apache/cassandra · error · RuntimeException

You must supply a keyspace name

Error message

You must supply a keyspace name

What it means

parseEntitiesForSnapshot parses 'keyspace.table' entity strings and throws RuntimeException('You must supply a keyspace name') when the keyspace part is null. In practice the split already guaranteed two tokens, so this guards a null/empty keyspace name supplied to the snapshot entity parser before Keyspace.getValidKeyspace is called. Note that a present-but-missing keyspace is instead rejected later by getValidKeyspace.

Solutions

1. Supply entities in 'keyspace.table' form with a non-empty keyspace name.
2. Verify the calling script's keyspace variable is set and non-empty before invoking the snapshot.
3. Prefer nodetool snapshot CLI parsing, which validates entity format before reaching this code.

Example fix

// before
String entity = ".users"; // empty keyspace part
// after
String entity = "keyspace1.users";

if (entity == null || entity.indexOf('.') <= 0)
    throw new IllegalArgumentException("Entity must be keyspace.table: " + entity);
String ks = entity.substring(0, entity.indexOf('.'));
if (ks.isEmpty()) throw new IllegalArgumentException("Empty keyspace in entity " + entity);

try { takeSnapshot(entities); } catch (RuntimeException e) { if (e.getMessage().equals("You must supply a keyspace name")) throw new IllegalArgumentException("Malformed entity: " + entities, e); throw e; }

When it happens

Trigger: Calling the snapshot API/StorageService.takeSnapshot with entity strings lacking a keyspace portion (null keyspace token reaching this branch), e.g. passing malformed entity arguments programmatically via JMX.

Common situations: JMX/console invocations constructing entity strings manually instead of via nodetool parsing; scripts building 'keyspace.table' pairs where the keyspace variable is unset/null.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Cannot take a snapshot on secondary index or invalid column…
• You must supply a table name
• A range supplied to SSTableCursorReader ends before it…
• Argument must have keyspace and table values.
• arguments for -F are json, yaml, table only.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/77345f0b922f6b7e. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/service/snapshot/TakeSnapshotTask.java:210

        snapshotToCreate.complete();
    }

    private Set<ColumnFamilyStore> parseEntitiesForSnapshot(String... entities)
    {
        Set<ColumnFamilyStore> entitiesForSnapshot = new HashSet<>();

        if (entities != null && entities.length > 0 && entities[0].contains("."))
        {
            for (String entity : entities)
            {
                String[] splitted = StringUtils.split(entity, '.');
                if (splitted.length == 2)
                {
                    String keyspaceName = splitted[0];
                    String tableName = splitted[1];

                    if (keyspaceName == null)
                        throw new RuntimeException("You must supply a keyspace name");
                    if (tableName == null)
                        throw new RuntimeException("You must supply a table name");

                    Keyspace validKeyspace = Keyspace.getValidKeyspace(keyspaceName);
                    ColumnFamilyStore existingTable = validKeyspace.getColumnFamilyStore(tableName);

                    entitiesForSnapshot.add(existingTable);
                }
                // special case for index which we can not normally create a snapshot for
                // but a snapshot is apparently taken before a secondary index is scrubbed,
                // so we preserve this behavior
                else if (splitted.length == 3)
                {
                    String keyspaceName = splitted[0];
                    String tableName = splitted[1];

                    Keyspace validKeyspace = Keyspace.getValidKeyspace(keyspaceName);
                    ColumnFamilyStore existingTable = validKeyspace.getColumnFamilyStore(tableName);

View on GitHub (pinned to 88fd0f6a0e)