMMIT" </code></pre></div>Implementation: Transaction state saved to session file, loaded before each query execution. <h3 id="savepoints" class="position-relative d-flex align-items-center group"> Savepoints <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="savepoints" aria-haspopup="dialog" aria-label="Share link: Savepoints"> Share link </button> </h3> <h4 id="creating-savepoints" class="position-relative d-flex align-items-center group"> Creating Savepoints <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="creating-savepoints" aria-haspopup="dialog" aria-label="Share link: Creating Savepoints"> Share link </button> </h4>Save intermediate points within a transaction for partial rollback: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Create initial data CREATE (p:Person {name: 'Alice', age: 30}); -- Create savepoint SAVEPOINT after_person; -- Create more data CREATE (c:Company {name: 'TechCorp'}); CREATE (p)-[:WORKS_FOR {since: 2024}]->(c); -- Create another savepoint SAVEPOINT after_company; -- More operations MATCH (p:Person {name: 'Alice'}) SET p.status = 'employed'; COMMIT; </code></pre></div> <h4 id="rolling-back-to-savepoints" class="position-relative d-flex align-items-center group"> Rolling Back to Savepoints <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="rolling-back-to-savepoints" aria-haspopup="dialog" aria-label="Share link: Rolling Back to Savepoints"> Share link </button> </h4>Rollback to specific savepoint without aborting entire transaction: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; CREATE (p:Person {name: 'Bob', age: 25}); SAVEPOINT person_created; CREATE (c:Company {name: 'Acme Inc'}); SAVEPOINT company_created; -- Oops, wrong company - rollback to person_created ROLLBACK TO person_created; -- Create correct company CREATE (c:Company {name: 'RealCorp'}); CREATE (p)-[:WORKS_FOR]->(c); COMMIT; </code></pre></div>Use Cases: <ul> <li>Complex multi-step operations with error recovery</li> <li>Batch imports with partial rollback on validation failure</li> <li>Nested logical operations requiring independent rollback</li> </ul> <h4 id="nested-savepoints" class="position-relative d-flex align-items-center group"> Nested Savepoints <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="nested-savepoints" aria-haspopup="dialog" aria-label="Share link: Nested Savepoints"> Share link </button> </h4>Create hierarchical savepoints for granular control: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Level 1: Create person CREATE (p:Person {name: 'Charlie', age: 35}); SAVEPOINT level1; -- Level 2: Create address CREATE (a:Address {street: '123 Main St', city: 'Seattle'}); CREATE (p)-[:LIVES_AT]->(a); SAVEPOINT level2; -- Level 3: Create phone CREATE (ph:Phone {number: '555-1234'}); CREATE (p)-[:HAS_PHONE]->(ph); SAVEPOINT level3; -- Error in phone validation - rollback only level 3 ROLLBACK TO level2; -- Try different phone CREATE (ph:Phone {number: '555-5678'}); CREATE (p)-[:HAS_PHONE]->(ph); COMMIT; </code></pre></div> <h3 id="isolation-levels" class="position-relative d-flex align-items-center group"> Isolation Levels <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="isolation-levels" aria-haspopup="dialog" aria-label="Share link: Isolation Levels"> Share link </button> </h3>Geode supports six isolation levels with different concurrency-consistency trade-offs: <h4 id="isolation-level-comparison" class="position-relative d-flex align-items-center group"> Isolation Level Comparison <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="isolation-level-comparison" aria-haspopup="dialog" aria-label="Share link: Isolation Level Comparison"> Share link </button> </h4><table> <thead> <tr> <th>Isolation Level</th> <th>Dirty Read</th> <th>Non-Repeatable Read</th> <th>Phantom Read</th> <th>Performance</th> <th>Use Case</th> </tr> </thead> <tbody> <tr> <td>Read Uncommitted</td> <td>✅ Allowed</td> <td>✅ Allowed</td> <td>✅ Allowed</td> <td>Highest</td> <td>Bulk operations, analytics</td> </tr> <tr> <td>Read Committed</td> <td>❌ Prevented</td> <td>✅ Allowed</td> <td>✅ Allowed</td> <td>High</td> <td>General queries</td> </tr> <tr> <td>Repeatable Read</td> <td>❌ Prevented</td> <td>❌ Prevented</td> <td>✅ Allowed</td> <td>Medium</td> <td>Analytical workloads</td> </tr> <tr> <td>Snapshot Isolation (Default)</td> <td>❌ Prevented</td> <td>❌ Prevented</td> <td>⚠️ Possible</td> <td>High</td> <td>High-concurrency OLTP</td> </tr> <tr> <td>Serializable Snapshot (SSI)</td> <td>❌ Prevented</td> <td>❌ Prevented</td> <td>❌ Prevented</td> <td>Medium</td> <td>Strict