Transactions and Data Integrity

<h2 id="transactions-and-data-integrity" class="position-relative d-flex align-items-center group"> Transactions and Data Integrity <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="transactions-and-data-integrity" aria-haspopup="dialog" aria-label="Share link: Transactions and Data Integrity"> Share link </button> </h2><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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'fa-duotone fa-clipboard-check':'fa-duotone fa-circle-exclamation'; setTimeout(()=>{ icon.className=prev; },1800); } function handleShareClick(e){ e.preventDefault(); const btn=e.currentTarget; const id=btn.getAttribute('data-share-target'); if(id) openModal(id); } function bindShareButtons(){ document.querySelectorAll('.h-share').forEach(btn=>{ if(!btn.dataset.hShareBound){ btn.addEventListener('click', handleShareClick); btn.dataset.hShareBound='1'; } }); } bindShareButtons(); if(document.readyState==='loading'){ document.addEventListener('DOMContentLoaded', bindShareButtons); } else { requestAnimationFrame(bindShareButtons); } document.addEventListener('click', function(e){ const shareBtn=e.target.closest && e.target.closest('.h-share'); if(shareBtn && !shareBtn.dataset.hShareBound){ handleShareClick.call(shareBtn, e); } }, true); document.addEventListener('click', e=>{ if(e.target===modal) closeModal(); if(e.target.closest && e.target.closest('.hsm-close')){ e.preventDefault(); closeModal(); } 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>Geode provides true ACID transactions with MVCC (Multi-Version Concurrency Control) and SSI (Serializable Snapshot Isolation) for the strongest consistency guarantees. <h3 id="transaction-basics" class="position-relative d-flex align-items-center group"> Transaction Basics <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-basics" aria-haspopup="dialog" aria-label="Share link: Transaction Basics"> Share link </button> </h3>From <code>TRANSACTION_MANAGEMENT.md</code>: <h4 id="starting-transactions" class="position-relative d-flex align-items-center group"> Starting 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="starting-transactions" aria-haspopup="dialog" aria-label="Share link: Starting Transactions"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Explicit transaction START TRANSACTION; -- Make changes CREATE (:Person {name: "Alice", age: 30}); CREATE (:Person {name: "Bob", age: 25}); -- Commit changes COMMIT; </code></pre></div>Auto-commit mode: Single statements outside a transaction are auto-committed. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- This is auto-committed CREATE (:Person {name: "Charlie", age: 35}); </code></pre></div> <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><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; CREATE (:Person {name: "Alice", age: 30}); -- Oops, error or need to undo ROLLBACK; -- All changes since START TRANSACTION are undone </code></pre></div> <h4 id="savepoints-extension" class="position-relative d-flex align-items-center group"> Savepoints (Extension) <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-extension" aria-haspopup="dialog" aria-label="Share link: Savepoints (Extension)"> Share link </button> </h4>Savepoints allow partial rollback within a transaction: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Checkpoint 1 CREATE (:Person {name: "Alice", age: 30}); SAVEPOINT sp1; -- Checkpoint 2 CREATE (:Person {name: "Bob", age: 25}); SAVEPOINT sp2; -- Checkpoint 3 CREATE (:Person {name: "Charlie", age: 35}); -- Rollback to sp2 (undoes Charlie, keeps Alice and Bob) ROLLBACK TO SAVEPOINT sp2; -- Rollback to sp1 (undoes Bob and Charlie, keeps Alice) ROLLBACK TO SAVEPOINT sp1; COMMIT; </code></pre></div>Use cases: <ul> <li>Error recovery within complex transactions</li> <li>Partial rollback without losing all work</li> <li>Implementing application-level “undo” functionality</li> </ul> <h3 id="acid-semantics" class="position-relative d-flex align-items-center group"> ACID Semantics <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="acid-semantics" aria-haspopup="dialog" aria-label="Share link: ACID Semantics"> Share link </button> </h3>Geode guarantees ACID properties: <h4 id="atomicity" class="position-relative d-flex align-items-center group"> Atomicity <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="atomicity" aria-haspopup="dialog" aria-label="Share link: Atomicity"> Share link </button> </h4>All-or-nothing: Either all operations in a transaction succeed, or none do. