DELETE Clause in GQL

<h2 id="delete-clause-in-gql" class="position-relative d-flex align-items-center group"> DELETE Clause in 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="delete-clause-in-gql" aria-haspopup="dialog" aria-label="Share link: DELETE Clause in GQL"> Share link </button> </h2><div id="headingShareModal" class="heading-share-modal" role="dialog" aria-modal="true" aria-labelledby="headingShareTitle" hidden> <div class="hsm-dialog" role="document"> <div class="hsm-header"> <h2 id="headingShareTitle" class="h6 mb-0 fw-bold">Share this section</h2> <button type="button" class="hsm-close" aria-label="Close"> </button> </div> <div class="hsm-body"> <label for="headingShareInput" class="form-label small text-muted mb-1 text-uppercase fw-bold" style="font-size: 0.7rem; letter-spacing: 0.5px;">Permalink</label> <div class="input-group mb-4 hsm-url-group"> <input id="headingShareInput" type="text" class="form-control font-monospace" readonly aria-readonly="true" style="font-size: 0.85rem;" /> <button class="btn btn-primary hsm-copy" type="button" aria-label="Copy" title="Copy"> </button> </div> <div class="small fw-bold mb-2 text-muted text-uppercase" style="font-size: 0.7rem; 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Understanding deletion semantics is crucial for maintaining data integrity, as improper deletion can orphan data or violate referential constraints. Geode implements the DELETE clause according to the ISO/IEC 39075:2024 GQL standard with additional safety features. <h3 id="introduction-to-delete" class="position-relative d-flex align-items-center group"> Introduction to 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="introduction-to-delete" aria-haspopup="dialog" aria-label="Share link: Introduction to DELETE"> Share link </button> </h3>Deletion in graph databases differs from relational databases because of the interconnected nature of graph data. When you delete a node, you must consider what happens to its relationships. Geode provides multiple deletion modes to handle these scenarios safely. Key characteristics of DELETE: <ul> <li>Referential Integrity: Nodes with relationships cannot be deleted without explicitly handling those relationships</li> <li>DETACH DELETE: Automatically removes relationships when deleting nodes</li> <li>Selective Deletion: Delete specific elements matched by patterns</li> <li>Transaction Safety: Deletions are atomic and can be rolled back</li> <li>Cascading Behavior: Control over how deletion propagates through the graph</li> </ul> <h3 id="deleting-relationships" class="position-relative d-flex align-items-center group"> Deleting Relationships <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="deleting-relationships" aria-haspopup="dialog" aria-label="Share link: Deleting Relationships"> Share link </button> </h3> <h4 id="basic-relationship-deletion" class="position-relative d-flex align-items-center group"> Basic Relationship Deletion <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-relationship-deletion" aria-haspopup="dialog" aria-label="Share link: Basic Relationship Deletion"> Share link </button> </h4>Delete relationships while keeping the connected nodes intact. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete a specific relationship MATCH (a:Person {name: 'Alice'})-[r:FRIENDS_WITH]->(b:Person {name: 'Bob'}) DELETE r; -- Delete all relationships of a type MATCH ()-[r:TEMPORARY]-() DELETE r; -- Delete relationships with specific properties MATCH (a:User)-[r:FOLLOWS]->(b:User) WHERE r.since < date('2020-01-01') DELETE r; </code></pre></div> <h4 id="deleting-multiple-relationships" class="position-relative d-flex align-items-center group"> Deleting Multiple Relationships <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="deleting-multiple-relationships" aria-haspopup="dialog" aria-label="Share link: Deleting Multiple Relationships"> Share link </button> </h4>Remove multiple relationships in a single operation. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete all relationships between two nodes MATCH (a:Person {name: 'Alice'})-[r]-(b:Person {name: 'Bob'}) DELETE r; -- Delete relationships matching a pattern MATCH (u:User)-[r:LIKED|VIEWED]->(p:Post) WHERE p.archived = true DELETE r; -- Delete all outgoing relationships from a node MATCH (u:User {id: $user_id})-[r]->() DELETE r; </code></pre></div> <h4 id="conditional-relationship-deletion" class="position-relative d-flex align-items-center group"> Conditional Relationship Deletion <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-relationship-deletion" aria-haspopup="dialog" aria-label="Share link: Conditional Relationship Deletion"> Share link </button> </h4>Delete relationships based on complex conditions. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete inactive connections MATCH (a:User)-[r:CONNECTED_TO]->(b:User) WHERE r.last_interaction < datetime() - duration('P90D') DELETE r; -- Delete weak relationships MATCH (a:Person)-[r:KNOWS]->(b:Person) WHERE r.strength < 0.3 DELETE r RETURN count(r) AS deleted_count; </code></pre></div> <h3 id="deleting-nodes" class="position-relative d-flex align-items-center group"> Deleting Nodes <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="deleting-nodes" aria-haspopup="dialog" aria-label="Share link: Deleting Nodes"> Share link </button> </h3> <h4 id="basic-node-deletion" class="position-relative d-flex align-items-center group"> Basic Node Deletion <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-node-deletion" aria-haspopup="dialog" aria-label="Share link: Basic Node Deletion"> Share link </button> </h4>Delete nodes that have no relationships. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete a node without relationships MATCH (n:TempNode {id: $id}) DELETE n; -- Delete orphaned nodes MATCH (n:DataPoint) WHERE NOT (n)--() DELETE n; </code></pre></div> <h4 id="node-deletion-constraint" class="position-relative d-flex align-items-center group"> Node Deletion Constraint <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-deletion-constraint" aria-haspopup="dialog" aria-label="Share link: Node Deletion Constraint"> Share link </button> </h4>Attempting to delete a node with relationships raises an error. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- This will fail if Alice has any relationships MATCH (p:Person {name: 'Alice'}) DELETE p; -- Error: Cannot delete node with relationships -- First remove relationships, then delete MATCH (p:Person {name: 'Alice'})-[r]-() DELETE r; MATCH (p:Person {name: 'Alice'}) DELETE p; </code></pre></div> <h4 id="detach-delete" class="position-relative d-flex align-items-center group"> DETACH 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="detach-delete" aria-haspopup="dialog" aria-label="Share link: DETACH DELETE"> Share link </button> </h4>DETACH DELETE removes a node and all its relationships in one operation. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete node and all its relationships MATCH (p:Person {name: 'Alice'}) DETACH DELETE p; -- Delete multiple nodes with their relationships MATCH (p:Product) WHERE p.discontinued = true DETACH DELETE p; -- Delete user and all their activity MATCH (u:User {id: $user_id}) DETACH DELETE u; </code></pre></div> <h3 id="deleting-by-pattern" class="position-relative d-flex align-items-center group"> Deleting by 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="deleting-by-pattern" aria-haspopup="dialog" aria-label="Share link: Deleting by Pattern"> Share link </button> </h3> <h4 id="pattern-based-deletion" class="position-relative d-flex align-items-center group"> Pattern-Based Deletion <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-based-deletion" aria-haspopup="dialog" aria-label="Share link: Pattern-Based Deletion"> Share link </button> </h4>Delete elements that match specific graph patterns. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete posts and their comments MATCH (p:Post {id: $post_id})-[:HAS_COMMENT]->(c:Comment) DETACH DELETE p, c; -- Delete a chain of nodes MATCH (start:Node {id: $id})-[:NEXT*]->(following:Node) DETACH DELETE start, following; -- Delete nodes in a specific subgraph MATCH (project:Project {id: $project_id}) MATCH (project)-[:CONTAINS]->(task:Task) MATCH (task)-[:HAS_SUBTASK]->(subtask:Subtask) DETACH DELETE project, task, subtask; </code></pre></div> <h4 id="selective-pattern-deletion" class="position-relative d-flex align-items-center group"> Selective Pattern Deletion <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="selective-pattern-deletion" aria-haspopup="dialog" aria-label="Share link: Selective Pattern Deletion"> Share link </button> </h4>Delete only specific elements from matched patterns. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete only intermediate nodes MATCH (a:User)-[:AUTHORED]->(draft:Draft)-[:REVISION_OF]->(published:Post) DETACH DELETE draft; -- Delete relationship but keep nodes MATCH (a:Person)-[r:BLOCKED]->(b:Person) DELETE r; </code></pre></div> <h3 id="bulk-deletion" class="position-relative d-flex align-items-center group"> Bulk Deletion <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="bulk-deletion" aria-haspopup="dialog" aria-label="Share link: Bulk Deletion"> Share link </button> </h3> <h4 id="deleting-many-nodes" class="position-relative d-flex align-items-center group"> Deleting Many Nodes <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="deleting-many-nodes" aria-haspopup="dialog" aria-label="Share link: Deleting Many Nodes"> Share link </button> </h4>Efficiently delete large numbers of nodes. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete all nodes of a label MATCH (n:TempData) DETACH DELETE n; -- Delete in batches (application pattern) MATCH (n:LogEntry) WHERE n.timestamp < datetime() - duration('P30D') WITH n LIMIT 10000 DETACH DELETE n RETURN count(n) AS deleted; -- Repeat until deleted = 0 </code></pre></div> <h4 id="time-based-cleanup" class="position-relative d-flex align-items-center group"> Time-Based Cleanup <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-based-cleanup" aria-haspopup="dialog" aria-label="Share link: Time-Based Cleanup"> Share link </button> </h4>Delete data based on age or timestamps. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete old sessions MATCH (s:Session) WHERE s.expires_at < datetime() DETACH DELETE s; -- Delete old events MATCH (e:Event) WHERE e.created_at < datetime() - duration('P1Y') DETACH DELETE e RETURN count(e) AS deleted_events; </code></pre></div> <h4 id="conditional-bulk-deletion" class="position-relative d-flex align-items-center group"> Conditional Bulk Deletion <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-bulk-deletion" aria-haspopup="dialog" aria-label="Share link: Conditional Bulk Deletion"> Share link </button> </h4>Delete based on complex business rules. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete inactive users with no content MATCH (u:User) WHERE u.last_login < datetime() - duration('P2Y') AND NOT (u)-[:AUTHORED]->(:Post) AND NOT (u)-[:COMMENTED]->(:Comment) DETACH DELETE u; -- Delete products with no orders MATCH (p:Product) WHERE NOT (p)<-[:CONTAINS]-(:Order) AND p.created_at < datetime() - duration('P1Y') DETACH DELETE p; </code></pre></div> <h3 id="removing-properties" class="position-relative d-flex align-items-center group"> Removing 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="removing-properties" aria-haspopup="dialog" aria-label="Share link: Removing Properties"> Share link </button> </h3> <h4 id="remove-for-properties" class="position-relative d-flex align-items-center group"> REMOVE for 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="remove-for-properties" aria-haspopup="dialog" aria-label="Share link: REMOVE for Properties"> Share link </button> </h4>Use REMOVE to delete properties from nodes or relationships (alternative to SET … = null). <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Remove a property MATCH (p:Person {name: 'Alice'}) REMOVE p.temporary_field; -- Remove multiple properties MATCH (p:Product) WHERE p.discontinued = true REMOVE p.price, p.inventory_count; -- Remove property from relationship MATCH (a:User)-[r:FOLLOWS]->(b:User) WHERE r.muted = true REMOVE r.muted; </code></pre></div> <h4 id="using-set-with-null" class="position-relative d-flex align-items-center group"> Using SET with NULL <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="using-set-with-null" aria-haspopup="dialog" aria-label="Share link: Using SET with NULL"> Share link </button> </h4>An alternative way to remove properties. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Set property to null (removes it) MATCH (p:Person {name: 'Alice'}) SET p.deprecated_field = null; -- Clear optional properties MATCH (u:User {id: $user_id}) SET u.phone = null, u.secondary_email = null; </code></pre></div> <h4 id="removing-labels" class="position-relative d-flex align-items-center group"> Removing Labels <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="removing-labels" aria-haspopup="dialog" aria-label="Share link: Removing Labels"> Share link </button> </h4>Remove labels from nodes. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Remove a label MATCH (e:Employee:Contractor {id: $id}) REMOVE e:Contractor; -- Remove temporary labels MATCH (n:Flagged) WHERE n.reviewed = true REMOVE n:Flagged; </code></pre></div> <h3 id="safe-deletion-patterns" class="position-relative d-flex align-items-center group"> Safe Deletion 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="safe-deletion-patterns" aria-haspopup="dialog" aria-label="Share link: Safe Deletion Patterns"> Share link </button> </h3> <h4 id="check-before-delete" class="position-relative d-flex align-items-center group"> Check Before 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="check-before-delete" aria-haspopup="dialog" aria-label="Share link: Check Before Delete"> Share link </button> </h4>Verify conditions before deleting. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Check for dependencies before delete MATCH (p:Project {id: $project_id}) OPTIONAL MATCH (p)-[:HAS_TASK]->(t:Task) WITH p, count(t) AS task_count WHERE task_count = 0 DETACH DELETE p RETURN CASE WHEN p IS NULL THEN 'Nothing deleted' ELSE 'Project deleted' END; </code></pre></div> <h4 id="soft-delete-pattern" class="position-relative d-flex align-items-center group"> Soft Delete Pattern <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="soft-delete-pattern" aria-haspopup="dialog" aria-label="Share link: Soft Delete Pattern"> Share link </button> </h4>Mark as deleted instead of removing. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Soft delete: mark as deleted MATCH (u:User {id: $user_id}) SET u.deleted = true, u.deleted_at = datetime(); -- Query excludes soft-deleted MATCH (u:User) WHERE u.deleted IS NULL OR u.deleted = false RETURN u; -- Hard delete after retention period MATCH (u:User) WHERE u.deleted = true AND u.deleted_at < datetime() - duration('P90D') DETACH DELETE u; </code></pre></div> <h4 id="archive-before-delete" class="position-relative d-flex align-items-center group"> Archive Before 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="archive-before-delete" aria-haspopup="dialog" aria-label="Share link: Archive Before Delete"> Share link </button> </h4>Create an archive before deletion. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Archive user data before deletion MATCH (u:User {id: $user_id}) CREATE (a:ArchivedUser { original_id: u.id, name: u.name, email: u.email, archived_at: datetime() }) WITH u, a MATCH (u)-[r:AUTHORED]->(p:Post) CREATE (a)-[:ARCHIVED_POST]->(:ArchivedPost { title: p.title, created_at: p.created_at }) WITH u DETACH DELETE u; </code></pre></div> <h4 id="transaction-safe-deletion" class="position-relative d-flex align-items-center group"> Transaction-Safe Deletion <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-safe-deletion" aria-haspopup="dialog" aria-label="Share link: Transaction-Safe Deletion"> Share link </button> </h4>Use transactions for complex deletions. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Within a transaction (pseudo-code showing concept) BEGIN TRANSACTION; -- Step 1: Verify no active orders MATCH (c:Customer {id: $customer_id})-[:PLACED]->(o:Order) WHERE o.status IN ['pending', 'processing'] WITH count(o) AS active_orders WHERE active_orders > 0 THROW 'Cannot delete customer with active orders'; -- Step 2: Archive orders MATCH (c:Customer {id: $customer_id})-[:PLACED]->(o:Order) SET o.customer_archived = true; -- Step 3: Delete customer MATCH (c:Customer {id: $customer_id}) DETACH DELETE c; COMMIT; </code></pre></div> <h3 id="cascading-deletion" class="position-relative d-flex align-items-center group"> Cascading Deletion <button type="button" class="h-share btn btn-link p-0 text-decoration-none link-secondary opacity-50 hover-opacity-100 transition-all ms-1" data-share-target="cascading-deletion" aria-haspopup="dialog" aria-label="Share link: Cascading Deletion"> Share link </button> </h3> <h4 id="manual-cascade" class="position-relative d-flex align-items-center group"> Manual Cascade <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="manual-cascade" aria-haspopup="dialog" aria-label="Share link: Manual Cascade"> Share link </button> </h4>Explicitly delete related elements in order. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete project with all nested content MATCH (project:Project {id: $project_id}) -- First delete deepest level OPTIONAL MATCH (project)-[:CONTAINS]->(task:Task)-[:HAS_COMMENT]->(comment:Comment) DETACH DELETE comment -- Then delete tasks WITH project OPTIONAL MATCH (project)-[:CONTAINS]->(task:Task) DETACH DELETE task -- Finally delete project WITH project DETACH DELETE project; </code></pre></div> <h4 id="recursive-deletion" class="position-relative d-flex align-items-center group"> Recursive Deletion <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-deletion" aria-haspopup="dialog" aria-label="Share link: Recursive Deletion"> Share link </button> </h4>Delete hierarchical structures. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete category and subcategories MATCH (c:Category {id: $category_id}) CALL { WITH c MATCH (c)-[:PARENT_OF*0..]->(sub:Category) RETURN sub } DETACH DELETE sub; </code></pre></div> <h4 id="handling-shared-relationships" class="position-relative d-flex align-items-center group"> Handling Shared Relationships <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="handling-shared-relationships" aria-haspopup="dialog" aria-label="Share link: Handling Shared Relationships"> Share link </button> </h4>Be careful with nodes that have multiple parents. <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Delete tag only if no other posts reference it MATCH (p:Post {id: $post_id})-[r:TAGGED]->(t:Tag) DELETE r WITH t WHERE NOT (t)<-[:TAGGED]-() DELETE t; </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="safety-guidelines" class="position-relative d-flex align-items-center group"> Safety 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="safety-guidelines" aria-haspopup="dialog" aria-label="Share link: Safety Guidelines"> Share link </button> </h4><ol> <li>Test in Development First: Always test deletion queries on non-production data</li> </ol> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Use RETURN first to verify what will be deleted MATCH (n:OldData) WHERE n.created < date('2020-01-01') RETURN n.id, n.name, n.created LIMIT 100; -- Then change RETURN to DETACH DELETE </code></pre></div><ol start="2"> <li>Use Transactions: Wrap complex deletions in transactions</li> </ol> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">BEGIN; -- Multiple delete operations MATCH (a:TypeA) DETACH DELETE a; MATCH (b:TypeB) DETACH DELETE b; -- If