What causes "Failed to retrieve target column for: " in apache/cassandra?

Verify the column name with DESCRIBE TABLE and correct the target

apache/cassandra · error · InvalidRequestException

Failed to retrieve target column for:

Error message

Failed to retrieve target column for:

What it means

After the target string passes shape checks, validateOptions calls TargetParser.parse; if it returns null (no matching column/type combination), SAI throws InvalidRequestException("Failed to retrieve target column for: " + targetColumn). This means the target string is syntactically plausible but does not resolve to an indexable column in the table metadata.

Solutions

Verify the column name with DESCRIBE TABLE and correct the target
Remove unsupported wrappers — use plain column name for scalars, keys/values/entries only for maps, full() only for frozen collections
Quote the identifier if the column has mixed case
Recreate the index after the column exists

Example fix

// before
CREATE CUSTOM INDEX idx ON ks.tbl (Email) USING 'StorageAttachedIndex'; // no such column
// after
CREATE CUSTOM INDEX idx ON ks.tbl (email) USING 'StorageAttachedIndex';

Defensive patterns

Strategy: validation

Validate before calling

if (metadata.getColumn(new ColumnIdentifier(targetColumn, true)) == null && TargetParser.tryParse(metadata, targetColumn) == null)
    throw new IllegalArgumentException("Target does not resolve to an indexable column: " + targetColumn);

Try / catch

try { session.execute(ddl); } catch (InvalidRequestException e) { if (e.getMessage().contains("Failed to retrieve target column")) { /* correct column name or wrapper */ } else throw e; }

Prevention

Confirm column names via DESCRIBE TABLE before creating indexes (watch identifier case)
Only use keys/values/entries on maps and full() on frozen collections
Run CREATE INDEX statements through a staging environment first

When it happens

Trigger: CREATE CUSTOM INDEX USING StorageAttachedIndex with a target naming a nonexistent column, an unsupported function wrapper (e.g. keys() on a non-map), or invalid syntax like full() on non-frozen types.

Common situations: Typos in column names; using keys()/values()/entries() on set/list columns or plain columns; target on a column dropped before index creation; case-sensitivity mistakes (unquoted "Email" vs email).

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/f447761b68ef6cbf. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/index/sai/StorageAttachedIndex.java:262

        }

        String targetColumn = options.get(IndexTarget.TARGET_OPTION_NAME);

        if (targetColumn == null)
        {
            throw new InvalidRequestException("Missing target column");
        }

        if (targetColumn.split(",").length > 1)
        {
            throw new InvalidRequestException("A storage-attached index cannot be created over multiple columns: " + targetColumn);
        }

        Pair<ColumnMetadata, IndexTarget.Type> target = TargetParser.parse(metadata, targetColumn);

        if (target == null)
        {
            throw new InvalidRequestException("Failed to retrieve target column for: " + targetColumn);
        }

        // In order to support different index targets on non-frozen map, ie. KEYS, VALUE, ENTRIES, we need to put index
        // name as part of index file name instead of column name. We only need to check that the target is different
        // between indexes. This will only allow indexes in the same column with a different IndexTarget.Type.
        //
        // Note that: "metadata.indexes" already includes current index
        if (metadata.indexes.stream().filter(index -> index.getIndexClassName().equals(StorageAttachedIndex.class.getName()))
                            .map(index -> TargetParser.parse(metadata, index.options.get(IndexTarget.TARGET_OPTION_NAME)))
                            .filter(Objects::nonNull).filter(t -> t.equals(target)).count() > 1)
        {
            throw new InvalidRequestException("Cannot create more than one storage-attached index on the same column: " + target.left);
        }

        Map<String, String> analysisOptions = AbstractAnalyzer.getAnalyzerOptions(options);
        if (target.left.isPrimaryKeyColumn() && !analysisOptions.isEmpty())
        {
            throw new InvalidRequestException(ANALYSIS_ON_KEY_COLUMNS_MESSAGE + new CqlBuilder().append(analysisOptions));

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