consistency</td> </tr> <tr> <td>Serializable</td> <td>❌ Prevented</td> <td>❌ Prevented</td> <td>❌ Prevented</td> <td>Low</td> <td>Critical transactions</td> </tr> </tbody> </table> <h4 id="read-uncommitted" class="position-relative d-flex align-items-center group"> Read Uncommitted <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="read-uncommitted" aria-haspopup="dialog" aria-label="Share link: Read Uncommitted"> Share link </button> </h4>Lowest isolation level, allows dirty reads: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Set isolation level BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; -- Can see uncommitted changes from other transactions MATCH (p:Person) WHERE p.age > 25 RETURN p; COMMIT; </code></pre></div>Characteristics: <ul> <li>Highest performance</li> <li>No read locks</li> <li>May read uncommitted data</li> <li>Suitable for bulk operations where dirty reads are acceptable</li> </ul> <h4 id="read-committed" class="position-relative d-flex align-items-center group"> Read Committed <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="read-committed" aria-haspopup="dialog" aria-label="Share link: Read Committed"> Share link </button> </h4>Prevents dirty reads, default for many systems: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED; -- Only see committed changes MATCH (p:Person) WHERE p.age > 25 RETURN p; -- But values may change between reads MATCH (p:Person {name: 'Alice'}) RETURN p.age; -- Result: 30 -- Another transaction commits: SET Alice.age = 31 MATCH (p:Person {name: 'Alice'}) RETURN p.age; -- Result: 31 (non-repeatable read) COMMIT; </code></pre></div>Characteristics: <ul> <li>Prevents dirty reads</li> <li>Allows non-repeatable reads</li> <li>Good balance for general queries</li> <li>Lower overhead than higher levels</li> </ul> <h4 id="repeatable-read" class="position-relative d-flex align-items-center group"> Repeatable Read <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="repeatable-read" aria-haspopup="dialog" aria-label="Share link: Repeatable Read"> Share link </button> </h4>Prevents dirty and non-repeatable reads: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ; -- First read MATCH (p:Person {name: 'Alice'}) RETURN p.age; -- Result: 30 -- Another transaction commits: SET Alice.age = 31 -- Our transaction still sees original value MATCH (p:Person {name: 'Alice'}) RETURN p.age; -- Result: 30 (repeatable read guaranteed) -- But new rows may appear (phantom reads) MATCH (p:Person) WHERE p.age > 25 RETURN count(p); -- May change as new rows inserted COMMIT; </code></pre></div>Characteristics: <ul> <li>Consistent reads within transaction</li> <li>Allows phantom reads (new rows)</li> <li>Suitable for analytical workloads</li> <li>Higher locking overhead</li> </ul> <h4 id="snapshot-isolation-default" class="position-relative d-flex align-items-center group"> Snapshot Isolation (Default) <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="snapshot-isolation-default" aria-haspopup="dialog" aria-label="Share link: Snapshot Isolation (Default)"> Share link </button> </h4>MVCC-based snapshot isolation for high concurrency: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION ISOLATION LEVEL SNAPSHOT; -- See consistent snapshot of database at transaction start MATCH (p:Person) RETURN p.name, p.age; -- Other transactions can modify data without blocking -- Our view remains consistent -- Write operations use first-committer-wins MATCH (p:Person {name: 'Alice'}) SET p.age = p.age + 1; COMMIT; </code></pre></div>Characteristics: <ul> <li>No read locks (high concurrency)</li> <li>Consistent snapshot view</li> <li>First-committer-wins for writes</li> <li>Optimal for OLTP workloads</li> <li>Default isolation level in Geode</li> </ul> Implementation: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">// Initialize snapshot isolation var isolation = try IsolationIntegration.init(allocator, mvcc_manager); defer isolation.deinit(); // Begin transaction const txn = try isolation.beginTransaction(.SnapshotIsolation, 100); // Perform reads (see snapshot) const data = try isolation.read(txn, resource_id, .SnapshotIsolation); // Commit with conflict detection try isolation.commit(txn, .SnapshotIsolation); </code></pre></div> <h4 id="serializable-snapshot-isolation-ssi" class="position-relative d-flex align-items-center group"> Serializable Snapshot Isolation (SSI) <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="serializable-snapshot-isolation-ssi" aria-haspopup="dialog" aria-label="Share link: Serializable Snapshot