datum_sum_int32 ensure_same_timetype_skiplist period_tagg period_tagg_transfn periodset_tagg_transfn time_tagg_combinefn timestamp_tagg tstzset_tagg_transfn

timestamp_tagg() TimestampTz * timestamp_tagg ( TimestampTz *  times1, int  count1, TimestampTz *  times2, int  count2, int *  newcount  )