# Cassandra Storage Engine Issues

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The Cassandra storage engine was removed in MariaDB 10.6.
{% endhint %}

This page lists difficulties and peculiarities of [Cassandra Storage Engine](https://mariadb.com/docs/server/server-usage/storage-engines/legacy-storage-engines/cassandra/cassandra-storage-engine-overview). I'm not putting them into bug tracker because it is not clear whether these properties should be considered bugs.

## No way to get E(#rows in column family)

There seems to be no way to get even a rough estimate of how many different keys are present in a column family. I'm using an arbitrary value of 1000 now, which causes

* EXPLAIN will always show rows=1000 for full table scans. In the future, this may cause poor query plans.
* `DELETE FROM table` always prints "1000 rows affected", with no regards how many records were actually there in the table.

```
MariaDB [j1]> delete from t1;
Query OK, 1000 rows affected (0.14 sec)
```

We could use the new [engine-independent-table-statistics](https://mariadb.com/docs/server/ha-and-performance/optimization-and-tuning/query-optimizations/statistics-for-optimizing-queries/engine-independent-table-statistics) feature to get some data statistics.

<sub>*This page is licensed: CC BY-SA / Gnu FDL*</sub>

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