GQL Reference Documentation

Complete reference documentation for GQL (Graph Query Language), the ISO/IEC 39075:2024 standard language for graph databases. This guide covers all GQL syntax, clauses, expressions, functions, and advanced features as implemented in Geode. <h3 id="what-is-gql" class="position-relative d-flex align-items-center group"> What is 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="what-is-gql" aria-haspopup="dialog" aria-label="Share link: What is GQL?"> 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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overflow: hidden; animation: hsm-fade-in 0.2s ease-out; } @keyframes hsm-fade-in { from { opacity: 0; transform: scale(0.95); } to { opacity: 1; transform: scale(1); } } [data-bs-theme="dark"] .hsm-dialog { background: #1e293b; border-color: rgba(255,255,255,0.1); color: #f8f9fa; } .hsm-header { display: flex; justify-content: space-between; align-items: center; padding: 1rem 1.5rem; border-bottom: 1px solid var(--bs-border-color, rgba(0,0,0,0.1)); background: rgba(0,0,0,0.02); } [data-bs-theme="dark"] .hsm-header { background: rgba(255,255,255,0.02); border-color: rgba(255,255,255,0.1); } .hsm-close { background: transparent; border: none; color: inherit; opacity: 0.5; padding: 0.25rem 0.5rem; border-radius: 0.25rem; font-size: 1.2rem; line-height: 1; transition: opacity 0.2s; } .hsm-close:hover { opacity: 1; } .hsm-body { padding: 1.5rem; } .hsm-url-group { display: flex !important; align-items: stretch; } .hsm-url-group .form-control { flex: 1; min-width: 0; margin: 0; background: var(--bs-secondary-bg, #f8f9fa); border-color: var(--bs-border-color, #dee2e6); border-top-right-radius: 0; border-bottom-right-radius: 0; height: 42px; } .hsm-url-group .btn { flex: 0 0 auto; margin: 0; margin-left: -1px; border-top-left-radius: 0; border-bottom-left-radius: 0; height: 42px; display: flex; align-items: center; justify-content: center; padding: 0 1.25rem; z-index: 2; } [data-bs-theme="dark"] .hsm-url-group .form-control { background: #0f172a; border-color: #334155; color: #e2e8f0; } .hsm-share-grid { display: flex; flex-direction: column; gap: 0.5rem; } .hsm-share-grid .btn { display: flex; align-items: center; justify-content: center; font-size: 0.9rem; padding: 0.6rem; border-color: var(--bs-border-color); width: 100%; } [data-bs-theme="dark"] .hsm-share-grid .btn { color: #e2e8f0; border-color: #475569; } [data-bs-theme="dark"] .hsm-share-grid .btn:hover { background: #334155; border-color: #cbd5e1; } </style> <script> (function(){ const modal = document.getElementById('headingShareModal'); if(!modal) return; const input = modal.querySelector('#headingShareInput'); const copyBtn = modal.querySelector('.hsm-copy'); const twitter = modal.querySelector('#share-twitter'); const linkedin = modal.querySelector('#share-linkedin'); const facebook = modal.querySelector('#share-facebook'); const closeBtn = modal.querySelector('.hsm-close'); let lastFocus=null; let trapBound=false; function buildUrl(id){ return window.location.origin + window.location.pathname + '#' + id; } function isOpen(){ return !modal.hasAttribute('hidden'); } function hydrate(id){ const url=buildUrl(id); input.value=url; const enc=encodeURIComponent(url); const text=encodeURIComponent(document.title); if(twitter) twitter.href=`https://twitter.com/intent/tweet?url=${enc}&text=${text}`; if(linkedin) linkedin.href=`https://www.linkedin.com/sharing/share-offsite/?url=${enc}`; if(facebook) facebook.href=`https://www.facebook.com/sharer/sharer.php?u=${enc}`; } function openModal(id){ lastFocus=document.activeElement; hydrate(id); if(!isOpen()){ modal.removeAttribute('hidden'); } requestAnimationFrame(()=>{ input.focus(); }); trapFocus(); } function closeModal(){ if(!isOpen()) return; modal.setAttribute('hidden',''); if(lastFocus && typeof lastFocus.focus==='function') lastFocus.focus(); } function copyCurrent(){ try{ navigator.clipboard.writeText(input.value).then(()=>feedback(true),()=>fallback()); } catch(e){ fallback(); } } function fallback(){ input.select(); try{ document.execCommand('copy'); feedback(true);}catch(e){ feedback(false);} } function feedback(ok){ if(!copyBtn) return; const icon=copyBtn.querySelector('i'); if(!icon) return; const prev=copyBtn.getAttribute('data-prev')||icon.className; if(!copyBtn.getAttribute('data-prev')) copyBtn.setAttribute('data-prev',prev); icon.className= ok ? '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>GQL (Graph Query Language) is the ISO/IEC 39075:2024 international standard for querying property graph databases. It provides a declarative syntax for pattern matching, data manipulation, and graph traversal, similar to SQL for relational databases but optimized for highly connected data. Key characteristics: <ul> <li>Declarative: Describe what you want, not how to get it</li> <li>Pattern-based: Match graph patterns using visual ASCII art syntax</li> <li>Composable: Build complex queries from simple building blocks</li> <li>Type-safe: Strong typing with comprehensive type system</li> <li>Standard: ISO-standardized, vendor-neutral specification</li> </ul> <h3 id="query-structure" class="position-relative d-flex align-items-center group"> Query Structure <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="query-structure" aria-haspopup="dialog" aria-label="Share link: Query Structure"> Share link </button> </h3> <h4 id="basic-query-pattern" class="position-relative d-flex align-items-center group"> Basic Query 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="basic-query-pattern" aria-haspopup="dialog" aria-label="Share link: Basic Query Pattern"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">MATCH pattern WHERE conditions RETURN expressions ORDER BY sort_expressions LIMIT row_count </code></pre></div> <h4 id="complete-query-anatomy" class="position-relative d-flex align-items-center group"> Complete Query Anatomy <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="complete-query-anatomy" aria-haspopup="dialog" aria-label="Share link: Complete Query Anatomy"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Graph pattern clause MATCH (n:Label {property: value})-[r:TYPE]->(m) // Optional patterns OPTIONAL MATCH (n)-[:RELATED]->(opt) // Filtering WHERE n.age > 25 AND m.verified = true // WITH clause for piping WITH n, COUNT(m) AS connections WHERE connections > 10 // Return results RETURN n.name, connections, COLLECT(opt.name) AS related_items // Post-processing ORDER BY connections DESC LIMIT 20 OFFSET 0 </code></pre></div> <h3 id="pattern-matching-syntax" class="position-relative d-flex align-items-center group"> Pattern Matching Syntax <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="pattern-matching-syntax" aria-haspopup="dialog" aria-label="Share link: Pattern Matching Syntax"> Share link </button> </h3> <h4 id="node-patterns" class="position-relative d-flex align-items-center group"> Node 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="node-patterns" aria-haspopup="dialog" aria-label="Share link: Node Patterns"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Anonymous node () // Named node variable (n) // Node with label (n:User) // Multiple labels (n:User:Admin) // Node with properties (n:User {name: 'Alice', age: 30}) // Property pattern matching (n:User) WHERE n.age > 25 </code></pre></div> <h4 id="relationship-patterns" class="position-relative d-flex align-items-center group"> Relationship 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="relationship-patterns" aria-haspopup="dialog" aria-label="Share link: Relationship Patterns"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Undirected relationship (a)-[]-(b) // Directed relationship (a)-->(b) (a)<--(b) // Named relationship (a)-[r]->(b) // Relationship with type (a)-[r:KNOWS]->(b) // Multiple relationship types (a)-[r:KNOWS|FOLLOWS]->(b) // Relationship with properties (a)-[r:KNOWS {since: 2020}]->(b) // Variable-length paths (a)-[*]-(b) // Any length (a)-[*1..3]-(b) // 1 to 3 hops (a)-[*..5]-(b) // Up to 5 hops (a)-[*3..]-(b) // 3 or more hops </code></pre></div> <h4 id="path-patterns" class="position-relative d-flex align-items-center group"> Path 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="path-patterns" aria-haspopup="dialog" aria-label="Share link: Path Patterns"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Named path MATCH path = (a)-[:KNOWS*]->(b) RETURN path // Shortest path MATCH path = SHORTEST (a)-[:KNOWS*]-(b) WHERE a.name = 'Alice' AND b.name = 'Bob' RETURN path // All shortest paths MATCH paths = ALL SHORTEST (a)-[:KNOWS*]-(b) RETURN paths </code></pre></div> <h3 id="data-manipulation-language-dml" class="position-relative d-flex align-items-center group"> Data Manipulation Language (DML) <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="data-manipulation-language-dml" aria-haspopup="dialog" aria-label="Share link: Data Manipulation Language (DML)"> Share link </button> </h3> <h4 id="create" class="position-relative d-flex align-items-center group"> CREATE <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="create" aria-haspopup="dialog" aria-label="Share link: CREATE"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Create nodes CREATE (n:Label {property: value}) // Create relationships MATCH (a:User {id: 1}), (b:User {id: 2}) CREATE (a)-[:KNOWS {since: 2024}]->(b) // Create complex patterns CREATE (a:User {name: 'Alice'})-[:POSTED]->(p:Post {title: 'Hello'}), (a)-[:FOLLOWS]->(b:User {name: 'Bob'}) </code></pre></div> <h4 id="set" class="position-relative d-flex align-items-center group"> SET <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="set" aria-haspopup="dialog" aria-label="Share link: SET"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Set properties MATCH (n:User {id: 1}) SET n.name = 'New Name', n.updated_at = NOW() // Set all properties from map MATCH (n:User {id: 1}) SET n = {name: 'Alice', age: 30} // Add properties from map MATCH (n:User {id: 1}) SET n += {city: 'NYC', verified: true} // Add labels MATCH (n:User {id: 1}) SET n:Admin:Verified </code></pre></div> <h4 id="delete" class="position-relative d-flex align-items-center group"> DELETE <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="delete" aria-haspopup="dialog" aria-label="Share link: DELETE"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Delete relationships MATCH (a)-[r:KNOWS]->(b) WHERE a.id = 1 DELETE r // Delete nodes (must not have relationships) MATCH (n:User {id: 1}) DELETE n // Delete node and all relationships MATCH (n:User {id: 1}) DETACH DELETE n // Conditional delete MATCH (n:TempData) WHERE n.created_at < DATE('2024-01-01') DETACH DELETE n </code></pre></div> <h4 id="merge" class="position-relative d-flex align-items-center group"> MERGE <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="merge" aria-haspopup="dialog" aria-label="Share link: MERGE"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Upsert pattern MERGE (u:User {email: 'alice@example.com'}) ON CREATE SET u.created_at = NOW(), u.login_count = 1 ON MATCH SET u.last_login = NOW(), u.login_count = u.login_count + 1 RETURN u // Merge relationships MATCH (a:User {id: 1}), (b:User {id: 2}) MERGE (a)-[r:KNOWS]->(b) ON CREATE SET r.since = NOW() RETURN r </code></pre></div> <h3 id="schema-definition-language-ddl" class="position-relative d-flex align-items-center group"> Schema Definition Language (DDL) <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="schema-definition-language-ddl" aria-haspopup="dialog" aria-label="Share link: Schema Definition Language (DDL)"> Share link </button> </h3> <h4 id="indexes" class="position-relative d-flex align-items-center group"> Indexes <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="indexes" aria-haspopup="dialog" aria-label="Share link: Indexes"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Create index CREATE INDEX FOR (n:Label) ON (n.property) // Named index CREATE INDEX index_name FOR (n:Label) ON (n.property) // Composite index CREATE INDEX FOR (n:Label) ON (n.prop1, n.prop2, n.prop3) // Index types CREATE INDEX FOR (n:Label) ON (n.property) // B-tree (default) CREATE HASH INDEX FOR (n:Label) ON (n.property) // Hash CREATE TEXT INDEX FOR (n:Label) ON (n.property) // Full-text CREATE VECTOR INDEX FOR (n:Label) ON (n.embedding) // Vector similarity // Drop index DROP INDEX index_name </code></pre></div> <h4 id="constraints" class="position-relative d-flex align-items-center group"> Constraints <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" aria-haspopup="dialog" aria-label="Share link: Constraints"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Uniqueness CREATE CONSTRAINT ON (n:Label) ASSERT n.property IS UNIQUE // Existence CREATE CONSTRAINT ON (n:Label) ASSERT EXISTS(n.property) // Type constraint CREATE CONSTRAINT ON (n:Label) ASSERT n.property IS :: TYPE // Check constraint CREATE CONSTRAINT ON (n:Label) ASSERT n.age >= 0 AND n.age <= 150 // Drop constraint DROP CONSTRAINT constraint_name </code></pre></div> <h3 id="expressions-and-operators" class="position-relative d-flex align-items-center group"> Expressions and Operators <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="expressions-and-operators" aria-haspopup="dialog" aria-label="Share link: Expressions and Operators"> Share link </button> </h3> <h4 id="comparison" class="position-relative d-flex align-items-center group"> 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="comparison" aria-haspopup="dialog" aria-label="Share link: Comparison"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">=, <>, !=, <, >, <=, >= IS NULL, IS NOT NULL IN [list] BETWEEN min AND max STARTS WITH, ENDS WITH, CONTAINS =~ (regex match) </code></pre></div> <h4 id="logical" class="position-relative d-flex align-items-center group"> Logical <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="logical" aria-haspopup="dialog" aria-label="Share link: Logical"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">AND, OR, NOT, XOR </code></pre></div> <h4 id="arithmetic" class="position-relative d-flex align-items-center group"> Arithmetic <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="arithmetic" aria-haspopup="dialog" aria-label="Share link: Arithmetic"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">+, -, *, /, %, ^ </code></pre></div> <h4 id="string" class="position-relative d-flex align-items-center group"> String <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="string" aria-haspopup="dialog" aria-label="Share link: String"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">+ (concatenation) || (concatenation) </code></pre></div> <h4 id="list" class="position-relative d-flex align-items-center group"> List <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="list" aria-haspopup="dialog" aria-label="Share link: List"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">[element1, element2, ...] // Literal list[index] // Access list[start..end] // Slice IN list // Membership + (concatenation) </code></pre></div> <h3 id="built-in-functions" class="position-relative d-flex align-items-center group"> Built-in Functions <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="built-in-functions" aria-haspopup="dialog" aria-label="Share link: Built-in Functions"> Share link </button> </h3> <h4 id="aggregation" class="position-relative d-flex align-items-center group"> Aggregation <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="aggregation" aria-haspopup="dialog" aria-label="Share link: Aggregation"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">COUNT(*), COUNT(expr) SUM(expr) AVG(expr) MIN(expr), MAX(expr) COLLECT(expr) STRING_AGG(expr, delimiter) </code></pre></div> <h4 id="string-1" class="position-relative d-flex align-items-center group"> String <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="string-1" aria-haspopup="dialog" aria-label="Share link: String"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">UPPER(str), LOWER(str) TRIM(str), LTRIM(str), RTRIM(str) SUBSTRING(str, start, length) LENGTH(str) CONCAT(str1, str2, ...) REPLACE(str, search, replace) SPLIT(str, delimiter) </code></pre></div> <h4 id="mathematical" class="position-relative d-flex align-items-center group"> Mathematical <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="mathematical" aria-haspopup="dialog" aria-label="Share link: Mathematical"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">ABS(num), CEIL(num), FLOOR(num), ROUND(num, precision) SQRT(num), POWER(base, exponent) SIN(num), COS(num), TAN(num) LOG(num), LOG10(num), EXP(num) RAND() </code></pre></div> <h4 id="temporal" class="position-relative d-flex align-items-center group"> Temporal <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="temporal" aria-haspopup="dialog" aria-label="Share link: Temporal"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">NOW(), CURRENT_TIMESTAMP, CURRENT_DATE, CURRENT_TIME DATE(str), DATETIME(str), TIME(str) DURATION(str) </code></pre></div> <h4 id="list-1" class="position-relative d-flex align-items-center group"> List <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="list-1" aria-haspopup="dialog" aria-label="Share link: List"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">SIZE(list) HEAD(list), LAST(list), TAIL(list) REVERSE(list) RANGE(start, end, step) </code></pre></div> <h4 id="path" class="position-relative d-flex align-items-center group"> Path <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="path" aria-haspopup="dialog" aria-label="Share link: Path"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">LENGTH(path) NODES(path) RELATIONSHIPS(path) </code></pre></div> <h4 id="type-conversion" class="position-relative d-flex align-items-center group"> Type Conversion <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="type-conversion" aria-haspopup="dialog" aria-label="Share link: Type Conversion"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">TOSTRING(val) TOINTEGER(val) TOFLOAT(val) TOBOOLEAN(val) </code></pre></div> <h3 id="advanced-features" class="position-relative d-flex align-items-center group"> Advanced Features <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="advanced-features" aria-haspopup="dialog" aria-label="Share link: Advanced Features"> Share link </button> </h3> <h4 id="subqueries" class="position-relative d-flex align-items-center group"> Subqueries <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="subqueries" aria-haspopup="dialog" aria-label="Share link: Subqueries"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// EXISTS subquery MATCH (u:User) WHERE EXISTS { MATCH (u)-[:PURCHASED]->(p:Product) WHERE p.price > 1000 } RETURN u // COUNT subquery MATCH (u:User) RETURN u.name, COUNT { MATCH (u)-[:POSTED]->(p:Post) WHERE p.published = true } AS post_count </code></pre></div> <h4 id="case-expressions" class="position-relative d-flex align-items-center group"> CASE Expressions <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="case-expressions" aria-haspopup="dialog" aria-label="Share link: CASE Expressions"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">MATCH (u:User) RETURN u.name, CASE WHEN u.age < 18 THEN 'minor' WHEN u.age < 65 THEN 'adult' ELSE 'senior' END AS age_group </code></pre></div> <h4 id="list-comprehensions" class="position-relative d-flex align-items-center group"> List Comprehensions <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="list-comprehensions" aria-haspopup="dialog" aria-label="Share link: List Comprehensions"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">MATCH (u:User) RETURN [tag IN u.tags WHERE LENGTH(tag) > 5] AS long_tags RETURN [x IN RANGE(1, 10) | x * x] AS squares </code></pre></div> <h4 id="pattern-comprehensions" class="position-relative d-flex align-items-center group"> Pattern Comprehensions <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="pattern-comprehensions" aria-haspopup="dialog" aria-label="Share link: Pattern Comprehensions"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">MATCH (u:User) RETURN u.name, [(u)-[:FRIEND]->(f) | f.name] AS friend_names </code></pre></div> <h3 id="transaction-control" class="position-relative d-flex align-items-center group"> Transaction Control <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-control" aria-haspopup="dialog" aria-label="Share link: Transaction Control"> Share link </button> </h3><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN TRANSACTION; // statements COMMIT; // Or rollback ROLLBACK; // Savepoints BEGIN TRANSACTION; SAVEPOINT sp1; // statements ROLLBACK TO SAVEPOINT sp1; COMMIT; </code></pre></div> <h3 id="query-optimization" class="position-relative d-flex align-items-center group"> Query Optimization <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="query-optimization" aria-haspopup="dialog" aria-label="Share link: Query Optimization"> Share link </button> </h3> <h4 id="explain-and-profile" class="position-relative d-flex align-items-center group"> EXPLAIN and PROFILE <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="explain-and-profile" aria-haspopup="dialog" aria-label="Share