Computed Properties - Dynamic Calculated Fields in Geode | Tags

<h2 id="computed-properties" class="position-relative d-flex align-items-center group"> Computed Properties <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="computed-properties" aria-haspopup="dialog" aria-label="Share link: Computed Properties"> 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; letter-spacing: 0.5px;">Share via</div> <div class="hsm-share-grid"> <a id="share-twitter" class="btn btn-outline-secondary w-100" target="_blank" rel="noopener noreferrer"> Twitter </a> <a id="share-linkedin" class="btn btn-outline-secondary w-100" target="_blank" rel="noopener noreferrer"> LinkedIn </a> <a id="share-facebook" class="btn btn-outline-secondary w-100" target="_blank" rel="noopener noreferrer"> Facebook </a> </div> </div> </div> </div> <style> .heading-share-modal { position: fixed; inset: 0; display: flex; justify-content: center; align-items: center; background: rgba(0, 0, 0, 0.6); z-index: 1050; padding: 1rem; backdrop-filter: blur(4px); -webkit-backdrop-filter: blur(4px); } .heading-share-modal[hidden] { display: none !important; } .hsm-dialog { max-width: 420px; width: 100%; background: var(--bs-body-bg, #fff); color: var(--bs-body-color, #212529); border: 1px solid var(--bs-border-color, rgba(0,0,0,0.1)); border-radius: 1rem; box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25); 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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>Computed properties are node or edge properties whose values are automatically calculated from other data through formulas and expressions. Unlike stored properties that persist static values, computed properties derive their values dynamically from base properties, relationships, or aggregations, ensuring they always reflect the current state of your graph. Computed properties are type-safe, indexable, and eliminate data redundancy while maintaining query performance. <h3 id="computed-property-fundamentals" class="position-relative d-flex align-items-center group"> Computed Property 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="computed-property-fundamentals" aria-haspopup="dialog" aria-label="Share link: Computed Property Fundamentals"> Share link </button> </h3> <h4 id="what-are-computed-properties" class="position-relative d-flex align-items-center group"> What are Computed Properties? <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-are-computed-properties" aria-haspopup="dialog" aria-label="Share link: What are Computed Properties?"> Share link </button> </h4>Computed properties are dynamically calculated: Formula-Based - Derived from expressions Always Current - Automatically recalculated Type-Safe - Strongly typed results Indexed - Can be indexed for queries <h4 id="use-cases" class="position-relative d-flex align-items-center group"> Use Cases <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-cases" aria-haspopup="dialog" aria-label="Share link: Use Cases"> Share link </button> </h4><ul> <li>Derived Values - Full name from first/last</li> <li>Calculations - Age from birthdate</li> <li>Aggregations - Total from line items</li> <li>Transformations - Uppercase email</li> </ul> <h3 id="defining-computed-properties" class="position-relative d-flex align-items-center group"> Defining Computed Properties <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="defining-computed-properties" aria-haspopup="dialog" aria-label="Share link: Defining Computed Properties"> Share link </button> </h3> <h4 id="simple-computations" class="position-relative d-flex align-items-center group"> Simple Computations <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="simple-computations" aria-haspopup="dialog" aria-label="Share link: Simple Computations"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Property type with computed fields CREATE PROPERTY TYPE Person ( first_name STRING, last_name