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; CREATE (:Account {id: 1, balance: 1000}); CREATE (:Account {id: 2, balance: 500}); -- Transfer $100: debit from 1, credit to 2 MATCH (a1:Account {id: 1}) SET a1.balance = a1.balance - 100; MATCH (a2:Account {id: 2}) SET a2.balance = a2.balance + 100; -- If any statement fails, ALL are rolled back COMMIT; </code></pre></div>Failure scenarios: <ul> <li>Constraint violation → entire transaction rolled back</li> <li>Disk I/O error → transaction rolled back</li> <li>Server crash during transaction → WAL replay recovers consistent state</li> </ul> <h4 id="consistency" class="position-relative d-flex align-items-center group"> Consistency <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="consistency" aria-haspopup="dialog" aria-label="Share link: Consistency"> Share link </button> </h4>Integrity constraints are maintained: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Constraint: account balance must be non-negative CREATE CONSTRAINT positive_balance ON Account(balance) CHECK (balance >= 0); START TRANSACTION; MATCH (a:Account {id: 1}) SET a.balance = a.balance - 2000; -- Would make balance negative -- Transaction fails with constraint violation COMMIT; -- Returns error, no changes applied </code></pre></div> <h4 id="isolation" class="position-relative d-flex align-items-center group"> 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="isolation" aria-haspopup="dialog" aria-label="Share link: Isolation"> Share link </button> </h4>Isolation level: Serializable Snapshot Isolation (SSI) What this means: <ul> <li>Transactions see a consistent snapshot of the database</li> <li>Concurrent transactions are serializable (equivalent to some serial execution)</li> <li>No dirty reads, no non-repeatable reads, no phantom reads</li> </ul> Example: No dirty reads: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Transaction 1 (T1) START TRANSACTION; CREATE (:Person {name: "Alice", age: 30}); -- Not yet committed -- Transaction 2 (T2, concurrent) START TRANSACTION; MATCH (p:Person {name: "Alice"}) RETURN p; -- Returns nothing (Alice not visible until T1 commits) COMMIT; -- T1 commits COMMIT; -- Now T2 would see Alice START TRANSACTION; MATCH (p:Person {name: "Alice"}) RETURN p; -- Returns Alice COMMIT; </code></pre></div>See Isolation Model section below for MVCC + SSI details. <h4 id="durability" class="position-relative d-flex align-items-center group"> Durability <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="durability" aria-haspopup="dialog" aria-label="Share link: Durability"> Share link </button> </h4>Write-Ahead Logging (WAL) ensures committed transactions survive crashes. Guarantee: Once <code>COMMIT</code> returns success, changes are durable (written to WAL on disk). Recovery: <ul> <li>On startup, Geode replays WAL to recover committed transactions</li> <li>Uncommitted transactions are rolled back</li> </ul> <h3 id="isolation-model-mvcc--ssi" class="position-relative d-flex align-items-center group"> Isolation Model: MVCC + 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="isolation-model-mvcc--ssi" aria-haspopup="dialog" aria-label="Share link: Isolation Model: MVCC &#43; SSI"> Share link </button> </h3>From <code>ENHANCED_TRANSACTION_ISOLATION.md</code>: <h4 id="multi-version-concurrency-control-mvcc" class="position-relative d-flex align-items-center group"> Multi-Version Concurrency Control (MVCC) <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-version-concurrency-control-mvcc" aria-haspopup="dialog" aria-label="Share link: Multi-Version Concurrency Control (MVCC)"> Share link </button> </h4>MVCC maintains multiple versions of data to allow concurrent readers and writers. How it works: <ol> <li>Each transaction sees a snapshot of the database at transaction start</li> <li>Writes create new versions without blocking readers</li> <li>Readers see old versions until writers commit</li> <li>Old versions are garbage-collected after all transactions complete</li> </ol> Example: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback">Time | T1 (Read) | T2 (Write) ------|------------------------------|---------------------------- t0 | START TRANSACTION | t1 | | START TRANSACTION t2 | MATCH (p:Person {id: 1}) | | RETURN p.age; -- Returns 30 | t3 | | MATCH (p:Person {id: 1}) | | SET p.age = 31; t4 | MATCH (p:Person {id: 1}) | | RETURN p.age; -- Still 30! | t5 | | COMMIT; t6 | MATCH (p:Person {id: 1}) | | RETURN p.age; -- Still 30! | t7 | COMMIT; | t8 | START TRANSACTION | t9 | MATCH (p:Person {id: 1}) | | RETURN p.age; -- Now 31 | </code></pre></div>Benefit: Readers never block writers, writers never block readers. <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>SSI prevents anomalies by detecting conflicts between concurrent transactions. Conflict types: <ul> <li>Read-Write conflict: T1 reads X, T2 modifies X</li> <li>Write-Write conflict: T1 modifies X, T2 modifies X</li> <li>Dependency cycle: T1 → T2 → T3 → T1 (serialization impossible)</li> </ul> Example: Write skew prevention: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Initial state: Alice balance = 1000, Bob balance = 1000 -- T1: Transfer $800 from Alice to Charlie START TRANSACTION; MATCH (a:Account {name: "Alice"}) WHERE a.balance >= 800 -- Check passes (balance = 1000) SET a.balance = a.balance - 800; -- T1 pauses here -- T2: Transfer $800 from Alice to Diana (concurrent) START TRANSACTION; MATCH (a:Account {name: "Alice"}) WHERE a.balance >= 800 -- Check passes (sees snapshot with balance = 1000) SET a.balance = a.balance - 800; COMMIT; -- T2 commits first -- T1 resumes COMMIT; -- FAILS with serialization error (conflict detected) </code></pre></div>SSI detects that T1 and T2 both read Alice’s balance and would cause inconsistency if both committed. Application handling: Retry failed transactions with exponential backoff. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-python" data-lang="python"># Python client example import asyncio from geode_client import QueryError max_retries = 3 for attempt in range(max_retries): async with client.connection() as conn: await conn.begin() try: await conn.execute( "MATCH (a:Account {name: 'Alice'}) SET a.balance = a.balance - 800" ) await conn.execute( "MATCH (c:Account {name: 'Charlie'}) SET c.balance = c.balance + 800" ) await conn.commit() break # Success except QueryError: await conn.rollback() if attempt == max_retries - 1: raise # Final attempt failed await asyncio.sleep(2 ** attempt) # Exponential backoff </code></pre></div> <h3 id="sessions-and-transaction-scope" class="position-relative d-flex align-items-center group"> Sessions and Transaction Scope <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="sessions-and-transaction-scope" aria-haspopup="dialog" aria-label="Share link: Sessions and Transaction Scope"> Share link </button> </h3>From <code>SESSION_MANAGEMENT.md</code>: Sessions maintain state across multiple requests: <ul> <li>Current graph: Selected with <code>USE <graph></code></li> <li>Transaction state: Active transaction, savepoints</li> <li>Prepared statements: Cached query plans</li> <li>Session variables: User-defined variables (future)</li> </ul> Session lifetime: <ul> <li>Created on first connection</li> <li>Persists across queries until disconnected</li> <li>Automatically cleaned up on disconnect or timeout</li> </ul> Example: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Session 1 USE SocialNetwork; -- Set graph context START TRANSACTION; CREATE (:Person {name: "Alice", age: 30}); -- Transaction is in-progress -- Another query in same session CREATE (:Person {name: "Bob", age: 25}); -- Added to same transaction COMMIT; -- Both