apache/beam · critical

no database provided!

Error message

no database provided!

What it means

Panic raised at pipeline-construction time by spannerio.Write when the db argument is an empty string. The Spanner write transform needs a 'projects/.../instances/.../databases/...' database name to target; an empty one is almost always a missing/blank configuration value, and failing fast at graph construction prevents a broken pipeline from being submitted.

Solutions

1. Pass a non-empty database path projects/<proj>/instances/<inst>/databases/<db> to Write.
2. Validate the db string before constructing the pipeline.
3. Wire the database name through pipeline options so it is required at startup.

Example fix

// before
spannerio.Write(s, db, "users", col)
// after
if db == "" {
    panic("set --spanner_db flag")
}
spannerio.Write(s, db, "users", col)

if strings.TrimSpace(db) == "" {
    return fmt.Errorf("spanner database path is required for Write")
}

defer func() {
    if r := recover(); r != nil {
        err = fmt.Errorf("spannerio.Write: %v", r)
    }
}()

When it happens

Trigger: Calling spannerio.Write(s, "", table, col) or passing an uninitialized db variable.

Common situations: Missing Spanner database config, env vars not loaded, or pipelines parameterized from flags with no value set.

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

• database not provided!
• no database provided
• no database provided!
• spannerio.Query: invalid option
• unable to create batch read only transaction:

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/3d66eafe3efa3444. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/io/spannerio/write.go:51

type WriteOptionsFn func(qo *writeOptions) error

type writeOptions struct {
	BatchSize int
}

// UseBatchSize explicitly sets the batch size per transaction for writes.
func UseBatchSize(batchSize int) WriteOptionsFn {
	return func(qo *writeOptions) error {
		qo.BatchSize = batchSize
		return nil
	}
}

// Write writes the elements of the given PCollection<T> to spanner. T is required
// to be the schema type.
func Write(s beam.Scope, db string, table string, col beam.PCollection, options ...WriteOptionsFn) {
	if db == "" {
		panic("no database provided!")
	}

	if typex.IsCoGBK(col.Type()) || typex.IsKV(col.Type()) {
		panic("unsupported collection type - only normal structs supported for writing.")
	}

	s = s.Scope("spanner.Write")

	beam.ParDo0(s, newWriteFn(db, table, col.Type().Type(), options...), col)
}

type writeFn struct {
	spannerFn
	Table     string           `json:"table"`   // The table to write to
	Type      beam.EncodedType `json:"type"`    // Type is the encoded schema type.
	Options   writeOptions     `json:"options"` // Spanner write options
	mutations []*spanner.Mutation
}

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