STRING, birthdate DATE, -- Computed properties full_name STRING COMPUTED AS (first_name || ' ' || last_name), age INTEGER COMPUTED AS (YEAR(CURRENT_DATE) - YEAR(birthdate)), initials STRING COMPUTED AS ( SUBSTRING(first_name, 1, 1) || SUBSTRING(last_name, 1, 1) ) ); </code></pre></div> <h4 id="aggregations" class="position-relative d-flex align-items-center group"> Aggregations <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="aggregations" aria-haspopup="dialog" aria-label="Share link: Aggregations"> Share link </button> </h4>Compute from relationships: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE User ( id STRING, name STRING, -- Count relationships friend_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:FRIEND]->(:Person) ), -- Sum values total_spent DECIMAL COMPUTED AS ( SELECT SUM(amount) FROM MATCH (this)-[:PLACED]->(o:Order) ) ); </code></pre></div> <h4 id="conditional-logic" class="position-relative d-flex align-items-center group"> Conditional 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="conditional-logic" aria-haspopup="dialog" aria-label="Share link: Conditional Logic"> Share link </button> </h4>Use CASE expressions: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE Account ( balance DECIMAL, credit_score INTEGER, -- Account status status STRING COMPUTED AS ( CASE WHEN balance < 0 THEN 'overdrawn' WHEN balance < 100 THEN 'low_balance' WHEN balance < 10000 THEN 'standard' ELSE 'premium' END ), -- Credit tier credit_tier STRING COMPUTED AS ( CASE WHEN credit_score >= 800 THEN 'excellent' WHEN credit_score >= 700 THEN 'good' WHEN credit_score >= 600 THEN 'fair' ELSE 'poor' END ) ); </code></pre></div> <h3 id="querying-computed-properties" class="position-relative d-flex align-items-center group"> Querying Computed Properties <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="querying-computed-properties" aria-haspopup="dialog" aria-label="Share link: Querying Computed Properties"> Share link </button> </h3> <h4 id="filtering" class="position-relative d-flex align-items-center group"> Filtering <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="filtering" aria-haspopup="dialog" aria-label="Share link: Filtering"> Share link </button> </h4>Use in WHERE clauses: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Find users by computed property MATCH (u:User) WHERE u.age >= 18 AND u.friend_count > 50 RETURN u.name, u.age, u.friend_count; -- Filter by account status MATCH (a:Account) WHERE a.status = 'premium' RETURN a.balance, a.credit_tier; </code></pre></div> <h4 id="sorting" class="position-relative d-flex align-items-center group"> Sorting <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="sorting" aria-haspopup="dialog" aria-label="Share link: Sorting"> Share link </button> </h4>Order by computed values: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Sort by computed property MATCH (u:User) RETURN u.name, u.total_spent ORDER BY u.total_spent DESC LIMIT 10; </code></pre></div> <h4 id="indexing" class="position-relative d-flex align-items-center group"> Indexing <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="indexing" aria-haspopup="dialog" aria-label="Share link: Indexing"> Share link </button> </h4>Create indexes on computed properties: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Index computed property for fast lookup CREATE INDEX idx_user_age ON Person(age); CREATE INDEX idx_account_status ON Account(status); </code></pre></div> <h3 id="performance-considerations" class="position-relative d-flex align-items-center group"> Performance Considerations <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-considerations" aria-haspopup="dialog" aria-label="Share link: Performance Considerations"> Share link </button> </h3> <h4 id="computation-cost" class="position-relative d-flex align-items-center group"> Computation Cost <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="computation-cost" aria-haspopup="dialog" aria-label="Share