Alice and Bob committed atomically -- Session 2 (different connection) USE CompanyGraph; -- Different graph context -- Alice and Bob are not visible here (different graph) </code></pre></div>Session isolation: Each session has independent transaction state. <h3 id="write-ahead-logging-wal-and-recovery" class="position-relative d-flex align-items-center group"> Write-Ahead Logging (WAL) and Recovery <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="write-ahead-logging-wal-and-recovery" aria-haspopup="dialog" aria-label="Share link: Write-Ahead Logging (WAL) and Recovery"> Share link </button> </h3>From <code>SERVER_FEATURES.md</code>: <h4 id="wal-architecture" class="position-relative d-flex align-items-center group"> WAL Architecture <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="wal-architecture" aria-haspopup="dialog" aria-label="Share link: WAL Architecture"> Share link </button> </h4>Write-Ahead Log ensures durability: <ol> <li>Before modifying data pages, write changes to WAL</li> <li>WAL writes are sequential (fast, no random I/O)</li> <li>WAL is fsync’d to disk before returning commit success</li> <li>Data pages are written asynchronously (in background)</li> </ol> WAL entry format: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback">[LSN | Transaction ID | Operation | Old Value | New Value | Checksum] </code></pre></div><ul> <li>LSN: Log Sequence Number (monotonic)</li> <li>Transaction ID: Unique transaction identifier</li> <li>Operation: INSERT/UPDATE/DELETE</li> <li>Old Value: For undo (rollback)</li> <li>New Value: For redo (recovery)</li> <li>Checksum: Detect corruption</li> </ul> <h4 id="recovery-process" class="position-relative d-flex align-items-center group"> Recovery Process <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="recovery-process" aria-haspopup="dialog" aria-label="Share link: Recovery Process"> Share link </button> </h4>On startup (after crash): <ol> <li>Read WAL from last checkpoint</li> <li>Redo phase: Replay committed transactions (apply changes)</li> <li>Undo phase: Roll back uncommitted transactions</li> <li>Checkpoint: Write all dirty pages to disk, truncate WAL</li> </ol> Example timeline: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback">t0: Checkpoint (all pages on disk) t1: T1 START t2: T1 INSERT (:Person {name: "Alice"}) t3: T1 COMMIT (WAL entry written) t4: T2 START t5: T2 INSERT (:Person {name: "Bob"}) t6: CRASH (T2 not committed) -- Recovery t7: Startup t8: Replay WAL: - T1 committed → REDO (Alice inserted) - T2 not committed → UNDO (Bob not inserted) t9: Recovery complete (Alice visible, Bob not) </code></pre></div> <h4 id="point-in-time-recovery-pitr" class="position-relative d-flex align-items-center group"> Point-in-Time Recovery (PITR) <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="point-in-time-recovery-pitr" aria-haspopup="dialog" aria-label="Share link: Point-in-Time Recovery (PITR)"> Share link </button> </h4>Restore to specific timestamp: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"># Restore from backup + replay WAL to timestamp geode restore \ --from s3://backups/geode-2024-01-15.tar.gz \ --wal-dir /var/lib/geode/wal \ --until "2024-01-15T14:30:00Z" </code></pre></div>Use cases: <ul> <li>Recover from accidental data deletion</li> <li>Audit historical state</li> <li>Clone database at specific point</li> </ul> See also: <a href="/docs/ops/deployment#backups" >Deployment Guide</a> for backup/restore procedures <h3 id="storage-checksums-and-integrity" class="position-relative d-flex align-items-center group"> Storage Checksums and Integrity <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="storage-checksums-and-integrity" aria-haspopup="dialog" aria-label="Share link: Storage Checksums and Integrity"> Share link </button> </h3>From <code>SERVER_FEATURES.md</code>: Checksums detect data corruption: <ul> <li>Page-level checksums: Each data page has CRC32 checksum</li> <li>WAL checksums: Each WAL entry has checksum</li> <li>Verification: On read, checksum is validated</li> <li>Corruption handling: If checksum fails, return error (do not return corrupt data)</li> </ul> Example error: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback">ERROR: page checksum verification failed DETAIL: Expected checksum 0x12345678, found 0xabcdef00 HINT: This may indicate disk corruption. Restore from backup. </code></pre></div> <h3 id="constraints-and-integrity-current-status" class="position-relative d-flex align-items-center group"> Constraints and Integrity (Current Status) <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="constraints-and-integrity-current-status" aria-haspopup="dialog" aria-label="Share link: Constraints and Integrity (Current Status)"> Share link </button> </h3>Implemented: <ul> <li><code>UNIQUE</code> - Unique constraint on property</li> <li><code>NOT NULL</code> - Property must have value</li> <li><code>CHECK</code> - Custom predicate constraint</li> </ul> Example: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Unique email CREATE CONSTRAINT unique_email ON User(email) ASSERT UNIQUE; -- Not null name CREATE CONSTRAINT name_required ON Person(name) ASSERT NOT NULL; -- Check constraint (balance >= 0) CREATE CONSTRAINT positive_balance ON Account(balance) CHECK (balance >= 0); </code></pre></div>Planned (per ISO standard): <ul> <li>Foreign key constraints (relationship cardinality)</li> <li>Pattern constraints (e.g., “Person must have at least one EMAIL relationship”)</li> <li>Existence constraints (e.g., “Person must have ‘age’ property”)</li> </ul> <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="1-keep-transactions-short" class="position-relative d-flex align-items-center group"> 1. Keep Transactions Short <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="1-keep-transactions-short" aria-haspopup="dialog" aria-label="Share link: 1. Keep Transactions Short"> Share link </button> </h4>Good (fast commit): <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; MATCH (a:Account {id: 1}) SET a.balance = a.balance - 100; COMMIT; </code></pre></div>Bad (long-running transaction blocks others): <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Complex analytics query taking 30 seconds MATCH (p:Person)-[:KNOWS*]->(friend) RETURN COUNT(friend); -- Locks held for 30 seconds COMMIT; </code></pre></div>Tip: Use read-only queries outside transactions for analytics. <h4 id="2-retry-on-serialization-errors" class="position-relative d-flex align-items-center group"> 2. Retry on Serialization Errors <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="2-retry-on-serialization-errors" aria-haspopup="dialog" aria-label="Share link: 2. Retry on Serialization Errors"> Share link </button> </h4>SSI may abort transactions due to conflicts. Retry with exponential backoff. <div class="docs-tabs mb-4"> <ul class="nav nav-tabs" id="tabs-1774880882602762826" role="tablist"><li class="nav-item" role="presentation"> <button class="nav-link active" id="tabs-1774880882602762826-tab-0-tab" data-bs-toggle="tab" data-bs-target="#tabs-1774880882602762826-tab-0" type="button" role="tab" aria-controls="tabs-1774880882602762826-tab-0" aria-selected="true" > Go </button> </li><li class="nav-item" role="presentation"> <button class="nav-link" id="tabs-1774880882602762826-tab-1-tab" data-bs-toggle="tab" data-bs-target="#tabs-1774880882602762826-tab-1" type="button" role="tab" aria-controls="tabs-1774880882602762826-tab-1" aria-selected="false" > Python </button> </li><li class="nav-item" role="presentation"> <button class="nav-link" id="tabs-1774880882602762826-tab-2-tab" data-bs-toggle="tab" data-bs-target="#tabs-1774880882602762826-tab-2" type="button" role="tab" aria-controls="tabs-1774880882602762826-tab-2" aria-selected="false" > Rust </button> </li><li class="nav-item" role="presentation"> <button class="nav-link" id="tabs-1774880882602762826-tab-3-tab" data-bs-toggle="tab" data-bs-target="#tabs-1774880882602762826-tab-3" type="button" role="tab" aria-controls="tabs-1774880882602762826-tab-3" aria-selected="false" > Node.js </button> </li><li class="nav-item" role="presentation"> <button