link: EXPLAIN and PROFILE"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Show query plan EXPLAIN MATCH (u:User)-[:KNOWS]->(f) RETURN u, f // Show execution metrics PROFILE MATCH (u:User)-[:KNOWS]->(f) RETURN u, f </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><ol> <li>Use Parameters: Never concatenate user input into queries</li> <li>Create Indexes: Index frequently queried properties</li> <li>Limit Results: Always use LIMIT for exploratory queries</li> <li>Filter Early: Apply WHERE clauses before expensive operations</li> <li>Use WITH: Break complex queries into readable stages</li> <li>Avoid Cartesian Products: Always connect patterns with relationships</li> <li>Profile Queries: Use PROFILE to identify bottlenecks</li> </ol> <h3 id="related-topics" class="position-relative d-flex align-items-center group"> Related Topics <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-topics" aria-haspopup="dialog" aria-label="Share link: Related Topics"> Share link </button> </h3><ul> <li>GQL Syntax: Detailed syntax guide</li> <li>GQL Operators: Complete operator reference</li> <li>GQL Functions: Built-in function documentation</li> <li>Data Types: GQL type system</li> <li>ISO Standard: ISO/IEC 39075:2024 specification</li> </ul> <h3 id="further-reading" class="position-relative d-flex align-items-center group"> Further Reading <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="further-reading" aria-haspopup="dialog" aria-label="Share link: Further Reading"> Share link </button> </h3><ul> <li><a href="/tags/gql-syntax/" >GQL Syntax Guide</a> - Detailed syntax documentation</li> <li><a href="/tags/operators/" >GQL Operators</a> - Operator reference</li> <li><a href="/tags/functions/" >Built-in Functions</a> - Function catalog</li> <li><a href="/tags/types/" >Data Types</a> - Type system documentation</li> <li><a href="/tags/iso-standard/" >ISO/IEC 39075:2024</a> - Official standard</li> </ul> <h3 id="advanced-pattern-techniques" class="position-relative d-flex align-items-center group"> Advanced Pattern Techniques <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="advanced-pattern-techniques" aria-haspopup="dialog" aria-label="Share link: Advanced Pattern Techniques"> Share link </button> </h3> <h4 id="conditional-pattern-matching" class="position-relative d-flex align-items-center group"> Conditional Pattern Matching <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-pattern-matching" aria-haspopup="dialog" aria-label="Share link: Conditional Pattern Matching"> Share link </button> </h4>Use conditional logic within patterns for complex queries: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Pattern with conditional relationship types MATCH (user:User)-[r:FOLLOWS|SUBSCRIBES]->(target) WHERE type(r) = 'FOLLOWS' AND r.since < date('2024-01-01') OR type(r) = 'SUBSCRIBES' AND r.tier = 'premium' RETURN user.name, target.name, type(r) AS relationship_type; // Multiple optional patterns with fallbacks MATCH (product:Product) OPTIONAL MATCH (product)<-[:REVIEWED]-(review) WHERE review.rating >= 4 OPTIONAL MATCH (product)<-[:PURCHASED]-(buyer:User) WHERE buyer.verified = true RETURN product.name, COALESCE(avg(review.rating), 0) AS avg_rating, count(DISTINCT buyer) AS verified_purchases; </code></pre></div> <h4 id="dynamic-pattern-construction" class="position-relative d-flex align-items-center group"> Dynamic Pattern Construction <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="dynamic-pattern-construction" aria-haspopup="dialog" aria-label="Share link: Dynamic Pattern Construction"> Share link </button> </h4>Build patterns dynamically based on input: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Variable relationship depth based on parameter MATCH path = (start:Node {id: $start_id}) -[:CONNECTED*1..$max_hops]->(end:Node) WHERE end.category IN $categories RETURN path, length(path) AS hops ORDER BY hops LIMIT $result_limit; // Label matching with pattern variables MATCH (n) WHERE any(label IN labels(n) WHERE label IN $allowed_labels) AND n.status = 'active' RETURN n; </code></pre></div> <h4 id="recursive-patterns-and-ctes" class="position-relative d-flex align-items-center group"> Recursive Patterns and CTEs <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="recursive-patterns-and-ctes" aria-haspopup="dialog" aria-label="Share link: Recursive Patterns and CTEs"> Share link </button> </h4>Common Table Expressions for complex hierarchies: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// WITH for pipeline processing WITH ['root', 'admin', 'moderator'] AS privileged_roles MATCH (u:User) WHERE u.role IN privileged_roles WITH u, SIZE((u)-[:MANAGES]->(:User)) AS direct_reports WHERE direct_reports > 0 RETURN u.name, u.role, direct_reports ORDER BY direct_reports DESC; // Multiple WITH clauses for incremental filtering MATCH (product:Product) WITH product, SIZE((product)<-[:PURCHASED]-()) AS purchase_count WHERE purchase_count > 100 WITH product, purchase_count, avg([(product)<-[r:REVIEWED]-() | r.rating]) AS avg_rating WHERE avg_rating > 4.0 RETURN product.name, purchase_count, avg_rating ORDER BY purchase_count * avg_rating DESC LIMIT 20; </code></pre></div> <h3 id="performance-optimization-strategies" class="position-relative