link: Computation Cost"> Share link </button> </h4>Be mindful of expensive computations: <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Expensive (recalculated every access) total_friends INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:FRIEND*1..3]->(:Person) ); -- Better (simpler calculation) direct_friends INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:FRIEND]->(:Person) ); </code></pre></div> <h3 id="real-world-applications" class="position-relative d-flex align-items-center group"> Real-World Applications <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="real-world-applications" aria-haspopup="dialog" aria-label="Share link: Real-World Applications"> Share link </button> </h3> <h4 id="e-commerce-applications" class="position-relative d-flex align-items-center group"> E-Commerce Applications <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="e-commerce-applications" aria-haspopup="dialog" aria-label="Share link: E-Commerce Applications"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE Product ( base_price DECIMAL, cost DECIMAL, tax_rate DECIMAL, discount_percentage DECIMAL, -- Computed pricing discount_amount DECIMAL COMPUTED AS (base_price * discount_percentage / 100), price_after_discount DECIMAL COMPUTED AS (base_price - discount_amount), tax_amount DECIMAL COMPUTED AS (price_after_discount * tax_rate), final_price DECIMAL COMPUTED AS (price_after_discount + tax_amount), -- Computed metrics profit_margin DECIMAL COMPUTED AS ((price_after_discount - cost) / price_after_discount * 100), is_profitable BOOLEAN COMPUTED AS (profit_margin > 0) ); CREATE PROPERTY TYPE Order ( created_at TIMESTAMP, subtotal DECIMAL, shipping_fee DECIMAL, -- Order age days_since_order INTEGER COMPUTED AS ( DATEDIFF(DAY, created_at, NOW()) ), -- Order status is_recent BOOLEAN COMPUTED AS (days_since_order <= 7), is_stale BOOLEAN COMPUTED AS (days_since_order > 90), -- Order totals total DECIMAL COMPUTED AS (subtotal + shipping_fee), -- Item count from relationships item_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:CONTAINS]->(item:OrderItem) ) ); </code></pre></div> <h4 id="social-network-applications" class="position-relative d-flex align-items-center group"> Social Network Applications <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="social-network-applications" aria-haspopup="dialog" aria-label="Share link: Social Network Applications"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE User ( first_name STRING, last_name STRING, birthdate DATE, join_date TIMESTAMP, -- Profile display full_name STRING COMPUTED AS (first_name || ' ' || last_name), display_name STRING COMPUTED AS ( COALESCE(NULLIF(full_name, ''), 'Anonymous User') ), -- Age calculation age INTEGER COMPUTED AS ( DATEDIFF(YEAR, birthdate, CURRENT_DATE) ), is_adult BOOLEAN COMPUTED AS (age >= 18), age_group STRING COMPUTED AS ( CASE WHEN age < 18 THEN 'minor' WHEN age < 25 THEN 'young_adult' WHEN age < 40 THEN 'adult' WHEN age < 60 THEN 'middle_aged' ELSE 'senior' END ), -- Account tenure membership_days INTEGER COMPUTED AS ( DATEDIFF(DAY, join_date, NOW()) ), membership_years DECIMAL COMPUTED AS (membership_days / 365.25), -- Social metrics from relationships follower_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)<-[:FOLLOWS]-(follower:User) ), following_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:FOLLOWS]->(following:User) ), friend_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:FRIEND]-(friend:User) ), -- Engagement metrics post_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:POSTED]->(post:Post) ), engagement_score DECIMAL COMPUTED AS ( (follower_count * 2.0 + post_count + friend_count) / NULLIF(membership_days, 0) ), -- User tier user_tier STRING COMPUTED AS ( CASE WHEN follower_count >= 10000 THEN 'influencer' WHEN follower_count >= 1000 THEN 'power_user' WHEN follower_count >= 100 