> No. They were introduced at the same time. Great! Since the `summary` field and the `operation` key were introduced together, we should enforce the rule that the `summary` field must always have an accompanying `operation` key. This has been addressed in PR 11354 [1].
> I am strongly against this. The REST spec should be independent of the table versions. That makes sense. For the REST spec to support both V1 and V2 tables, it should "accept" the least common denominator between the two versions. For example, the `Snapshot` `summary` field is optional in V1 but required in V2. Therefore, the REST spec definition should mark the `summary` field as optional to support both versions. However, the current REST spec leans towards the V2 table spec; fields that are optional in V1 and required in V2 are marked as required in the spec, such as `TableMetadata.table-uuid` [2][3] and `Snapshot.summary` [4][5]. Would love to get other people's thoughts on this. Best, Kevin Liu [1] https://github.com/apache/iceberg/pull/11354 [2] https://github.com/apache/iceberg/blob/8e743a5b5209569f84b6bace36e1106c67e1eab3/open-api/rest-catalog-open-api.yaml#L2414 [3] https://iceberg.apache.org/spec/#table-metadata-fields [4] https://github.com/apache/iceberg/blob/8e743a5b5209569f84b6bace36e1106c67e1eab3/open-api/rest-catalog-open-api.yaml#L2325 [5] https://iceberg.apache.org/spec/#snapshots On Sun, Oct 20, 2024 at 11:24 AM rdb...@gmail.com <rdb...@gmail.com> wrote: > Was it ever valid to have a summary field without the operation key? > > No. They were introduced at the same time. > > Would it be helpful to create alternative versions of the REST spec > specifically for referencing V1 and V2 tables? > > I am strongly against this. The REST spec should be independent of the > table versions. Any table format version can be passed and the table format > should be the canonical reference for what is allowed. We want to avoid > cases where there are discrepancies. The table spec is canonical for table > metadata, and the REST spec allows passing it. > > On Sun, Oct 20, 2024 at 11:18 AM Kevin Liu <kevin.jq....@gmail.com> wrote: > >> Hey folks, >> >> Thanks, everyone for the discussion, and thanks Ryan for providing the >> historical context. >> Enforce the `operation` key in Snapshot’s `summary` field >> >> When serializing the `Snapshot` object from JSON, the Java implementation >> does not enforce that the `summary` field must contain an `operation` key. >> In the V1 spec, the `summary` field is optional, while in the V2 spec, it >> is required. However, in both versions, if a `summary` field is present, it >> must include an `operation` key. Any `summary` field lacking an `operation` >> key should be considered invalid. >> >> I’ve addressed this issue in PR 11354 [1] by adding this constraint when >> parsing JSON. >> >> > We initially did not have the snapshot summary or operation. When I >> added the summary, the operation was intended to be required in cases where >> the summary is present. It should always be there if the summary is and the >> summary should always be there unless you wrote the metadata.json file >> way back in 2017 or 2018. >> >> @Ryan, does this constraint also apply to `metadata.json` files from >> 2017/2018? Was it ever valid to have a `summary` field without the >> `operation` key? >> >> > Well, the spec says nothing about a top-level `operation` field in JSON >> [1]. Yet the Java implementation produces it [2] and removes the operation >> from the summary map. This seems inconsistent? >> >> @Anton, the Java `Snapshot` object includes both the `summary` and >> `operation` fields. When serializing to JSON, the `operation` field is >> included in the `summary` map [2], rather than as a top-level field. During >> deserialization from JSON, the `operation` field is extracted from the >> `summary` map [3]. >> >> I believe this is consistent with the table spec, which defines the JSON >> output, not how the `Snapshot` object is implemented in Java. >> On REST spec and Table spec >> >> Thanks, Yufei, for highlighting the difference between the REST spec and >> the table spec. I mistakenly used the REST spec >> (`rest-catalog-open-api.yaml` [4]) as the source of truth for V2 tables. >> >> Looking at the REST spec file, it can be challenging to determine how a >> REST server should handle V1 versus V2 tables. Even for V2 tables, the >> current version of the file combines features from V2, along with >> additional changes made in preparation for the upcoming V3 spec. >> >> Would it be helpful to create alternative versions of the REST spec >> specifically for referencing V1 and V2 tables? The goal would be to have a >> "frozen" version of the REST spec dedicated to V1 tables and another for V2 >> tables while allowing the current REST spec file to evolve as needed. >> >> Taking a step back, I think we need more documentation on the REST spec, >> including support for different table versions and guidance on upgrading >> from one version to another. I’d love to hear everyone’s thoughts on this. >> >> >> Best, >> >> Kevin Liu >> >> >> [1] https://github.com/apache/iceberg/pull/11354 >> >> [2] >> https://github.com/apache/iceberg/blob/17f1c4d2205b59c2bd877d4d31bbbef9e90979c5/core/src/main/java/org/apache/iceberg/SnapshotParser.java#L63-L66 >> >> [3] >> https://github.com/apache/iceberg/blob/17f1c4d2205b59c2bd877d4d31bbbef9e90979c5/core/src/main/java/org/apache/iceberg/SnapshotParser.java#L124-L137 >> >> [4] >> https://github.com/apache/iceberg/blob/main/open-api/rest-catalog-open-api.yaml >> >> >> On Sat, Oct 19, 2024 at 7:48 PM Sung Yun <sun...