Isolation (SSI)"> Share link </button> </h4>Hybrid approach combining snapshot isolation with serializability: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE SNAPSHOT; -- Read-write dependencies tracked MATCH (p:Person) WHERE p.age > 30 RETURN count(p) AS older_count; -- System detects dangerous structures -- If another transaction creates serialization conflict: -- ERROR: SerializationConflict - transaction aborted -- Application should retry transaction COMMIT; </code></pre></div>Dangerous Structure Detection: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">// Dependency tracker detects RW and WR conflicts if (try dependency_tracker.checkDangerousStructure(txn.id)) { return error.SerializationConflict; } </code></pre></div>Characteristics: <ul> <li>Detects read-write (RW) and write-read (WR) dependencies</li> <li>Aborts transactions forming dangerous cycles</li> <li>Higher overhead than snapshot isolation</li> <li>Maintains serializability without full locking</li> </ul> <h4 id="serializable" class="position-relative d-flex align-items-center group"> Serializable <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="serializable" aria-haspopup="dialog" aria-label="Share link: Serializable"> Share link </button> </h4>Full serializability with phantom read prevention: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; -- Creates predicate locks to prevent phantom reads MATCH (p:Person) WHERE p.age > 30 RETURN p; -- Another transaction trying to insert Person with age=35: -- BLOCKED until our transaction commits UPDATE p:Person SET p.age = p.age + 1 WHERE p.age > 30; COMMIT; </code></pre></div>Characteristics: <ul> <li>Full ACID serializability</li> <li>Phantom read prevention via predicate locks</li> <li>Highest consistency guarantees</li> <li>Lowest concurrency (highest locking overhead)</li> <li>Suitable for critical financial transactions</li> </ul> <h3 id="phantom-read-prevention" class="position-relative d-flex align-items-center group"> Phantom Read Prevention <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="phantom-read-prevention" aria-haspopup="dialog" aria-label="Share link: Phantom Read Prevention"> Share link </button> </h3> <h4 id="predicate-locks" class="position-relative d-flex align-items-center group"> Predicate Locks <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="predicate-locks" aria-haspopup="dialog" aria-label="Share link: Predicate Locks"> Share link </button> </h4>Geode prevents phantom reads using sophisticated predicate locking: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">// Example: Range query with phantom read protection const range = PropertyRange{ .min_value = PropertyValue{ .Int = 100 }, .max_value = PropertyValue{ .Int = 200 }, .min_inclusive = true, .max_inclusive = false, }; // Acquire predicate lock try phantom_prevention.acquirePredicateLock(txn.id, "Person", "age", range); </code></pre></div>GQL Example: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; -- This query creates predicate lock on Person.age > 30 MATCH (p:Person) WHERE p.age > 30 RETURN p.name, p.age; -- Concurrent transaction trying to insert Person with age=35: -- BLOCKED by predicate lock COMMIT; -- Predicate lock released, blocked transaction can proceed </code></pre></div> <h4 id="label-based-locks" class="position-relative d-flex align-items-center group"> Label-Based Locks <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="label-based-locks" aria-haspopup="dialog" aria-label="Share link: Label-Based Locks"> Share link </button> </h4>Lock entire label to prevent structural changes: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; -- Lock all Person nodes MATCH (p:Person) RETURN count(p); -- Another transaction trying to CREATE (:Person {...}): -- BLOCKED until commit COMMIT; </code></pre></div> <h4 id="range-locks" class="position-relative d-flex align-items-center group"> Range Locks <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="range-locks" aria-haspopup="dialog" aria-label="Share link: Range Locks"> Share link </button> </h4>Protect numeric and string ranges: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Numeric range lock BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; MATCH (p:Product) WHERE p.price >= 100 AND p.price < 200 RETURN p; -- Locks price range [100, 200) COMMIT; -- String range lock BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; MATCH (u:User) WHERE u.email >= 'a@' AND u.email < 'b@' RETURN u; -- Locks email range starting with 'a' COMMIT; </code></pre></div> <h3 