THEN 'active' ELSE 'casual' END ) ); </code></pre></div> <h4 id="financial-applications" class="position-relative d-flex align-items-center group"> Financial Applications <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="financial-applications" aria-haspopup="dialog" aria-label="Share link: Financial Applications"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE Account ( balance DECIMAL, credit_limit DECIMAL, interest_rate DECIMAL, monthly_fee DECIMAL, minimum_balance DECIMAL, opened_date DATE, -- Available funds available_credit DECIMAL COMPUTED AS (credit_limit - balance), credit_utilization DECIMAL COMPUTED AS ( balance / NULLIF(credit_limit, 0) * 100 ), -- Account status is_overdrawn BOOLEAN COMPUTED AS (balance < 0), is_below_minimum BOOLEAN COMPUTED AS (balance < minimum_balance), -- Account health health_score INTEGER COMPUTED AS ( CASE WHEN balance >= credit_limit * 0.8 THEN 100 WHEN balance >= credit_limit * 0.5 THEN 80 WHEN balance >= 0 THEN 60 WHEN balance >= credit_limit * -0.2 THEN 40 ELSE 20 END ), -- Account age account_age_months INTEGER COMPUTED AS ( DATEDIFF(MONTH, opened_date, CURRENT_DATE) ), -- Interest calculations monthly_interest DECIMAL COMPUTED AS (balance * interest_rate / 12 / 100), annual_interest DECIMAL COMPUTED AS (balance * interest_rate / 100), -- Transaction metrics total_transactions INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:HAS_TRANSACTION]->(t:Transaction) ), total_deposits DECIMAL COMPUTED AS ( SELECT COALESCE(SUM(amount), 0) FROM MATCH (this)-[:HAS_TRANSACTION]->(t:Transaction) WHERE t.type = 'deposit' ), total_withdrawals DECIMAL COMPUTED AS ( SELECT COALESCE(SUM(amount), 0) FROM MATCH (this)-[:HAS_TRANSACTION]->(t:Transaction) WHERE t.type = 'withdrawal' ) ); </code></pre></div> <h4 id="healthcare-applications" class="position-relative d-flex align-items-center group"> Healthcare Applications <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="healthcare-applications" aria-haspopup="dialog" aria-label="Share link: Healthcare Applications"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE Patient ( first_name STRING, last_name STRING, date_of_birth DATE, height_cm DECIMAL, weight_kg DECIMAL, blood_pressure_systolic INTEGER, blood_pressure_diastolic INTEGER, -- Patient identification full_name STRING COMPUTED AS (first_name || ' ' || last_name), -- Age and demographics age INTEGER COMPUTED AS ( DATEDIFF(YEAR, date_of_birth, CURRENT_DATE) ), age_category STRING COMPUTED AS ( CASE WHEN age < 2 THEN 'infant' WHEN age < 13 THEN 'child' WHEN age < 20 THEN 'adolescent' WHEN age < 65 THEN 'adult' ELSE 'senior' END ), -- Body Mass Index (BMI) height_m DECIMAL COMPUTED AS (height_cm / 100), bmi DECIMAL COMPUTED AS ( weight_kg / (height_m * height_m) ), bmi_category STRING COMPUTED AS ( CASE WHEN bmi < 18.5 THEN 'underweight' WHEN bmi < 25 THEN 'normal' WHEN bmi < 30 THEN 'overweight' ELSE 'obese' END ), -- Blood pressure category bp_category STRING COMPUTED AS ( CASE WHEN blood_pressure_systolic < 120 AND blood_pressure_diastolic < 80 THEN 'normal' WHEN blood_pressure_systolic < 130 AND blood_pressure_diastolic < 80 THEN 'elevated' WHEN blood_pressure_systolic < 140 OR blood_pressure_diastolic < 90 THEN 'stage_1_hypertension' ELSE 'stage_2_hypertension' END ), -- Health indicators has_risk_factors BOOLEAN COMPUTED AS ( bmi >= 30 OR blood_pressure_systolic >= 130 OR age >= 65 ), -- Visit metrics total_visits INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:HAD_VISIT]->(v:Visit) ), last_visit_days_ago INTEGER COMPUTED AS ( SELECT MIN(DATEDIFF(DAY, v.date, NOW())) FROM MATCH (this)-[:HAD_VISIT]->(v:Visit) ), needs_checkup BOOLEAN COMPUTED AS ( last_visit_days_ago IS NULL OR last_visit_days_ago > 365 ) ); </code></pre></div> <h3 id="advanced-computation-patterns" class="position-relative d-flex align-items-center group"> Advanced Computation 