apache/cassandra · error · InvalidRequestException

The specified table is read-only.

Error message

The specified table is read-only.

What it means

Virtual table PartitionKeyStatsTable.truncate always throws InvalidRequestException(TABLE_READ_ONLY_ERROR): virtual tables are backed by in-memory runtime state, not mutable data, so TRUNCATE against them is rejected by design. Any write path (apply) is similarly rejected.

Source

Thrown at src/java/org/apache/cassandra/db/virtual/PartitionKeyStatsTable.java:358

        return BufferCell.live(column, 1L, value);
    }

    @Override
    public TableMetadata metadata()
    {
        return this.metadata;
    }

    @Override
    public UnfilteredPartitionIterator select(DataRange dataRange, ColumnFilter columnFilter, RowFilter rowFilter, DataLimits limits)
    {
        throw new InvalidRequestException(UNSUPPORTED_RANGE_QUERY_ERROR);
    }

    @Override
    public void truncate()
    {
        throw new InvalidRequestException(TABLE_READ_ONLY_ERROR);
    }

    @Override
    public void apply(PartitionUpdate update)
    {
        throw new InvalidRequestException(TABLE_READ_ONLY_ERROR);
    }
}

View on GitHub (pinned to 88fd0f6a0e)

Solutions

  1. Remove the TRUNCATE; virtual tables cannot be truncated.
  2. Exclude virtual keyspaces (system_views, system_settings) from maintenance scripts.
  3. Reset the underlying runtime state (e.g. via nodetool) if the goal is clearing reflected data.

Example fix

// before
TRUNCATE system_views.partitions;
// after
// no-op: read-only virtual table; filter it out of cleanup scripts
Defensive patterns

Strategy: validation

Validate before calling

// Exclude virtual tables from any truncate list
Set<String> virtualTables = session.execute("SELECT keyspace_name, table_name FROM system_schema.virtual_tables")
    .all().stream().map(r -> r.getString(0)+"."+r.getString(1)).collect(Collectors.toSet());
if (virtualTables.contains(ks+"."+table)) throw new IllegalStateException("refusing to truncate virtual table");

Try / catch

try { session.execute("TRUNCATE system_views.partitions"); }
catch (com.datastax.oss.driver.api.core.servererrors.InvalidQueryException e) {
    if (e.getMessage().contains("read-only")) { /* skip virtual table */ }
    else throw e;
}

Prevention

When it happens

Trigger: `TRUNCATE system_views.partitions;` or tooling that resets table contents including virtual keyspaces.

Common situations: Cleanup scripts iterating all keyspaces; test teardown code clearing system_views tables.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/b2beab50cf7e2531. Report an issue: GitHub.