class PostgresqlSerializer extends MysqlSerializer {

    public PostgresqlSerializer(HugeConfig config) {
        super(config);
    }

    @Override
    public BackendEntry writeIndex(HugeIndex index) {<FILL_FUNCTION_BODY>}
}

        TableBackendEntry entry = newBackendEntry(index);
        /*
         * When field-values is null and elementIds size is 0, it is
         * meaningful for deletion of index data in secondary/range index.
         */
        if (index.fieldValues() == null && index.elementIds().isEmpty()) {
            entry.column(HugeKeys.INDEX_LABEL_ID, index.indexLabel().longId());
        } else {
            Object value = index.fieldValues();
            if ("\u0000".equals(value)) {
                value = Strings.EMPTY;
            }
            entry.column(HugeKeys.FIELD_VALUES, value);
            entry.column(HugeKeys.INDEX_LABEL_ID, index.indexLabel().longId());
            entry.column(HugeKeys.ELEMENT_IDS,
                         IdUtil.writeStoredString(index.elementId()));
            entry.column(HugeKeys.EXPIRED_TIME, index.expiredTime());
            entry.subId(index.elementId());
        }
        return entry;
    
<methods>public void <init>(HugeConfig) ,public org.apache.hugegraph.backend.store.mysql.MysqlBackendEntry newBackendEntry(org.apache.hugegraph.type.HugeType, org.apache.hugegraph.backend.id.Id) ,public org.apache.hugegraph.backend.store.BackendEntry writeOlapVertex(org.apache.hugegraph.structure.HugeVertex) <variables>