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="advanced-computation-patterns" aria-haspopup="dialog" aria-label="Share link: Advanced Computation Patterns"> Share link </button> </h3> <h4 id="multi-level-aggregations" class="position-relative d-flex align-items-center group"> Multi-Level Aggregations <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-level-aggregations" aria-haspopup="dialog" aria-label="Share link: Multi-Level Aggregations"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE Team ( name STRING, budget DECIMAL, -- Direct metrics member_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:HAS_MEMBER]->(u:User) ), -- Project metrics active_projects INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:OWNS]->(p:Project) WHERE p.status = 'active' ), -- Nested aggregation: total tasks across all projects total_tasks INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:OWNS]->(p:Project)-[:HAS_TASK]->(t:Task) ), -- Average completion rate avg_completion_rate DECIMAL COMPUTED AS ( SELECT AVG( CAST(COUNT(completed_tasks) AS DECIMAL) / NULLIF(COUNT(all_tasks), 0) * 100 ) FROM MATCH (this)-[:OWNS]->(p:Project) OPTIONAL MATCH (p)-[:HAS_TASK]->(all_tasks:Task) OPTIONAL MATCH (p)-[:HAS_TASK]->(completed_tasks:Task) WHERE completed_tasks.status = 'completed' ), -- Budget utilization total_spent DECIMAL COMPUTED AS ( SELECT COALESCE(SUM(p.spent), 0) FROM MATCH (this)-[:OWNS]->(p:Project) ), budget_utilization DECIMAL COMPUTED AS ( total_spent / NULLIF(budget, 0) * 100 ), is_over_budget BOOLEAN COMPUTED AS (budget_utilization > 100) ); </code></pre></div> <h4 id="time-series-computations" class="position-relative d-flex align-items-center group"> Time-Series Computations <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="time-series-computations" aria-haspopup="dialog" aria-label="Share link: Time-Series Computations"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE Sensor ( id STRING, location STRING, -- Latest reading latest_reading DECIMAL COMPUTED AS ( SELECT r.value FROM MATCH (this)-[:RECORDED]->(r:Reading) ORDER BY r.timestamp DESC LIMIT 1 ), -- Time-based aggregations readings_last_hour INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[:RECORDED]->(r:Reading) WHERE r.timestamp > NOW() - INTERVAL '1 hour' ), avg_last_hour DECIMAL COMPUTED AS ( SELECT AVG(r.value) FROM MATCH (this)-[:RECORDED]->(r:Reading) WHERE r.timestamp > NOW() - INTERVAL '1 hour' ), max_last_24h DECIMAL COMPUTED AS ( SELECT MAX(r.value) FROM MATCH (this)-[:RECORDED]->(r:Reading) WHERE r.timestamp > NOW() - INTERVAL '24 hours' ), min_last_24h DECIMAL COMPUTED AS ( SELECT MIN(r.value) FROM MATCH (this)-[:RECORDED]->(r:Reading) WHERE r.timestamp > NOW() - INTERVAL '24 hours' ), -- Trend detection trend STRING COMPUTED AS ( CASE WHEN avg_last_hour > max_last_24h * 0.9 THEN 'rising' WHEN avg_last_hour < min_last_24h * 1.1 THEN 'falling' ELSE 'stable' END ), -- Alert conditions is_anomalous BOOLEAN COMPUTED AS ( latest_reading > avg_last_hour * 2 OR latest_reading < avg_last_hour * 0.5 ) ); </code></pre></div> <h4 id="graph-topology-computations" class="position-relative d-flex align-items-center group"> Graph Topology Computations <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-topology-computations" aria-haspopup="dialog" aria-label="Share link: Graph Topology Computations"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE PROPERTY TYPE Node ( id STRING, name STRING, -- Degree computations out_degree INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[]->(n) ), in_degree INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)<-[]-(n) ), total_degree INTEGER COMPUTED AS (out_degree + in_degree), -- Neighborhood metrics neighbors INTEGER COMPUTED AS ( SELECT COUNT(DISTINCT n) FROM MATCH (this)-[]-(n) ), second_order_neighbors INTEGER COMPUTED AS ( SELECT COUNT(DISTINCT n2) FROM MATCH (this)-[]-(n1)-[]-(n2) WHERE n2 <> this ), -- Centrality indicators is_hub BOOLEAN COMPUTED AS (out_degree > 10), is_authority