==================================== Counting all rows in a table is slow

Audience: ScyllaDB users

Trying to count all rows in a table using

.. code-block:: cql

SELECT COUNT(1) FROM ks.table;

may fail with the ReadTimeout error.

COUNT() runs a full-scan query on all nodes, which might take a long time to finish. As a result, the count time may be greater than the ScyllaDB query timeout. One way to prevent that issue in ScyllaDB 4.4 or later is to increase the timeout for the query using the :ref:USING TIMEOUT <using-timeout> directive, for example:

.. code-block:: cql

SELECT COUNT(1) FROM ks.table USING TIMEOUT 120s;

You can also get an estimation of the number of partitions (not rows) with :doc:nodetool tablestats </operating-scylla/nodetool-commands/tablestats>.

.. note:: ScyllaDB 5.1 includes improvements to speed up the execution of SELECT COUNT(*) queries. To increase the count speed, we recommend upgrading to ScyllaDB 5.1 or later.

.. REMOVE IN FUTURE VERSIONS - Remove the note above in version 5.1.