id="deadlock-detection-and-resolution" class="position-relative d-flex align-items-center group"> Deadlock Detection and Resolution <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="deadlock-detection-and-resolution" aria-haspopup="dialog" aria-label="Share link: Deadlock Detection and Resolution"> Share link </button> </h3> <h4 id="automatic-deadlock-detection" class="position-relative d-flex align-items-center group"> Automatic Deadlock Detection <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="automatic-deadlock-detection" aria-haspopup="dialog" aria-label="Share link: Automatic Deadlock Detection"> Share link </button> </h4>Geode implements wait-for graph cycle detection: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">// Configure deadlock detection isolation.configure( .SerializableSnapshot, true, // enable deadlock detection 500, // detection interval (ms) ); </code></pre></div>Detection Process: <ol> <li>Construct wait-for graph of blocked transactions</li> <li>Detect cycles indicating deadlocks</li> <li>Select victim based on priority</li> <li>Abort victim transaction automatically</li> <li>Log deadlock event for monitoring</li> </ol> <h4 id="priority-based-victim-selection" class="position-relative d-flex align-items-center group"> Priority-Based Victim Selection <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="priority-based-victim-selection" aria-haspopup="dialog" aria-label="Share link: Priority-Based Victim Selection"> Share link </button> </h4>Set transaction priority to influence deadlock resolution: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- High priority transaction (less likely to be victim) BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE PRIORITY 100; MATCH (account:Account {id: 'acct-123'}) SET account.balance = account.balance - 100; COMMIT; -- Low priority transaction (more likely to be victim) BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE PRIORITY 10; MATCH (account:Account {id: 'acct-456'}) SET account.balance = account.balance + 50; COMMIT; </code></pre></div>Priority Selection: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">// Set transaction priority for deadlock resolution try deadlock_detector.setPriority(txn.id, priority); // Victim selection: lowest priority transaction aborted const victim = selectVictim(cycle_transactions); </code></pre></div> <h4 id="deadlock-example" class="position-relative d-flex align-items-center group"> Deadlock Example <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="deadlock-example" aria-haspopup="dialog" aria-label="Share link: Deadlock Example"> Share link </button> </h4>Classic deadlock scenario with automatic resolution: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Transaction 1 BEGIN TRANSACTION; MATCH (a:Account {id: 'A'}) SET a.balance = a.balance - 100; -- ... waits for lock on Account B held by Transaction 2 -- Transaction 2 BEGIN TRANSACTION; MATCH (b:Account {id: 'B'}) SET b.balance = b.balance - 50; -- ... waits for lock on Account A held by Transaction 1 -- Deadlock detected after 500ms! -- Transaction 2 (lower priority) aborted automatically -- ERROR: DeadlockDetected - transaction rolled back -- Transaction 1 proceeds MATCH (b:Account {id: 'B'}) SET b.balance = b.balance + 100; COMMIT; -- Application should retry Transaction 2 </code></pre></div> <h3 id="multi-operation-transaction-patterns" class="position-relative d-flex align-items-center group"> Multi-Operation Transaction Patterns <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="multi-operation-transaction-patterns" aria-haspopup="dialog" aria-label="Share link: Multi-Operation Transaction Patterns"> Share link </button> </h3> <h4 id="batch-create-pattern" class="position-relative d-flex align-items-center group"> Batch Create Pattern <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="batch-create-pattern" aria-haspopup="dialog" aria-label="Share link: Batch Create Pattern"> Share link </button> </h4>Create multiple related entities atomically: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Create person CREATE (p:Person {name: 'Diana', age: 28, email: '[email protected]'}); -- Create address CREATE (a:Address {street: '456 Oak St', city: 'Portland', zip: '97201'}); -- Create relationships CREATE (p)-[:LIVES_AT {since: date('2024-01-15')}]->(a); -- Create phone numbers CREATE (ph1:Phone {type: 'mobile', number: '555-1111'}); CREATE (ph2:Phone {type: 'work', number: '555-2222'}); CREATE (p)-[:HAS_PHONE]->(ph1); CREATE (p)-[:HAS_PHONE]->(ph2); -- Create employment