query_iterator()

This operation returns a Python iterator for you to iterate over the query results. It is useful especially when the query result contains a large volume of data.

Request Syntax

query_iterator(
    batch_size: int, 
    limit: int, 
    expr: str | None, 
    output_fields: list[str] | None, 
    partition_names: list[str] | None, 
    timeout: float | None
)

PARAMETERS:

batch_size (int)

The number of entities to return each time you call next() on the current iterator.

The value defaults to 1000. Set it to a proper value to control the number of entities to return per iteration.
limit (int)

The total number of entities to return.

The value defaults to -1, indicating all matching entities will be in return.
expr (str)

A scalar filtering condition to filter matching entities.

The value defaults to None, indicating that scalar filtering is ignored. To build a scalar filtering condition, refer to Boolean Expression Rules.
output_fields (list)

A list of field names to include in each entity in return.

The value defaults to None. If left unspecified, only the primary field is included.
partition_names (list)

A list of partition names.

The value defaults to None. If specified, only the specified partitions are involved in queries.
timeout (float)

The timeout duration for this operation. Setting this to None indicates that this operation timeouts when any response arrives or any error occurs.

RETURN TYPE:

QueryIterator

RETURNS:

A QueryIterator for you to iterate over the query result.

EXCEPTIONS:

MilvusException

This exception will be raised when any error occurs during this operation.

Examples

from pymilvus import Collection, CollectionSchema, FieldSchema, DataType

schema = CollectionSchema([
    FieldSchema("id", DataType.INT64, is_primary=True),
    FieldSchema("vector", DataType.FLOAT_VECTOR, dim=5)
])

# Create a collection
collection = Collection(
    name="test_collection",
    schema=schema
)

# Insert a list of columns
res = collection.insert(
    data=[
        [0,1,2,3,4,5,6,7,8,9],               # id
        [                                    # vector
            [0.1,0.2,-0.3,-0.4,0.5],
            [0.3,-0.1,-0.2,-0.6,0.7],
            [-0.6,-0.3,0.2,0.8,0.7],
            [0.6,0.2,-0.3,-0.8,0.5],
            [0.3,0.1,-0.2,-0.6,-0.7],
            [0.1,0.2,-0.3,-0.4,0.5],
            [0.3,-0.1,-0.2,-0.6,0.7],
            [-0.6,-0.3,0.2,0.8,0.7],
            [0.6,0.2,-0.3,-0.8,0.5],
            [0.3,0.1,-0.2,-0.6,-0.7],
        ],
    ]
)

# Create a query iterator
iterator = collection.query_iterator(
    batch_size=2,
    limit=10,
    expr="id > 3",
    output_fields=["id", "vector"]
)

# Start iterating
while True:
    res = iterator.next()
    
    if not res:
        res.close()
        break

Related operations

The following operations are related to query_iterator():