d-flex align-items-center group"> Performance Optimization 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="performance-optimization-strategies" aria-haspopup="dialog" aria-label="Share link: Performance Optimization Strategies"> Share link </button> </h3> <h4 id="index-selection-and-hints" class="position-relative d-flex align-items-center group"> Index Selection and Hints <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="index-selection-and-hints" aria-haspopup="dialog" aria-label="Share link: Index Selection and Hints"> Share link </button> </h4>Guide the query planner with index hints: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Force specific index usage MATCH (u:User {email: $email}) USING INDEX user_email_idx RETURN u; // Composite index hint MATCH (p:Product) WHERE p.category = $category AND p.price BETWEEN $min_price AND $max_price USING INDEX product_category_price_idx RETURN p.name, p.price ORDER BY p.price; // Scan hint for small result sets MATCH (n:SmallTable) USING SCAN WHERE n.rare_property = $value RETURN n; </code></pre></div> <h4 id="query-plan-analysis" class="position-relative d-flex align-items-center group"> Query Plan Analysis <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="query-plan-analysis" aria-haspopup="dialog" aria-label="Share link: Query Plan Analysis"> Share link </button> </h4>Understand and optimize execution plans: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Detailed execution plan EXPLAIN MATCH (u:User)-[:PURCHASED]->(p:Product)<-[:PURCHASED]-(similar:User) WHERE u.id = $user_id AND NOT (u)-[:PURCHASED]->(recommended:Product)<-[:PURCHASED]-(similar) RETURN recommended.name, count(similar) AS similarity_score ORDER BY similarity_score DESC LIMIT 10; // Runtime statistics PROFILE MATCH (u:User)-[:PURCHASED]->(p:Product)<-[:PURCHASED]-(similar:User) WHERE u.id = $user_id RETURN count(similar) AS connections; // Expected plan output: // Projection (estimated rows: 1000) // Aggregation (estimated rows: 1000) // Expand (estimated rows: 50000) // Expand (estimated rows: 1000) // IndexSeek (estimated rows: 1) </code></pre></div> <h4 id="parallel-query-execution" class="position-relative d-flex align-items-center group"> Parallel Query Execution <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="parallel-query-execution" aria-haspopup="dialog" aria-label="Share link: Parallel Query Execution"> Share link </button> </h4>Leverage parallel processing: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Parallel batch processing CALL { MATCH (u:User) WHERE u.status = 'pending' WITH u LIMIT 10000 SET u.status = 'processing' RETURN count(u) AS processed } IN TRANSACTIONS OF 1000 ROWS; // Parallel aggregation MATCH (event:Event) WHERE event.timestamp >= $start_date WITH event.type AS event_type, count(*) AS count RETURN event_type, count ORDER BY count DESC; </code></pre></div> <h3 id="advanced-data-type-operations" class="position-relative d-flex align-items-center group"> Advanced Data Type 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="advanced-data-type-operations" aria-haspopup="dialog" aria-label="Share link: Advanced Data Type Operations"> Share link </button> </h3> <h4 id="working-with-lists" class="position-relative d-flex align-items-center group"> Working with Lists <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="working-with-lists" aria-haspopup="dialog" aria-label="Share link: Working with Lists"> Share link </button> </h4>Advanced list manipulation: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// List comprehension with filtering and mapping MATCH (user:User) RETURN user.name, [tag IN user.tags WHERE size(tag) > 3 | upper(tag)] AS formatted_tags, [x IN range(1, 10) WHERE x % 2 = 0 | x * x] AS even_squares; // List reduction MATCH path = (start)-[:CONNECTED*]-(end) WHERE start.id = $start_id AND end.id = $end_id WITH path, reduce(total = 0, rel IN relationships(path) | total + rel.weight) AS path_weight RETURN path, path_weight ORDER BY path_weight LIMIT 1; // List slicing and indexing MATCH (article:Article) RETURN article.title, article.tags[0..3] AS top_tags, article.tags[-1] AS last_tag, size(article.tags) AS tag_count; </code></pre></div> <h4 id="map-operations" class="position-relative d-flex align-items-center group"> Map 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="map-operations" aria-haspopup="dialog" aria-label="Share link: Map Operations"> Share link </button> </h4>Working with map data types: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Map construction MATCH (user:User) RETURN { id: user.id, name: user.name, profile: { email: user.email, verified: user.verified, created: user.created_at }, stats: { login_count: user.login_count, last_login: user.last_login } } AS user_object; // Map merging MATCH (product:Product) SET product += { updated_at: datetime(), updated_by: $user_id }; // Accessing nested map properties MATCH (config:Config) WHERE config.settings.notifications.email = true RETURN config.settings; </code></pre></div> <h4 id="temporal-operations" class="position-relative d-flex align-items-center group"> Temporal 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="temporal-operations" aria-haspopup="dialog" aria-label="Share