CREATE (c:Company {name: 'DataCorp', industry: 'Technology'}); CREATE (p)-[:WORKS_FOR {since: date('2022-03-01'), title: 'Engineer'}]->(c); COMMIT; </code></pre></div> <h4 id="conditional-update-pattern" class="position-relative d-flex align-items-center group"> Conditional Update Pattern <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="conditional-update-pattern" aria-haspopup="dialog" aria-label="Share link: Conditional Update Pattern"> Share link </button> </h4>Update based on current state with validation: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION ISOLATION LEVEL SERIALIZABLE; -- Read current state MATCH (product:Product {sku: 'WIDGET-123'}) RETURN product.stock AS current_stock; -- Validate sufficient stock -- If current_stock < order_quantity, ROLLBACK -- Deduct stock atomically MATCH (product:Product {sku: 'WIDGET-123'}) SET product.stock = product.stock - $order_quantity; -- Create order record CREATE (order:Order { id: $order_id, product_sku: 'WIDGET-123', quantity: $order_quantity, timestamp: timestamp() }); COMMIT; </code></pre></div> <h4 id="graph-traversal-with-modification" class="position-relative d-flex align-items-center group"> Graph Traversal with Modification <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="graph-traversal-with-modification" aria-haspopup="dialog" aria-label="Share link: Graph Traversal with Modification"> Share link </button> </h4>Traverse graph and modify along the path: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Find path from user to product MATCH path = (u:User {id: $user_id})-[:VIEWED*1..5]->(p:Product) WHERE p.category = 'Electronics' -- Update view counts along path UNWIND relationships(path) AS rel SET rel.view_count = coalesce(rel.view_count, 0) + 1; -- Update product popularity MATCH (p:Product) WHERE id(p) IN [id IN nodes(path) WHERE label(id) = 'Product'] SET p.popularity_score = p.popularity_score + 1; COMMIT; </code></pre></div> <h4 id="cascading-delete-pattern" class="position-relative d-flex align-items-center group"> Cascading Delete Pattern <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="cascading-delete-pattern" aria-haspopup="dialog" aria-label="Share link: Cascading Delete Pattern"> Share link </button> </h4>Delete node and all related entities: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Find user and all relationships MATCH (u:User {id: $user_id}) OPTIONAL MATCH (u)-[r1]-() OPTIONAL MATCH ()-[r2]->(u) -- Delete relationships first DELETE r1, r2; -- Delete related entities (addresses, phones, etc.) MATCH (u)-[:LIVES_AT]->(a:Address) DELETE a; MATCH (u)-[:HAS_PHONE]->(p:Phone) DELETE p; -- Delete user DELETE u; COMMIT; </code></pre></div> <h3 id="distributed-transactions" class="position-relative d-flex align-items-center group"> Distributed Transactions <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="distributed-transactions" aria-haspopup="dialog" aria-label="Share link: Distributed Transactions"> Share link </button> </h3> <h4 id="two-phase-commit-2pc" class="position-relative d-flex align-items-center group"> Two-Phase Commit (2PC) <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="two-phase-commit-2pc" aria-haspopup="dialog" aria-label="Share link: Two-Phase Commit (2PC)"> Share link </button> </h4>Coordinate transactions across multiple shards: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">// Begin distributed transaction const distributed_txn = try txn_coordinator.beginDistributedTransaction( participating_nodes, isolation_level ); // Execute queries within transaction const result = try coordinator.executeDistributedQuery( query, params, QueryOptions{ .transaction_id = distributed_txn.id } ); // Two-phase commit across shards try txn_coordinator.commitDistributedTransaction(distributed_txn); </code></pre></div>2PC Protocol: <ol> <li>Prepare Phase: Coordinator sends PREPARE to all participants</li> <li>Vote Collection: Wait for YES/NO votes from participants</li> <li>Commit Decision: Send COMMIT (all YES) or ABORT (any NO)</li> <li>Acknowledgment: Wait for final ACKs from participants</li> </ol> <h4 id="distributed-transaction-gql" class="position-relative d-flex align-items-center group"> Distributed Transaction GQL <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="distributed-transaction-gql" aria-haspopup="dialog" aria-label="Share link: Distributed Transaction GQL"> Share link </button> </h4>Execute distributed transactions via GQL: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Distributed transaction across shards BEGIN DISTRIBUTED