apache/cassandra · error · ConfigurationException

Missing sub-option ' ' for the ' ' option

Error message

Missing sub-option '%s' for the '%s' option

What it means

When parsing a compaction options map, CompactionParams.fromMap requires a 'class' sub-option naming the compaction strategy. If it is absent, a ConfigurationException is thrown, since Cassandra cannot determine which ICompactionStrategy to instantiate.

Solutions

1. Add the strategy class, e.g. compaction = {'class': 'SizeTieredCompactionStrategy', 'min_threshold': '4'}
2. Ensure tooling preserves the 'class' key when transforming option maps
3. Use fully qualified class names (org.apache.cassandra.db.compaction.*) for custom strategies

Example fix

// before
compaction = {'min_threshold': '4'}
// after
compaction = {'class': 'SizeTieredCompactionStrategy', 'min_threshold': '4'}

if (!compactionMap.containsKey("class"))
    throw new IllegalArgumentException("compaction map requires a 'class' sub-option");

boolean hasCompactionClass(Map<String,String> m) { return m != null && m.containsKey("class") && !m.get("class").trim().isEmpty(); }

try { compactionParams = CompactionParams.fromMap(map); } catch (ConfigurationException e) { if (e.getMessage().contains("Missing sub-option")) { /* add class key */ } throw e; }

When it happens

Trigger: ALTER TABLE ... WITH compaction = {'min_threshold': '4'} (no 'class' key); programmatic fromMap calls on maps that only carry tuning options.

Common situations: Hand-written DDL omitting the class; tooling that merges option maps and drops the class key; users confusing compression and compaction option shapes.

Understand the failure class

Background: "Must pass :limit option" / "Missing required option" — required option errors explained — this error's family across 41 libraries.

Related errors

• Invalid value for ' ' compaction sub-option - must be an…
• ACCESS TO DATACENTERS operations not supported by…
• ALREADY_EXISTS
• Already exists
• Because of this name

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/d9b55cebf1361b16. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/schema/CompactionParams.java:301

    public boolean onlyPurgeRepairedTombstones()
    {
        return onlyPurgeRepairedTombstones;
    }

    public boolean isEnabled()
    {
        return isEnabled;
    }

    public static CompactionParams fromMap(Map<String, String> map)
    {
        Map<String, String> options = new HashMap<>(map);

        String className = options.remove(Option.CLASS.toString());
        if (className == null)
        {
            throw new ConfigurationException(format("Missing sub-option '%s' for the '%s' option",
                                                    Option.CLASS,
                                                    TableParams.Option.COMPACTION));
        }

        return create(classFromName(className), options);
    }

    public static Class<? extends AbstractCompactionStrategy> classFromName(String name)
    {
        String className = name.contains(".")
                         ? name
                         : "org.apache.cassandra.db.compaction." + name;
        return FBUtilities.classForNameWithoutInitialization(className, "compaction strategy", AbstractCompactionStrategy.class);
    }

    /*
     * LCS doesn't, STCS and DTCS do
     */

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