link: Temporal Operations"> Share link </button> </h4>Advanced date and time manipulation: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Date arithmetic and formatting MATCH (subscription:Subscription) WITH subscription, duration.between(subscription.start_date, date()) AS active_duration WHERE active_duration > duration('P1Y') // Active for more than 1 year RETURN subscription.user_id, date.format(subscription.start_date, 'YYYY-MM-DD') AS start, duration.inDays(active_duration) AS days_active; // Time zone conversions MATCH (event:Event) RETURN event.title, datetime.convert(event.timestamp, 'UTC', 'America/New_York') AS local_time; // Temporal ranges MATCH (session:Session) WHERE session.start_time >= datetime('2025-01-01T00:00:00Z') AND session.end_time < datetime('2025-02-01T00:00:00Z') WITH session, duration.between(session.start_time, session.end_time) AS duration RETURN date.truncate(session.start_time, 'day') AS day, avg(duration.inMinutes(duration)) AS avg_session_minutes ORDER BY day; </code></pre></div> <h3 id="error-handling-and-validation" class="position-relative d-flex align-items-center group"> Error Handling and Validation <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-and-validation" aria-haspopup="dialog" aria-label="Share link: Error Handling and Validation"> Share link </button> </h3> <h4 id="input-validation" class="position-relative d-flex align-items-center group"> Input Validation <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="input-validation" aria-haspopup="dialog" aria-label="Share link: Input Validation"> Share link </button> </h4>Validate query inputs: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Parameter validation MATCH (user:User) WHERE user.id = $user_id WITH user WHERE user IS NOT NULL // Ensure user exists AND user.status = 'active' AND user.email =~ '^[\\w.-]+@[\\w.-]+\\.\\w+$' // Email format RETURN user; // Type checking MATCH (node) WHERE id(node) = $node_id WITH node WHERE node:User OR node:Admin // Ensure correct type RETURN node; // Constraint validation before update MATCH (account:Account {id: $account_id}) WHERE account.balance >= $withdrawal_amount SET account.balance = account.balance - $withdrawal_amount RETURN account.balance; </code></pre></div> <h4 id="error-recovery-patterns" class="position-relative d-flex align-items-center group"> Error Recovery 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="error-recovery-patterns" aria-haspopup="dialog" aria-label="Share link: Error Recovery Patterns"> Share link </button> </h4>Handle errors gracefully: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// OPTIONAL MATCH for nullable relationships MATCH (user:User {id: $user_id}) OPTIONAL MATCH (user)-[:HAS_PROFILE]->(profile:Profile) RETURN user.name, COALESCE(profile.bio, 'No profile') AS bio; // CASE for conditional logic MATCH (product:Product) RETURN product.name, CASE WHEN product.stock > 100 THEN 'In Stock' WHEN product.stock > 0 THEN 'Low Stock' ELSE 'Out of Stock' END AS availability; // TRY-CATCH pattern with EXISTS MATCH (order:Order {id: $order_id}) WITH order, CASE WHEN EXISTS { MATCH (order)-[:CONTAINS]->(item:Item) WHERE item.available = false } THEN 'unavailable_items' ELSE 'ready' END AS order_status RETURN order, order_status; </code></pre></div> <h3 id="stored-procedures-and-user-defined-functions" class="position-relative d-flex align-items-center group"> Stored Procedures and User-Defined Functions <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="stored-procedures-and-user-defined-functions" aria-haspopup="dialog" aria-label="Share link: Stored Procedures and User-Defined Functions"> Share link </button> </h3> <h4 id="calling-built-in-procedures" class="position-relative d-flex align-items-center group"> Calling Built-in Procedures <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="calling-built-in-procedures" aria-haspopup="dialog" aria-label="Share link: Calling Built-in Procedures"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Database statistics CALL dbms.info() YIELD name, value RETURN name, value; // Index management CALL dbms.indexes.list() YIELD name, type, state WHERE state = 'online' RETURN name, type; // Transaction monitoring CALL dbms.transactions.list() YIELD transactionId, elapsedTime WHERE elapsedTime > duration('PT30S') RETURN transactionId, elapsedTime ORDER BY elapsedTime DESC; </code></pre></div> <h4 id="custom-aggregation-functions" class="position-relative d-flex align-items-center group"> Custom Aggregation Functions <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="custom-aggregation-functions" aria-haspopup="dialog" aria-label="Share link: Custom Aggregation Functions"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">// Custom aggregation with COLLECT and list operations MATCH (user:User)-[:PURCHASED]->(product:Product) WITH user, COLLECT(product.price) AS prices RETURN user.name, reduce(sum = 0.0, price IN prices | sum + price) AS total_spent, reduce(count = 0, price IN prices | count + 1) AS purchase_count, reduce(sum = 0.0, price IN prices | sum + price) / reduce(count = 0, price IN prices | count + 1) AS avg_price; </code></pre></div> <h3 id="integration-with-external-systems" class="position-relative d-flex align-items-center