TRANSACTION ISOLATION LEVEL SERIALIZABLE; -- Multi-shard operations CREATE (u:User {id: '12345', name: 'Eve', shard: 1}); CREATE (p:Product {id: '67890', name: 'Gadget', shard: 2}); CREATE (u)-[:PURCHASED {timestamp: timestamp()}]->(p); -- Two-phase commit across all participating shards COMMIT; </code></pre></div> <h4 id="distributed-isolation" class="position-relative d-flex align-items-center group"> Distributed Isolation <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="distributed-isolation" aria-haspopup="dialog" aria-label="Share link: Distributed Isolation"> Share link </button> </h4>Maintain isolation guarantees across shards: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN DISTRIBUTED TRANSACTION ISOLATION LEVEL SERIALIZABLE SNAPSHOT; -- Read from shard 1 MATCH (u:User {id: $user_id}) RETURN u.balance; -- Read from shard 2 MATCH (p:Product {id: $product_id}) RETURN p.price; -- Distributed validation: check consistency across shards -- Deduct balance on shard 1 MATCH (u:User {id: $user_id}) SET u.balance = u.balance - $product_price; -- Decrement stock on shard 2 MATCH (p:Product {id: $product_id}) SET p.stock = p.stock - 1; -- Distributed 2PC commit COMMIT; </code></pre></div> <h3 id="best-practices" class="position-relative d-flex align-items-center group"> Best Practices <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="best-practices" aria-haspopup="dialog" aria-label="Share link: Best Practices"> Share link </button> </h3> <h4 id="choose-appropriate-isolation-level" class="position-relative d-flex align-items-center group"> Choose Appropriate Isolation Level <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="choose-appropriate-isolation-level" aria-haspopup="dialog" aria-label="Share link: Choose Appropriate Isolation Level"> Share link </button> </h4>Select isolation based on workload requirements: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Analytics/reporting (allow dirty reads for performance) BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; MATCH (p:Person) RETURN avg(p.age) AS average_age; COMMIT; -- General OLTP (snapshot isolation for concurrency) BEGIN TRANSACTION ISOLATION LEVEL SNAPSHOT; MATCH (u:User {id: $id}) SET u.last_login = timestamp(); COMMIT; -- Financial transactions (serializable for consistency) BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; MATCH (from:Account {id: $from_id}), (to:Account {id: $to_id}) SET from.balance = from.balance - $amount SET to.balance = to.balance + $amount; COMMIT; </code></pre></div> <h4 id="use-savepoints-for-complex-operations" class="position-relative d-flex align-items-center group"> Use Savepoints for Complex Operations <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="use-savepoints-for-complex-operations" aria-haspopup="dialog" aria-label="Share link: Use Savepoints for Complex Operations"> Share link </button> </h4>Break complex transactions into logical units: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Step 1: Validate input MATCH (user:User {id: $user_id}) WHERE user.status = 'active' RETURN user; SAVEPOINT validation_complete; -- Step 2: Perform operation CREATE (order:Order {user_id: $user_id, items: $items}); SAVEPOINT order_created; -- Step 3: Update inventory MATCH (product:Product) WHERE product.id IN $product_ids SET product.stock = product.stock - 1; SAVEPOINT inventory_updated; -- If any step fails, rollback to previous savepoint -- ROLLBACK TO validation_complete; COMMIT; </code></pre></div> <h4 id="minimize-transaction-duration" class="position-relative d-flex align-items-center group"> Minimize Transaction Duration <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="minimize-transaction-duration" aria-haspopup="dialog" aria-label="Share link: Minimize Transaction Duration"> Share link </button> </h4>Keep transactions short to reduce lock contention: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- ❌ Bad: Long transaction holding locks START TRANSACTION; MATCH (p:Person) RETURN p; -- Long query -- ... application logic taking 10 seconds ... CREATE (n:Node {data: $result}); COMMIT; -- ✅ Good: Short transaction -- Do expensive computation outside transaction -- Application logic computes result first START TRANSACTION; CREATE (n:Node {data: $result}); -- Quick insert COMMIT; </code></pre></div> <h4 id="retry-on-serialization-conflicts" class="position-relative d-flex align-items-center group"> Retry on Serialization Conflicts <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="retry-on-serialization-conflicts" aria-haspopup="dialog" aria-label="Share