class="nav-link" id="tabs-1774880882602762826-tab-4-tab" data-bs-toggle="tab" data-bs-target="#tabs-1774880882602762826-tab-4" type="button" role="tab" aria-controls="tabs-1774880882602762826-tab-4" aria-selected="false" > Zig </button> </li></ul> <div class="tab-content border border-top-0 rounded-bottom p-3" id="tabs-1774880882602762826-content"><div class="tab-pane fade show active" id="tabs-1774880882602762826-tab-0" role="tabpanel" aria-labelledby="tabs-1774880882602762826-tab-0-tab" > <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-go" data-lang="go">func transferMoney(ctx context.Context, db *sql.DB, fromID, toID string, amount int) error { for attempt := 0; attempt < maxRetries; attempt++ { tx, err := db.BeginTx(ctx, nil) if err != nil { return err } _, err = tx.ExecContext(ctx, "MATCH (a:Account {id: ?}) SET a.balance = a.balance - ?", fromID, amount) if err != nil { tx.Rollback() if isSerializationError(err) && attempt < maxRetries-1 { time.Sleep(time.Duration(1<<attempt) * 100 * time.Millisecond) continue } return err } _, err = tx.ExecContext(ctx, "MATCH (b:Account {id: ?}) SET b.balance = b.balance + ?", toID, amount) if err != nil { tx.Rollback() if isSerializationError(err) && attempt < maxRetries-1 { time.Sleep(time.Duration(1<<attempt) * 100 * time.Millisecond) continue } return err } return tx.Commit() } return fmt.Errorf("max retries exceeded") } </code></pre></div> </div><div class="tab-pane fade" id="tabs-1774880882602762826-tab-1" role="tabpanel" aria-labelledby="tabs-1774880882602762826-tab-1-tab" > <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-python" data-lang="python">async def transfer_money(client, from_id, to_id, amount): for attempt in range(MAX_RETRIES): async with client.connection() as conn: await conn.begin() try: await conn.execute( "MATCH (a:Account {id: $id}) SET a.balance = a.balance - $amount", {"id": from_id, "amount": amount}, ) await conn.execute( "MATCH (b:Account {id: $id}) SET b.balance = b.balance + $amount", {"id": to_id, "amount": amount}, ) await conn.commit() return # Success except QueryError: await conn.rollback() if attempt == MAX_RETRIES - 1: raise await asyncio.sleep(2 ** attempt) </code></pre></div> </div><div class="tab-pane fade" id="tabs-1774880882602762826-tab-2" role="tabpanel" aria-labelledby="tabs-1774880882602762826-tab-2-tab" > <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-rust" data-lang="rust">async fn transfer_money(conn: &mut Connection, from_id: &str, to_id: &str, amount: i64) -> Result<()> { for attempt in 0..MAX_RETRIES { conn.begin().await?; let debit_params = [ ("id", Value::string(from_id)), ("amount", Value::int(amount)), ].into(); let credit_params = [ ("id", Value::string(to_id)), ("amount", Value::int(amount)), ].into(); match async { conn.query_with_params( "MATCH (a:Account {id: $id}) SET a.balance = a.balance - $amount", &debit_params ).await?; conn.query_with_params( "MATCH (b:Account {id: $id}) SET b.balance = b.balance + $amount", &credit_params ).await?; conn.commit().await }.await { Ok(_) => return Ok(()), Err(e) if e.is_retryable() && attempt < MAX_RETRIES - 1 => { conn.rollback().await?; tokio::time::sleep(Duration::from_millis(100 * (1 << attempt))).await; } Err(e) => { conn.rollback().await?; return Err(e); } } } Err("max retries exceeded".into()) } </code></pre></div> </div><div class="tab-pane fade" id="tabs-1774880882602762826-tab-3" role="tabpanel" aria-labelledby="tabs-1774880882602762826-tab-3-tab" > <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-typescript" data-lang="typescript">async function transferMoney(fromId: string, toId: string, amount: number) { for (let attempt = 0; attempt < MAX_RETRIES; attempt++) { const conn = await client.getConnection(); const tx = await conn.begin(); try { await tx.exec( 'MATCH (a:Account {id: $id}) SET a.balance = a.balance - $amount', { params: { id: fromId, amount } } ); await tx.exec( 'MATCH (b:Account {id: $id}) SET b.balance = b.balance + $amount', { params: { id: toId, amount } } ); await tx.commit(); return; // Success } catch (e) { await tx.rollback(); if (isRetryableError(e) && attempt < MAX_RETRIES - 1) { await new Promise(r => setTimeout(r, 100 * (1 << attempt))); continue; } throw e; } finally { await client.releaseConnection(conn); } } } </code></pre></div> </div><div class="tab-pane fade" id="tabs-1774880882602762826-tab-4" role="tabpanel" aria-labelledby="tabs-1774880882602762826-tab-4-tab" > <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-zig" data-lang="zig">fn transferMoney(client: *GeodeClient, allocator: std.mem.Allocator, from_id: []const u8, to_id: []const u8, amount: i64) !void { var attempt: usize = 0; while (attempt < MAX_RETRIES) : (attempt += 1) { try client.sendBegin(); _ = try client.receiveMessage(30000); // Build params for parameterized queries var params = std.json.ObjectMap.init(allocator); defer params.deinit(); try params.put("from_id", .{ .string = from_id }); try params.put("to_id", .{ .string = to_id }); try params.put("amount", .{ .integer = amount }); // Debit sender client.sendRunGql(1, "MATCH (a:Account {id: $from_id}) SET a.balance = a.balance - $amount", .{ .object = params }) catch |err| { client.sendRollback() catch {}; _ = client.receiveMessage(30000) catch {}; if (err == error.SerializationError and attempt < MAX_RETRIES - 1) { std.time.sleep(100_000_000 * (@as(u64, 1) << @intCast(attempt))); continue; } return err; }; _ = try client.receiveMessage(30000); // Credit receiver try client.sendRunGql(2, "MATCH (a:Account {id: $to_id}) SET a.balance = a.balance + $amount", .{ .object = params }); _ = try client.receiveMessage(30000); try client.sendCommit(); _ = try client.receiveMessage(30000); return; } return error.MaxRetriesExceeded; } </code></pre></div> </div></div> </div> <h4 id="3-use-savepoints-for-complex-logic" class="position-relative d-flex align-items-center group"> 3. Use Savepoints for Complex Logic <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="3-use-savepoints-for-complex-logic" aria-haspopup="dialog" aria-label="Share link: 3. Use Savepoints for Complex Logic"> Share link </button> </h4>Break complex transactions into logical steps with savepoints: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">START TRANSACTION; -- Step 1: Validate input SAVEPOINT validate; MATCH (a:Account {id: 1}) WHERE a.balance >= 100 RETURN a; -- Ensure sufficient balance -- Step 2: Debit SAVEPOINT debit; MATCH (a:Account {id: 1}) SET a.balance = a.balance - 100; -- Step 3: Credit MATCH (b:Account {id: 2}) SET b.balance = b.balance + 100; -- If step 3 fails, can rollback to 'debit' and retry -- ROLLBACK TO SAVEPOINT debit; COMMIT; </code></pre></div> <h4 id="4-monitor-transaction-metrics" class="position-relative d-flex align-items-center group"> 4. 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="4-monitor-transaction-metrics" aria-haspopup="dialog" aria-label="Share link: 4. Monitor Transaction Metrics"> Share link </button> </h4>Key metrics (from Prometheus): <ul> <li><code>geode_transactions_active</code> - Active transactions (should be low)</li> <li><code>geode_transactions_committed</code> - Successful commits</li> <li><code>geode_transactions_aborted</code> - Serialization errors (retry rate)</li> <li><code>geode_wal_writes_bytes</code> - WAL write throughput</li> </ul> See: <a href="/docs/ops/observability" >Monitoring and Telemetry</a> for metrics setup <h3 id="next-steps" class="position-relative d-flex align-items-center group"> Next Steps <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="next-steps" aria-haspopup="dialog" aria-label="Share link: Next Steps"> Share link </button> </h3><ul> <li><a href="/docs/gql/guide" >GQL Guide</a> - Transaction syntax and examples</li> <li><a href="/docs/security/overview" >Security Guide</a> - Audit logging and integrity</li> <li><a href="/docs/ops/deployment" >Deployment Guide</a> - Backup and recovery procedures</li> <li><a href="/docs/transactions/advanced-patterns/" >Enhanced Transaction Isolation</a> - Deep dive into MVCC + SSI</li> <li><a href="/docs/security/session-management/" >Session Management</a> - Session lifecycle and state</li> </ul>