Data Operations - Delete

This guide covers deleting data from Milvus collections.

Delete by IDs

Delete entities by their primary key IDs:

await client.delete({
  collection_name: 'my_collection',
  ids: [1, 2, 3, 4, 5],
});

Delete with String IDs

For VarChar primary keys:

await client.delete({
  collection_name: 'my_collection',
  ids: ['id1', 'id2', 'id3'],
});

Delete by Filter Expression

Delete entities matching a filter expression:

await client.delete({
  collection_name: 'my_collection',
  filter: 'age < 18',
});

Or using expr:

await client.delete({
  collection_name: 'my_collection',
  expr: 'age < 18 AND category == "old"',
});

Delete Entities (Advanced)

Use deleteEntities for more control:

await client.deleteEntities({
  collection_name: 'my_collection',
  expr: 'age < 18',
});

Delete Response

Delete operations return mutation results:

const result = await client.delete({
  collection_name: 'my_collection',
  ids: [1, 2, 3],
});

console.log('Delete count:', result.delete_cnt);
console.log('IDs:', result.IDs);
console.log('Timestamp:', result.timestamp);

Delete from Specific Partition

Delete entities from a specific partition:

await client.delete({
  collection_name: 'my_collection',
  partition_name: 'partition_1',
  ids: [1, 2, 3],
});

Filter Expressions for Delete

Use the same filter expression syntax as queries:

Comparison Operators

'age > 25'
'age >= 25'
'age < 25'
'age <= 25'
'age == 25'
'age != 25'

Logical Operators

'age > 25 AND category == "tech"'
'age > 25 OR age < 18'
'NOT (age > 25)'

In Operator

'id in [1, 2, 3, 4, 5]'
'category in ["old", "deprecated"]'

String Operations

'text like "%deprecated%"'

Batch Deletion

Delete large numbers of entities efficiently:

// Delete by IDs in batches
const idsToDelete = [/* large array of IDs */];
const batchSize = 1000;

for (let i = 0; i < idsToDelete.length; i += batchSize) {
  const batch = idsToDelete.slice(i, i + batchSize);
  await client.delete({
    collection_name: 'my_collection',
    ids: batch,
  });
}

Flush After Delete

Flush to ensure deletions are persisted:

await client.delete({
  collection_name: 'my_collection',
  ids: [1, 2, 3],
});

// Flush to persist deletions
await client.flush({
  collection_names: ['my_collection'],
});

Error Handling

Handle deletion errors:

try {
  await client.delete({
    collection_name: 'my_collection',
    ids: [1, 2, 3],
  });
} catch (error) {
  if (error.message.includes('CollectionNotExists')) {
    console.error('Collection does not exist');
  } else if (error.message.includes('IllegalArgument')) {
    console.error('Invalid delete parameters');
  } else {
    console.error('Delete failed:', error);
  }
}

Delete Best Practices

1. Use filters for bulk deletion: Use filter expressions for deleting many entities
2. Use IDs for specific deletion: Use IDs when deleting specific entities
3. Flush after deletion: Always flush after deletions to ensure persistence
4. Batch operations: Delete in batches for large deletions
5. Verify before delete: Query first to verify what will be deleted
6. Use transactions: Consider using transactions for related deletions

Complete Example

import { MilvusClient, DataType } from '@zilliz/milvus2-sdk-node';

const client = new MilvusClient({
  address: 'localhost:19530',
});

await client.connectPromise;

// Delete by IDs
const deleteResult = await client.delete({
  collection_name: 'my_collection',
  ids: [1, 2, 3],
});

console.log('Deleted:', deleteResult.delete_cnt);

// Delete by filter
await client.delete({
  collection_name: 'my_collection',
  expr: 'age < 18',
});

// Flush to persist
await client.flush({
  collection_names: ['my_collection'],
});

// Verify deletion
const count = await client.count({
  collection_name: 'my_collection',
  expr: 'age < 18',
});

console.log('Remaining entities:', count.data);

Next Steps

• Learn about Data Management
• Explore Query Operations
• Check out Best Practices