BOOLEAN COMPUTED AS (in_degree > 10), is_bridge BOOLEAN COMPUTED AS ( total_degree = 2 AND out_degree = 1 AND in_degree = 1 ), -- Clustering metrics triangle_count INTEGER COMPUTED AS ( SELECT COUNT(*) FROM MATCH (this)-[]-(n1)-[]-(n2)-[]-(this) WHERE n1 < n2 -- Avoid counting same triangle multiple times ), clustering_coefficient DECIMAL COMPUTED AS ( CASE WHEN neighbors <= 1 THEN 0 ELSE CAST(triangle_count AS DECIMAL) / (neighbors * (neighbors - 1) / 2) END ) ); </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="indexing-computed-properties" class="position-relative d-flex align-items-center group"> Indexing Computed Properties <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="indexing-computed-properties" aria-haspopup="dialog" aria-label="Share link: Indexing Computed Properties"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Index frequently queried computed properties CREATE INDEX idx_user_age ON User(age); CREATE INDEX idx_user_tier ON User(user_tier); CREATE INDEX idx_account_health ON Account(health_score); CREATE INDEX idx_product_profitable ON Product(is_profitable); -- Composite indexes on computed + stored properties CREATE INDEX idx_user_age_country ON User(age, country); CREATE INDEX idx_order_recent_total ON Order(is_recent, total); </code></pre></div> <h4 id="caching-computed-values" class="position-relative d-flex align-items-center group"> Caching Computed Values <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="caching-computed-values" aria-haspopup="dialog" aria-label="Share link: Caching Computed Values"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- For expensive computations, consider materializing CREATE MATERIALIZED VIEW user_engagement_cache AS SELECT u.id, u.full_name, u.follower_count, u.engagement_score, u.user_tier FROM User u WITH REFRESH SCHEDULE '0 */6 * * *'; -- Refresh every 6 hours </code></pre></div> <h4 id="optimizing-aggregation-queries" class="position-relative d-flex align-items-center group"> Optimizing Aggregation Queries <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="optimizing-aggregation-queries" aria-haspopup="dialog" aria-label="Share link: Optimizing Aggregation Queries"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Avoid deep nested aggregations in computed properties -- Instead, use incremental counters updated via triggers CREATE PROPERTY TYPE Team ( name STRING, member_count_cache INTEGER DEFAULT 0, -- Cached value -- Trigger to update cache AFTER INSERT RELATIONSHIP [:HAS_MEMBER] AS ( UPDATE this SET member_count_cache = member_count_cache + 1 ), AFTER DELETE RELATIONSHIP [:HAS_MEMBER] AS ( UPDATE this SET member_count_cache = member_count_cache - 1 ) ); </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="design-guidelines" class="position-relative d-flex align-items-center group"> Design Guidelines <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="design-guidelines" aria-haspopup="dialog" aria-label="Share link: Design Guidelines"> Share link </button> </h4><ol> <li> Keep Formulas Simple: Complex calculations impact query performance <ul> <li>Prefer simple arithmetic over nested subqueries</li> <li>Limit relationship traversal depth to 1-2 hops</li> <li>Use materialized views for complex aggregations</li> </ul> </li> <li> Document Complex Calculations: Add comments explaining business logic <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Customer lifetime value: total purchases adjusted for returns -- and weighted by recency (last 90 days = 1.5x multiplier) lifetime_value DECIMAL COMPUTED AS (...) </code></pre></div></li> <li> Choose Appropriate Data Types: Match types to computation results <ul> <li>Use DECIMAL for financial calculations</li> <li>Use INTEGER for counts and IDs</li> <li>Use BOOLEAN for flags and conditions</li> </ul> </li> <li> Consider Materialization: Cache expensive computations <ul> <li>If computed property takes >100ms to