apache/cassandra · error · ConfigurationException

is not a parsable float for

Error message

%s is not a parsable float for %s

What it means

ConfigurationException raised by SizeTieredCompactionStrategyOptions.parseDouble when a compaction option value (bucket_low or bucket_high) cannot be parsed as a double. It wraps the original NumberFormatException and names both the offending value and the option key so the invalid table option can be corrected. Thrown while validating strategy options at table creation/ALTER time.

Solutions

1. Correct the option value to use a decimal point, e.g. bucket_low = '0.5', bucket_high = '1.5'.
2. Remove the invalid option to fall back to the defaults (0.5 / 1.5).
3. Fix the emitting script/tool to always serialize doubles with '.' and no locale-specific formatting.

Example fix

// before
ALTER TABLE ks.t WITH compaction = {'class':'SizeTieredCompactionStrategy','bucket_low':'0,5'};
// after
ALTER TABLE ks.t WITH compaction = {'class':'SizeTieredCompactionStrategy','bucket_low':'0.5'};

function isValidDouble(v) { return v == null || !isNaN(Number(v.replace(',', '.'))) && Number(v.replace(',', '.')) > 0; }
if (!isValidDouble(opts.bucket_low) || !isValidDouble(opts.bucket_high)) throw new Error('bucket_low/bucket_high must be decimal numbers');

try { schema.alterTable(cql); } catch (ConfigurationException e) { if (e.getMessage().contains("not a parsable float")) { /* correct the option value and retry */ } else throw e; }

When it happens

Trigger: CREATE/ALTER TABLE with compaction option 'bucket_low' or 'bucket_high' set to a non-numeric string, e.g. {'class': 'SizeTieredCompactionStrategy', 'bucket_low': '0,5'} (comma decimal separator) or 'bucket_high': 'high'.

Common situations: Locale mistakes using ',' as decimal separator instead of '.'; typo or quoted-value mangling in cqlsh; automated config generators emitting empty strings for unset options.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• is not a parsable int (base10) for
• At most bytes may be in a compaction level; your…
• Cannot set concurrent_validations greater than…
• compaction_throughput: is too large; it should be less than…
• concurrent_compactors should be strictly greater than 0…

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/3b4a472f5c85cec9. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategyOptions.java:63

    }

    public SizeTieredCompactionStrategyOptions()
    {
        minSSTableSize = DEFAULT_MIN_SSTABLE_SIZE;
        bucketLow = DEFAULT_BUCKET_LOW;
        bucketHigh = DEFAULT_BUCKET_HIGH;
    }

    private static double parseDouble(Map<String, String> options, String key, double defaultValue) throws ConfigurationException
    {
        String optionValue = options.get(key);
        try
        {
            return optionValue == null ? defaultValue : Double.parseDouble(optionValue);
        }
        catch (NumberFormatException e)
        {
            throw new ConfigurationException(String.format("%s is not a parsable float for %s", optionValue, key), e);
        }
    }

    public static Map<String, String> validateOptions(Map<String, String> options, Map<String, String> uncheckedOptions) throws ConfigurationException
    {
        String optionValue = options.get(MIN_SSTABLE_SIZE_KEY);
        try
        {
            long minSSTableSize = optionValue == null ? DEFAULT_MIN_SSTABLE_SIZE : Long.parseLong(optionValue);
            if (minSSTableSize < 0)
            {
                throw new ConfigurationException(String.format("%s must be non negative: %d", MIN_SSTABLE_SIZE_KEY, minSSTableSize));
            }
        }
        catch (NumberFormatException e)
        {
            throw new ConfigurationException(String.format("%s is not a parsable int (base10) for %s", optionValue, MIN_SSTABLE_SIZE_KEY), e);
        }

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