Array element OID %v not registered while loading pgtype %q

Error message

Array element OID %v not registered while loading pgtype %q

What it means

Error "Array element OID %v not registered while loading pgtype %q" thrown in jackc/pgx.

Source

Thrown at derived_types.go:196

	sql := buildLoadDerivedTypesSQL(serverVersion, typeNames)
	rows, err := c.Query(ctx, sql, QueryResultFormats{TextFormatCode}, typeNames)
	if err != nil {
		return nil, fmt.Errorf("While generating load types query: %w", err)
	}
	defer rows.Close()
	result := make([]*pgtype.Type, 0, 100)
	for rows.Next() {
		ti := derivedTypeInfo{}
		err = rows.Scan(&ti.TypeName, &ti.NspName, &ti.Typtype, &ti.Typbasetype, &ti.Typelem, &ti.Oid, &ti.Rngtypid, &ti.Rngsubtype, &ti.Attnames, &ti.Atttypids)
		if err != nil {
			return nil, fmt.Errorf("While scanning type information: %w", err)
		}
		var type_ *pgtype.Type
		switch ti.Typtype {
		case "b": // array
			dt, ok := m.TypeForOID(ti.Typelem)
			if !ok {
				return nil, fmt.Errorf("Array element OID %v not registered while loading pgtype %q", ti.Typelem, ti.TypeName)
			}
			type_ = &pgtype.Type{Name: ti.TypeName, OID: ti.Oid, Codec: &pgtype.ArrayCodec{ElementType: dt}}
		case "c": // composite
			var fields []pgtype.CompositeCodecField
			for i, fieldName := range ti.Attnames {
				dt, ok := m.TypeForOID(ti.Atttypids[i])
				if !ok {
					return nil, fmt.Errorf("Unknown field for composite type %q:  field %q (OID %v) is not already registered.", ti.TypeName, fieldName, ti.Atttypids[i])
				}
				fields = append(fields, pgtype.CompositeCodecField{Name: fieldName, Type: dt})
			}

			type_ = &pgtype.Type{Name: ti.TypeName, OID: ti.Oid, Codec: &pgtype.CompositeCodec{Fields: fields}}
		case "d": // domain
			dt, ok := m.TypeForOID(ti.Typbasetype)
			if !ok {
				return nil, fmt.Errorf("Domain base type OID %v was not already registered, needed for %q", ti.Typbasetype, ti.TypeName)
			}

View on GitHub (pinned to ec1a0befd2)

When it happens

Trigger: Thrown at derived_types.go:196 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of jackc/pgx@ec1a0befd2 (2026-08-04). Data as JSON: /data/errors/1346a14946bfa543.json. Report an issue: GitHub.