benbjohnson/litestream · error

prepare statement: %w

Error message

prepare statement: %w

What it means

populateTable wraps a failed tx.Prepare of the batch INSERT statement in this error. The statement inserts data, text_field, int_field, float_field and timestamp for each row in the batch. On failure the transaction is rolled back first, then this error is returned, so no partial batch rows remain.

Source

Thrown at cmd/litestream-test/populate.go:186

	return nil
}

func (c *PopulateCommand) populateTable(ctx context.Context, db *sql.DB, tableName string, rowCount int) error {
	data := make([]byte, c.RowSize)

	for i := 0; i < rowCount; i += c.BatchSize {
		tx, err := db.Begin()
		if err != nil {
			return fmt.Errorf("begin transaction: %w", err)
		}

		stmt, err := tx.Prepare(fmt.Sprintf(`
			INSERT INTO %s (data, text_field, int_field, float_field, timestamp)
			VALUES (?, ?, ?, ?, ?)
		`, tableName))
		if err != nil {
			tx.Rollback()
			return fmt.Errorf("prepare statement: %w", err)
		}

		batchEnd := i + c.BatchSize
		if batchEnd > rowCount {
			batchEnd = rowCount
		}

		for j := i; j < batchEnd; j++ {
			cryptorand.Read(data)
			textField := fmt.Sprintf("row_%d_%d", i, j)
			intField := rand.Int63()
			floatField := rand.Float64() * 1000
			timestamp := time.Now().Unix()

			if _, err := stmt.Exec(data, textField, intField, floatField, timestamp); err != nil {
				stmt.Close()
				tx.Rollback()
				return fmt.Errorf("insert row: %w", err)

View on GitHub (pinned to 4ed7a308f6)

Solutions

1. Confirm the table was created with the expected columns (data, text_field, int_field, float_field, timestamp).
2. Check the table name is a plain identifier (test_table_N); re-create the database if it was made by an older version.
3. Read the wrapped SQLite error for 'no such table'/'no such column' hints.
4. Roll back as the code already does, then retry from a clean database if schema is suspect.

Example fix

// before
stmt, err := tx.Prepare(fmt.Sprintf("INSERT INTO %s (...) VALUES (...)", tableName))
// after
if err != nil {
    tx.Rollback()
    return fmt.Errorf("prepare statement for %s: %w", tableName, err) // surface table name for diagnosis
}

// verify table/columns exist before preparing the insert
rows, err := db.Query(fmt.Sprintf("PRAGMA table_info(%s)", tableName))
if err != nil {
    return err
}
defer rows.Close()
required := map[string]bool{"data": false, "text_field": false, "int_field": false, "float_field": false, "timestamp": false}
for rows.Next() {
    var cid int; var name, typ string; var notNull, pk int
    if err := rows.Scan(&cid, &name, &typ, &notNull, &pk); err == nil {
        if _, ok := required[name]; ok { required[name] = true }
    }
}
for col, ok := range required {
    if !ok { return fmt.Errorf("table %s missing column %s", tableName, col) }
}

stmt, err := tx.Prepare(insertSQL)
if err != nil {
    tx.Rollback()
    return fmt.Errorf("prepare statement: %w", err)
}

When it happens

Trigger: tx.Prepare(...) fails: SQL syntax error from a malformed table name interpolated into the statement, the table or its columns do not exist (schema drift), or the driver cannot allocate a statement handle.

Common situations: Re-running against a database whose tables were created by a different schema version; a table name containing characters that break the interpolated SQL; driver/connection state corrupted after a previous error.

Understand the failure class

Background: Database query failed: Internal Server Error 500s wrapping SQL, Prisma, and connection failures — what to check first — this error's family across 16 libraries.

Related errors

• open database: %w
• open database: %w
• set journal mode: %w
• create table %s: %w
• populate table %s: %w

AI-assisted analysis of benbjohnson/litestream@4ed7a308f6 (2026-09-06). Data as JSON: /api/errors/303df879c9469fc9. Report an issue: GitHub.