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Understanding Deletes in Append-Only Storage

OnDB performs soft deletes. When you delete a document, a new record with deleted: true is appended. The original data is preserved but excluded from query results by default.

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Delete Pattern

Soft delete a document by finding it and storing a new version with deleted: true.
TypeScript
// Find the document
const user = await client.queryBuilder()
  .collection('users')
  .whereField('email').equals('alice@example.com')
  .executeUnique();

if (user) {
  // Store soft-deleted version
  await client.store(
    { collection: 'users', data: [{ ...user, deleted: true, deletedAt: new Date().toISOString() }] },
    async (quote) => {
      const txHash = await processPayment(quote);
      return { txHash, network: quote.network, sender: walletAddress, chainType: quote.chainType, paymentMethod: 'native' };
    },
    true
  );
  console.log('Deleted user');
} else {
  console.log('User not found');
}

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How Deletes Work

Original Record (Block 100):
{ id: "user_1", name: "Alice", email: "alice@example.com", deleted: false }

After Delete (Block 101):
{ id: "user_1", deleted: true, deletedAt: "2024-01-02", updatedAt: "2024-01-02" }

Original record is preserved, but queries exclude deleted records

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Examples

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Delete by ID

TypeScript
const post = await client.queryBuilder()
  .collection('posts')
  .whereField('id').equals('post_123')
  .executeUnique();

if (post) {
  await client.store(
    { collection: 'posts', data: [{ ...post, deleted: true, deletedAt: new Date().toISOString() }] },
    paymentCallback,
    true
  );
  console.log('Post deleted successfully');
} else {
  console.log('Post not found');
}

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Conditional Delete Pattern

TypeScript
// First verify ownership or permissions
const post = await client.queryBuilder()
  .collection('posts')
  .whereField('id').equals('post_123')
  .executeUnique();

if (post && post.author === currentUser.id) {
  await client.store(
    { collection: 'posts', data: [{ ...post, deleted: true, deletedAt: new Date().toISOString() }] },
    paymentCallback,
    true
  );
  console.log('Post deleted');
} else {
  console.log('Unauthorized or not found');
}

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Verifying Deletion

After deletion, the document won’t appear in normal queries:
TypeScript
// Delete a user
const user = await client.queryBuilder()
  .collection('users')
  .whereField('id').equals('user_123')
  .executeUnique();

if (user) {
  await client.store(
    { collection: 'users', data: [{ ...user, deleted: true, deletedAt: new Date().toISOString() }] },
    paymentCallback,
    true
  );
}

// executeUnique returns null for deleted documents
const deleted = await client.queryBuilder()
  .collection('users')
  .whereField('id').equals('user_123')
  .executeUnique();
console.log(deleted); // null

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Data Retention

Since OnDB uses append-only storage:
AspectBehavior
Original dataRemains on blockchain permanently
Query resultsExclude deleted records by default
Audit trailFull history is preserved
RecoveryPossible by querying historical records

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Bulk Delete Pattern

For deleting multiple documents, query and delete each:
TypeScript
const result = await client.queryBuilder()
  .collection('users')
  .whereField('active').isFalse()
  .execute();

for (const user of result.records) {
  await client.store(
    { collection: 'users', data: [{ ...user, deleted: true, deletedAt: new Date().toISOString() }] },
    paymentCallback,
    true
  );
}

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Next Steps

CRUD Overview

Back to CRUD overview

Query Builder

Complex queries