+1 for this proposal Slightly related, but we can move this to a separate thread if it needs independent discussion: We should clarify the relationship between `row-id` and `first-row-id`. This has come up several times in our discussions about the equality delete removal proposal, where we considered generating `row-ids` manually instead of relying on the auto-assignment feature.
As discussed with Steven: > It is valid to add a new data file with a row: > > - whose persisted row-id value is lower than the snapshot's > first-row-id > - whose last-updated-seq-number is not set and inherit from the > snapshot sequence number > > Prashant Singh <[email protected]> ezt írta (időpont: 2025. nov. 22., Szo, 5:29): > +1 for making it explicit that an *undelete *of a row can't be done by > unsetting the corresponding bit in DV > > *Rows should only be added via new data files*, sounds reasonable to me ! > > apart from row-lineage it also complicates the operation type inference > like here [1] as we would now > inspect the contents of these DV to see if it's an insert ? > > [1] https://github.com/apache/iceberg/pull/14581#discussion_r2533057189 > > On Sat, Nov 22, 2025 at 4:48 AM Szehon Ho <[email protected]> wrote: > >> It makes sense to me, it sounds like a minor clarification. For v2 >> position deletes, code like rewrite_position_deletes may have made some >> assumptions like this and would not work well if violated, maybe other code >> as well. >> >> Thanks >> Szehon >> >> On Fri, Nov 21, 2025 at 3:03 PM Steven Wu <[email protected]> wrote: >> >>> Similar weird behavior can also happen for V2 position delete files with >>> `undelete`. >>> >>> In V2, there could be multiple position delete files (say pd1, pd2) >>> associated with the same data file (say f1). Let's say pd1 deletes row 5 >>> and 10 and pd2 deletes row 15. >>> 1. a new snapshot is committed with pd1 (DELETED), pd2 (EXISTING), and >>> pd3 (ADDED). pd3 deletes only row 10 (undeleted row 5) >>> 2. a new snapshot is committed with pd1 (DELETED) and pd2 (EXISTING) >>> >>> In either case, essentially some rows are added (back) to the table with >>> lower sequence number than the new snapshot's sequence number. >>> >>> >>> >>> Just to recap the question: should the spec (v2 and v3) spell out that >>> `undelete row` is not allowed? Rows should only be added via new data files. >>> >>> >>> >>> >>> On Fri, Nov 21, 2025 at 1:09 PM Steven Wu <[email protected]> wrote: >>> >>>> >Are we specifically stating somewhere that all row-ids should be >>>> higher than or equal to the snapshot's `first-row-id`? >>>> In my mental model the `first-row-id` is only applicable for rows that >>>> don't have a specific row-id assigned. >>>> >>>> I meant an ADDED row should have `row-id` higher than or equal to the >>>> snapshot's `first-row-id`. EXISTING or UPDATED row can have lower row id. >>>> >>>> On Fri, Nov 21, 2025 at 1:04 PM Steven Wu <[email protected]> wrote: >>>> >>>>> > Can we create a validator to prevent this from happening? >>>>> >>>>> We don't have this problem with the Java implementation. >>>>> `BaseDVFileWriter` merges the previous DV with the new delta DV. So there >>>>> is no `undelete` behavior. I am not aware of any Java API to allow >>>>> "undelete". So we probably don't need to add any validation code in the >>>>> Java impl. >>>>> >>>>> Just thought it is good to spell it out in the spec so that >>>>> clients/engines can be clear about the expected behavior. >>>>> >>>>> On Fri, Nov 21, 2025 at 12:18 PM Péter Váry < >>>>> [email protected]> wrote: >>>>> >>>>>> Are we specifically stating somewhere that all row-ids should be >>>>>> higher than or equal to the snapshot's `first-row-id`? >>>>>> In my mental model the `first-row-id` is only applicable for rows >>>>>> that don't have a specific row-id assigned. >>>>>> >>>>>> Noneless, I agree that the `row-id` and the >>>>>> `last-updated-seq-num` should have changed to a new one, so we can say >>>>>> that >>>>>> undeleting a row is not allowed because of this. >>>>>> >>>>>> Can we create a validator to prevent this from happening? >>>>>> >>>>>> >>>>>> >>>>>> Steven Wu <[email protected]> ezt írta (időpont: 2025. nov. 21., >>>>>> P, 21:11): >>>>>> >>>>>>> The undeleted row would have invalid `row-id` and >>>>>>> `last-updated-seq-num`. Since it is a new row (added back), it should >>>>>>> have >>>>>>> the `row-id` higher than or equal to the snapshot's `first-row-id` and >>>>>>> the >>>>>>> `last-updated-seq-number` should inherit/have the new snapshot's >>>>>>> sequence >>>>>>> number. >>>>>>> >>>>>>> On Fri, Nov 21, 2025 at 11:48 AM Steven Wu <[email protected]> >>>>>>> wrote: >>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> Should we clarify the V3 spec to explicitly formid "*undelete*" of >>>>>>>> a row by unsetting the DV bit? Unsetting a DV bit essentially adds a >>>>>>>> row >>>>>>>> with lower row-id than the snapshot's first-row-id, which would >>>>>>>> violate the >>>>>>>> row lineage spec. With the restriction, DV cardinality should be >>>>>>>> monotonically increasing. >>>>>>>> >>>>>>>> Thanks, >>>>>>>> Steven >>>>>>>> >>>>>>>
