cayleygraph/cayley · error

error executing value lookup: %w

Error message

error executing value lookup: %w

What it means

NameOf performs a SELECT against the values table scanning string/bool/int/float/time columns to reconstruct the quad.Value. If the query fails for a reason other than ErrNoRows, it is wrapped as this error, so the underlying SQL error (connection loss, bad schema, locked table) is the cause.

Source

Thrown at graph/sql/quadstore.go:693

	} else {
		vtimeScan = &vtimeStd
		vtimeTime = &vtimeStd.Time
		vtimeValid = &vtimeStd.Valid
	}
	if err := c.Scan(
		&data,
		&str,
		&typ,
		&lang,
		&iri,
		&bnode,
		&vint,
		&vbool,
		&vfloat,
		vtimeScan,
	); err != nil {
		if err != sql.ErrNoRows {
			return nil, fmt.Errorf("error executing value lookup: %w", err)
		}
	}
	var val quad.Value
	if str.Valid {
		if iri.Bool {
			val = quad.IRI(str.String)
		} else if bnode.Bool {
			val = quad.BNode(str.String)
		} else if lang.Valid {
			val = quad.LangString{
				Value: quad.String(unescapeNullByte(str.String)),
				Lang:  lang.String,
			}
		} else if typ.Valid {
			val = quad.TypedString{
				Value: quad.String(unescapeNullByte(str.String)),
				Type:  quad.IRI(typ.String),
			}

View on GitHub (pinned to 81dcd7d73e)

Solutions

1. Check the wrapped cause with errors.Unwrap / %w to see the driver error
2. Verify the database schema matches the version expected by this quadstore (run migrations)
3. Test DB connectivity and credentials
4. Re-create or repair the values table if it is missing or corrupt

Example fix

// before
val, err := qs.NameOf(h) // opaque failure
// after
val, err := qs.NameOf(h)
if err != nil { log.Printf("cause: %v", errors.Unwrap(err)) }

val, err := qs.NameOf(h)
var cause error
for e := err; e != nil; e = errors.Unwrap(e) { cause = e }
if err != nil && cause != sql.ErrNoRows {
    // log cause; check DB connectivity/schema before retrying
}

When it happens

Trigger: Querying the values table when the DB connection is broken, the table doesn't exist or schema was migrated manually, or a driver-level error occurs during Scan.

Common situations: Schema version mismatch after upgrading Cayley without running migration; dropped/renamed values table; transient network errors between app and database.

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

• sql query failed: %v query: %v
• unsupported sql database: %q
• unsupported time format: %T: %v
• unmarshal value: %w
• ErrNoBucket

AI-assisted analysis of cayleygraph/cayley@81dcd7d73e (2026-09-06). Data as JSON: /api/errors/ca3fa546e23a42c1. Report an issue: GitHub.