jackc/pgx · error

Array element OID not registered while loading pgtype

Error message

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

What it means

LoadTypes encountered an array type ('b') whose element type OID is not already registered in the connection's TypeMap. Array registration requires its element type to be known first; the dependency was not included in the load set.

Solutions

1. Include the element type's name in the same LoadTypes call — the generated query loads transitive dependencies
2. Pre-register the element type before loading the array
3. Check that the element type is not from an uninstalled extension

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: /api/errors/1346a14946bfa543. Report an issue: GitHub.

Appendix: 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)
			}

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