calculate</li> <li>If queried frequently (>1000 times/day)</li> <li>If result changes infrequently</li> </ul> </li> <li> Use Defensive Programming: Handle NULL and edge cases <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">safe_ratio DECIMAL COMPUTED AS ( CAST(numerator AS DECIMAL) / NULLIF(denominator, 0) ) </code></pre></div></li> </ol> <h4 id="testing-guidelines" class="position-relative d-flex align-items-center group"> Testing Guidelines <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="testing-guidelines" aria-haspopup="dialog" aria-label="Share link: Testing Guidelines"> Share link </button> </h4><ol> <li>Unit Test Formulas: Verify calculations with known inputs</li> <li>Test Edge Cases: NULL values, zero division, negative numbers</li> <li>Performance Test: Benchmark with realistic data volumes</li> <li>Validate Types: Ensure computed types match declarations</li> <li>Test Index Usage: Verify indexes on computed properties work</li> </ol> <h4 id="monitoring-and-maintenance" class="position-relative d-flex align-items-center group"> Monitoring and Maintenance <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="monitoring-and-maintenance" aria-haspopup="dialog" aria-label="Share link: Monitoring and Maintenance"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Query to identify slow computed properties SELECT property_name, avg_computation_time_ms, call_count, total_time_ms FROM system.computed_property_stats WHERE avg_computation_time_ms > 50 ORDER BY total_time_ms DESC LIMIT 20; </code></pre></div> <h3 id="common-pitfalls-to-avoid" class="position-relative d-flex align-items-center group"> Common Pitfalls to Avoid <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-pitfalls-to-avoid" aria-haspopup="dialog" aria-label="Share link: Common Pitfalls to Avoid"> Share link </button> </h3><ol> <li>Circular Dependencies: Don’t reference computed properties that depend on each other</li> <li>Deep Relationship Traversal: Limit MATCH depth in computed properties</li> <li>Missing NULL Handling: Always handle potential NULL values</li> <li>Type Mismatches: Ensure expression types match property types</li> <li>Expensive Aggregations: Avoid COUNT(*) on large relationship sets</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><a href="/tags/virtual-properties/" >Virtual Properties</a> - On-demand non-stored calculations</li> <li><a href="/tags/materialized-views/" >Materialized Views</a> - Cached pre-computed results</li> <li><a href="/tags/indexes/" >Indexes</a> - Indexing strategies for computed properties</li> <li><a href="/tags/types/" >Types</a> - Property type definitions</li> <li><a href="/tags/aggregation/" >Aggregation</a> - Aggregation functions and patterns</li> <li><a href="/tags/performance/" >Performance</a> - Query optimization techniques</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="https://www.iso.org/standard/76120.html" aria-label="ISO/IEC 39075:2024 GQL Standard – opens in new window" target="_blank" rel="noopener noreferrer" >ISO/IEC 39075:2024 GQL Standard ↗ </a> - Official GQL specification</li> <li><a href="https://docs.microsoft.com/en-us/sql/relational-databases/tables/specify-computed-columns-in-a-table" aria-label="Computed Columns in SQL – opens in new window" target="_blank" rel="noopener noreferrer" >Computed Columns in SQL ↗ </a> - SQL Server reference</li> <li><a href="https://www.postgresql.org/docs/current/ddl-generated-columns.html" aria-label="Generated Columns (PostgreSQL) – opens in new window" target="_blank" rel="noopener noreferrer" >Generated Columns (PostgreSQL) ↗ </a> - PostgreSQL documentation</li> <li><a href="https://neo4j.com/docs/cypher-manual/current/functions/scalar/#functions-coalesce" aria-label="Derived Attributes – opens in new window" target="_blank" rel="noopener noreferrer" >Derived Attributes ↗ </a> - Graph database patterns</li> </ul>

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