group"> Integration with External Systems <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="integration-with-external-systems" aria-haspopup="dialog" aria-label="Share link: Integration with External Systems"> Share link </button> </h3> <h4 id="parameterized-queries-for-apis" class="position-relative d-flex align-items-center group"> Parameterized Queries for APIs <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="parameterized-queries-for-apis" aria-haspopup="dialog" aria-label="Share link: Parameterized Queries for APIs"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-python" data-lang="python"># REST API integration from fastapi import FastAPI, HTTPException from geode_client import Client app = FastAPI() @app.get("/api/users/{user_id}/recommendations") async def get_recommendations(user_id: int, limit: int = 10): client = Client(host="localhost", port=3141) async with client.connection() as conn: query = """ MATCH (u:User {id: $user_id})-[:PURCHASED]->(p:Product) <-[:PURCHASED]-(similar:User)-[:PURCHASED]->(rec:Product) WHERE NOT (u)-[:PURCHASED]->(rec) WITH rec, count(DISTINCT similar) AS score WHERE score >= 3 RETURN rec.id, rec.name, rec.price, score ORDER BY score DESC LIMIT $limit """ result, _ = await conn.query(query, { 'user_id': user_id, 'limit': limit }) return { 'user_id': user_id, 'recommendations': [ { 'id': row['rec.id'], 'name': row['rec.name'], 'price': row['rec.price'], 'score': row['score'] } for row in result.rows ] } </code></pre></div> <h4 id="graphql-integration" class="position-relative d-flex align-items-center group"> GraphQL Integration <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="graphql-integration" aria-haspopup="dialog" aria-label="Share link: GraphQL Integration"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-python" data-lang="python"># GraphQL resolver with GQL backend import strawberry from typing import List @strawberry.type class User: id: int name: str email: str friends: List['User'] @strawberry.type class Query: @strawberry.field async def user(self, id: int) -> User: client = Client(host="localhost", port=3141) async with client.connection() as conn: result, _ = await conn.query(""" MATCH (u:User {id: $id}) OPTIONAL MATCH (u)-[:FRIEND]->(f:User) RETURN u.id AS id, u.name AS name, u.email AS email, COLLECT({ id: f.id, name: f.name, email: f.email }) AS friends """, {'id': id}) row = result.rows[0] if result.rows else None if not row: raise ValueError(f"User {id} not found") return User( id=row['id'], name=row['name'], email=row['email'], friends=[ User(id=f['id'], name=f['name'], email=f['email'], friends=[]) for f in row['friends'] if f['id'] is not None ] ) </code></pre></div> <h3 id="troubleshooting-guide" class="position-relative d-flex align-items-center group"> Troubleshooting Guide <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="troubleshooting-guide" aria-haspopup="dialog" aria-label="Share link: Troubleshooting Guide"> Share link </button> </h3> <h4 id="common-query-errors" class="position-relative d-flex align-items-center group"> Common Query 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="common-query-errors" aria-haspopup="dialog" aria-label="Share link: Common Query Errors"> Share link </button> </h4>Error: Syntax error near line X <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- WRONG: Missing closing parenthesis MATCH (u:User {id: 123} RETURN u; -- CORRECT: MATCH (u:User {id: 123}) RETURN u; </code></pre></div>Error: Type mismatch <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- WRONG: Comparing string to integer MATCH (u:User) WHERE u.age = '30' -- age is INTEGER RETURN u; -- CORRECT: MATCH (u:User) WHERE u.age = 30 RETURN u; </code></pre></div>Error: Undefined variable <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- WRONG: Using variable not in scope MATCH (u:User) WHERE friend.age > 25 -- friend not defined RETURN u; -- CORRECT: MATCH (u:User)-[:FRIEND]->(friend:User) WHERE friend.age > 25 RETURN u; </code></pre></div> <h4 id="performance-troubleshooting" class="position-relative d-flex align-items-center group"> Performance Troubleshooting <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-troubleshooting" aria-haspopup="dialog" aria-label="Share link: Performance Troubleshooting"> Share link </button> </h4>Slow query diagnosis: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Step 1: Check execution plan EXPLAIN [your query]; -- Step 2: Profile with metrics PROFILE [your query]; -- Step 3: Check index usage CALL dbms.indexes.list() YIELD name, properties, state RETURN name, properties, state; -- Step 4: Add missing indexes CREATE INDEX user_age_idx FOR (u:User) ON (u.age); </code></pre></div>Large result set issues: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Add LIMIT to queries MATCH (n:Node) RETURN n LIMIT 1000; -- Prevent unbounded results -- Use aggregation instead of collecting all rows MATCH (u:User)-[:PURCHASED]->(p:Product) RETURN p.category, count(u) AS buyers INSTEAD OF RETURN p, COLLECT(u); </code></pre></div>This reference provides comprehensive documentation for writing GQL queries in Geode, from basic pattern matching to advanced features and optimization techniques.

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