link: Retry on Serialization Conflicts"> Share link </button> </h4>Implement retry logic for transient conflicts: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-python" data-lang="python"># Python client example max_retries = 3 for attempt in range(max_retries): try: conn.execute("BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE SNAPSHOT") conn.execute("MATCH (a:Account {id: $id}) SET a.balance = a.balance - $amount", params) conn.execute("COMMIT") break # Success except SerializationConflict: if attempt == max_retries - 1: raise # Max retries exceeded time.sleep(0.1 * (2 ** attempt)) # Exponential backoff continue </code></pre></div> <h4 id="monitor-transaction-metrics" class="position-relative d-flex align-items-center group"> Monitor Transaction Metrics <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="monitor-transaction-metrics" aria-haspopup="dialog" aria-label="Share link: Monitor Transaction Metrics"> Share link </button> </h4>Track transaction statistics for optimization: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">// Get isolation statistics const stats = isolation.getStatistics(); const phantom_stats = isolation.getPhantomReadStatistics(); // Monitor key metrics: // - Total transactions // - Serialization conflicts // - Deadlocks detected // - Phantom read conflicts // - Average transaction duration </code></pre></div> <h3 id="error-handling" class="position-relative d-flex align-items-center group"> Error Handling <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="error-handling" aria-haspopup="dialog" aria-label="Share link: Error Handling"> Share link </button> </h3> <h4 id="transaction-error-types" class="position-relative d-flex align-items-center group"> Transaction Error Types <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="transaction-error-types" aria-haspopup="dialog" aria-label="Share link: Transaction Error Types"> Share link </button> </h4>Comprehensive error handling for transaction conflicts: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">pub const TransactionError = error{ SerializationConflict, // SSI dangerous structure PhantomReadConflict, // Phantom read blocked DeadlockDetected, // Deadlock cycle found TimeoutExpired, // Transaction timeout ConflictDetected, // General conflict TransactionAlreadyActive, // START TRANSACTION when active NoActiveTransaction, // COMMIT/ROLLBACK without transaction }; </code></pre></div> <h4 id="error-resolution-strategies" class="position-relative d-flex align-items-center group"> Error Resolution Strategies <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="error-resolution-strategies" aria-haspopup="dialog" aria-label="Share link: Error Resolution Strategies"> Share link </button> </h4>Handle common transaction errors: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Serialization Conflict -- ERROR: SerializationConflict - dangerous structure detected -- RESOLUTION: Retry transaction with exponential backoff -- Phantom Read Conflict -- ERROR: PhantomReadConflict - predicate lock conflict -- RESOLUTION: Change query pattern or use lower isolation level -- Deadlock Detected -- ERROR: DeadlockDetected - transaction aborted as victim -- RESOLUTION: Retry transaction, consider changing lock order -- Timeout Expired -- ERROR: TimeoutExpired - transaction exceeded timeout -- RESOLUTION: Optimize query performance or increase timeout -- Transaction Already Active -- ERROR: TransactionAlreadyActive -- RESOLUTION: COMMIT or ROLLBACK current transaction first -- No Active Transaction -- ERROR: NoActiveTransaction -- RESOLUTION: START TRANSACTION before COMMIT/ROLLBACK </code></pre></div> <h3 id="configuration" class="position-relative d-flex align-items-center group"> Configuration <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="configuration" aria-haspopup="dialog" aria-label="Share link: Configuration"> Share link </button> </h3> <h4 id="environment-variables" class="position-relative d-flex align-items-center group"> Environment Variables <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="environment-variables" aria-haspopup="dialog" aria-label="Share link: Environment Variables"> Share link </button> </h4>Configure transaction behavior: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"># Default isolation level export GEODE_DEFAULT_ISOLATION=SNAPSHOT_ISOLATION # Deadlock detection export GEODE_DEADLOCK_DETECTION_ENABLED=true export GEODE_DEADLOCK_DETECTION_INTERVAL_MS=1000 # Transaction timeouts export GEODE_TRANSACTION_TIMEOUT_MS=30000 # Phantom read prevention export GEODE_PHANTOM_READ_PREVENTION=true export GEODE_PREDICATE_LOCK_TIMEOUT_MS=5000 </code></pre></div> <h4 id="server-configuration" class="position-relative d-flex align-items-center group"> Server Configuration <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="server-configuration" aria-haspopup="dialog" aria-label="Share link: Server Configuration"> Share link </button> </h4>Configure via YAML: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-yaml" data-lang="yaml">transactions: default_isolation: SNAPSHOT_ISOLATION deadlock_detection: enabled: true interval_ms: 1000 timeout_ms: 30000 phantom_prevention: enabled: true lock_timeout_ms: 5000 </code></pre></div> <h3 id="performance-characteristics" class="position-relative d-flex align-items-center group"> Performance Characteristics <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="performance-characteristics" aria-haspopup="dialog" aria-label="Share link: Performance Characteristics"> Share link </button> </h3> <h4 id="isolation-level-overhead" class="position-relative d-flex align-items-center group"> Isolation Level Overhead <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="isolation-level-overhead" aria-haspopup="dialog" aria-label="Share link: Isolation Level Overhead"> Share link </button> </h4>Empirical overhead for different isolation levels: <table> <thead> <tr> <th>Isolation Level</th> <th>Read Overhead</th> <th>Write Overhead</th> <th>Conflict Rate</th> <th>Lock Duration</th> </tr> </thead> <tbody> <tr> <td>Read Uncommitted</td> <td>0μs</td> <td>0μs</td> <td>0%</td> <td>None</td> </tr> <tr> <td>Read Committed</td> <td>5-10μs</td> <td>10-20μs</td> <td><1%</td> <td>Short</td> </tr> <tr> <td>Repeatable Read</td> <td>10-30μs</td> <td>20-50μs</td> <td>1-5%</td> <td>Medium</td> </tr> <tr> <td>Snapshot Isolation</td> <td>10-50μs</td> <td>20-80μs</td> <td><2%</td> <td>None (readers)</td> </tr> <tr> <td>Serializable Snapshot</td> <td>20-100μs</td> <td>50-150μs</td> <td>3-10%</td> <td>Medium</td> </tr> <tr> <td>Serializable</td> <td>50-200μs</td> <td>100-500μs</td> <td>5-20%</td> <td>Long</td> </tr> </tbody> </table> <h4 id="memory-usage" class="position-relative d-flex align-items-center group"> Memory Usage <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="memory-usage" aria-haspopup="dialog" aria-label="Share link: Memory Usage"> Share link </button> </h4>Transaction system memory overhead: <ul> <li>Dependency Tracker: ~50-200 bytes per active transaction</li> <li>Deadlock Detector: ~100-500 bytes per active transaction</li> <li>Predicate Locks: ~200-1000 bytes per lock</li> <li>Total Overhead: ~350-1700 bytes per active transaction</li> </ul> <h3 id="related-documentation" class="position-relative d-flex align-items-center group"> Related Documentation <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="related-documentation" aria-haspopup="dialog" aria-label="Share link: Related Documentation"> Share link </button> </h3><ul> <li><a href="/docs/architecture/distributed-architecture/" >Distributed Architecture</a> - Distributed transaction coordination</li> <li><a href="/docs/query/performance-tuning/" >Query Performance Tuning</a> - Optimize transaction performance</li> <li><a href="/docs/guides/troubleshooting/" >Troubleshooting Guide</a> - Common transaction issues</li> <li><a href="/docs/configuration/server-configuration/" >Server Configuration</a> - Transaction configuration options</li> </ul> <h3 id="summary" class="position-relative d-flex align-items-center group"> Summary <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="summary" aria-haspopup="dialog" aria-label="Share link: Summary"> Share link </button> </h3>Geode provides enterprise-grade transaction management: <ul> <li>Six Isolation Levels: Read Uncommitted, Read Committed, Repeatable Read, Snapshot Isolation, Serializable Snapshot, Serializable</li> <li>Savepoint Support: Partial rollback within transactions</li> <li>Phantom Read Prevention: Predicate locking system</li> <li>Deadlock Detection: Priority-based automatic resolution</li> <li>Distributed Transactions: Two-phase commit across shards</li> <li>MVCC Implementation: High-concurrency snapshot isolation</li> <li>SSI Support: Serializable snapshot isolation with dependency tracking</li> </ul> Choose the appropriate isolation level based on consistency requirements and performance needs. Use savepoints for complex multi-step operations. Monitor transaction metrics to identify performance bottlenecks and optimize accordingly.