anything fails, rollback COMMIT; </code></pre></div><ol start="3"> <li>Limit Batch Sizes: For large deletions, process in batches</li> </ol> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Application loop pattern CALL { MATCH (n:ExpiredData) WHERE n.expires < datetime() WITH n LIMIT 1000 DETACH DELETE n RETURN count(n) AS deleted }; </code></pre></div> <h4 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> </h4><ol> <li>Index Before Delete: Ensure filter properties are indexed</li> </ol> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">CREATE INDEX data_timestamp ON Data(timestamp); -- Faster deletion MATCH (d:Data) WHERE d.timestamp < $cutoff DETACH DELETE d; </code></pre></div><ol start="2"> <li>Avoid Full Scans: Use specific patterns</li> </ol> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Good: Uses index MATCH (u:User {email: $email}) DETACH DELETE u; -- Avoid: Full scan MATCH (u:User) WHERE u.email = $email DETACH DELETE u; -- Only if email is not indexed </code></pre></div><ol start="3"> <li>Monitor Deletion Progress: Return counts for visibility</li> </ol> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">MATCH (n:TempData) WITH n LIMIT 10000 DETACH DELETE n RETURN count(n) AS deleted_count; </code></pre></div> <h4 id="data-protection" class="position-relative d-flex align-items-center group"> Data Protection <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-protection" aria-haspopup="dialog" aria-label="Share link: Data Protection"> Share link </button> </h4><ol> <li>Backup Before Mass Deletion: Export data before large deletions</li> <li>Use Soft Deletes for Important Data: Enable recovery</li> <li>Audit Deletions: Log what was deleted and by whom</li> </ol> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Create audit log entry MATCH (u:User {id: $user_id}) CREATE (audit:AuditLog { action: 'DELETE_USER', target_id: u.id, target_name: u.name, deleted_by: $admin_id, deleted_at: datetime() }) WITH u DETACH DELETE u; </code></pre></div> <h3 id="common-errors" class="position-relative d-flex align-items-center group"> Common 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-errors" aria-haspopup="dialog" aria-label="Share link: Common Errors"> Share link </button> </h3> <h4 id="cannot-delete-node-with-relationships" class="position-relative d-flex align-items-center group"> Cannot Delete Node with Relationships <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="cannot-delete-node-with-relationships" aria-haspopup="dialog" aria-label="Share link: Cannot Delete Node with Relationships"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Error: Cannot delete node<123>, because it still has relationships MATCH (n:Node {id: 123}) DELETE n; -- Solution: Use DETACH DELETE MATCH (n:Node {id: 123}) DETACH DELETE n; </code></pre></div> <h4 id="nothing-deleted" class="position-relative d-flex align-items-center group"> Nothing Deleted <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="nothing-deleted" aria-haspopup="dialog" aria-label="Share link: Nothing Deleted"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- Returns 0 if node not found MATCH (n:Node {id: 'nonexistent'}) DELETE n RETURN count(n) AS deleted; -- Result: deleted = 0 </code></pre></div> <h4 id="accidental-mass-deletion" class="position-relative d-flex align-items-center group"> Accidental Mass Deletion <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="accidental-mass-deletion" aria-haspopup="dialog" aria-label="Share link: Accidental Mass Deletion"> Share link </button> </h4><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-gql" data-lang="gql">-- DANGER: Deletes ALL nodes of label MATCH (n:User) DETACH DELETE n; -- Probably not what you wanted! -- Safe: Always use specific conditions MATCH (n:User {status: 'deleted'}) DETACH DELETE n; </code></pre></div> <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/create/" >CREATE Clause</a> : Creating nodes and relationships</li> <li><a href="/tags/set/" >SET Clause</a> : Updating properties instead of deleting</li> <li><a href="/tags/match/" >MATCH Clause</a> : Finding elements to delete</li> <li><a href="/tags/where/" >WHERE Clause</a> : Filtering deletion targets</li> <li><a href="/tags/transactions/" >Transactions</a> : Atomic deletion operations</li> <li><a href="/tags/gql-reference/" >GQL Reference</a> : Complete GQL language reference</li> <li><a href="/tags/data-modeling/" >Data Modeling</a> : Designing for deletion</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>GQL Tutorial - Deleting Data: <code>/docs/gql-tutorial/deleting-data/</code></li> <li>Data Lifecycle Management: <code>/docs/operations/data-lifecycle/</code></li> <li>Backup and Recovery: <code>/docs/recovery/backup-restore/</code></li> <li>Transaction Guide: <code>/docs/transactions/overview/</code></li> <li>Best Practices: <code>/docs/guides/best-practices/</code></li> </ul>

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