@apache.org> wrote: >> >>> Hi Ryan, thank you for your response! >>> >>> That detailed context is very helpful in allowing me to understanding >>> why the REST catalog spec has evolved the way it has, and how the Table >>> Spec and the REST Catalog Spec should each be referenced in the >>> sub-communities (like in PyIceberg). I'll keep those motivations in mind as >>> we discuss those Specs in the future. >>> >>> Also, here's a small PR to specify more explicitly that the operation >>> field should be a required field in the summary field: >>> https://github.com/apache/iceberg/pull/11355 >>> >>> Sung >>> >>> On 2024/10/19 22:14:59 "rdb...@gmail.com" wrote: >>> > I can provide some historical context here about how the table spec >>> evolved >>> > and how the REST spec works with respect to table versions. >>> > >>> > We initially did not have the snapshot summary or operation. When I >>> added >>> > the summary, the operation was intended to be required in cases where >>> the >>> > summary is present. It should always be there if the summary is and the >>> > summary should always be there unless you wrote the metadata.json file >>> way >>> > back in 2017 or 2018. It looks like the spec could be more clear that >>> the >>> > operation is required when summary is present. Anyone want to open a >>> PR? >>> > >>> > Anton, I don't think there is a top-level operation field. The Java >>> > Snapshot class tracks the operation as top-level, but it is always >>> stored >>> > in the summary. I think this is consistent with the spec. >>> > >>> > For the REST spec, I think that it should be strictly optional to >>> support >>> > v1 tables written with no summary, but it should always be present. I'd >>> > probably leave it required since it already is and is catching a >>> valuable >>> > error case here. >>> > >>> > When building the REST spec, I took the same approach as the Java >>> parser >>> > (which is also to parse table metadata coming from REST servers). That >>> is, >>> > it is compatible with v1 metadata; fields that were not required in v1 >>> are >>> > optional. This fits with the principle of "be liberal in what you >>> accept >>> > and strict in what you produce". The REST spec allows passing metadata >>> for >>> > any table version so that the specs are not tightly coupled. The table >>> > version is passed when loading and clients should reject table versions >>> > that are newer than what they can support. The REST protocol just >>> needs to >>> > facilitate passing the table metadata. >>> > >>> > Most v2 structures, like the `schemas` list, are introduced as >>> optional in >>> > v1 and made required in v2. That way, it's possible to add metadata to >>> > existing format versions and make the upgrade path easier. Maintaining >>> the >>> > newer structures even though there are different writer versions >>> deployed >>> > is one of the reasons why the REST spec changes to a change-based >>> model. >>> > New metadata only needs to be supported by the service maintaining the >>> > metadata.json files and any writers that want to update it. >>> > >>> > I see some points about being able to remove old table versions. I >>> don't >>> > think that the REST protocol itself is the place to do this. The >>> protocol >>> > is format-agnostic. Implementations are free to reject requests to >>> create >>> > tables with older versions, or to update the table to a new version. >>> > >>> > Ryan >>> > >>> > On Fri, Oct 18, 2024 at 6:42 AM Sung Yun <sun...@apache.org> wrote: >>> > >>> > > Folks, thank you for your responses! These area really helpful >>> insights. >>> > > >>> > > > I agree that the REST spec should aim to support v1, v2, and >>> potentially >>> > > the upcoming v3. In practice, it seems like the choice of table spec >>> might >>> > > ultimately be dictated by the REST catalog implementation. >>> > > >>> > > > A best practice would be for the server to strive to support all >>> Iceberg >>> > > versions, but the REST spec itself should remain flexible enough to >>> > > accommodate less strict table specs. >>> > > >>> > > Yufei, yes that makes sense, and I agree that the server should >>> strive to >>> > > support all format versions, because otherwise the an older client >>> > > application, may just not be compatible with a REST Catalog running >>> on a >>> > > higher version of table spec. I think we have two choices here in >>> ensuring >>> > > that the REST Catalog server is able to support multiple versions of >>> the >>> > > Table Spec: >>> > > >>> > > 1. We could create single components that are common denominators of >>> all >>> > > existing table specs to accommodate the less table specs. The REST >>> Catalog >>> > > Spec currently falls short in this approach, and I've put up this PR >>> to >>> > > show what this change would look like just for the Snapshot >>> component: >>> > > https://github.com/apache/iceberg/pull/11353 - My take on this is >>> that, >>> > > this approach will make the REST catalog spec more confusing and >>> difficult >>> > > to manage as we add more Table Spec versions moving forward. The >>> discussion >>> > > on this mail list thread is I think a great demonstration of that >>> confusion >>> > > :) >>> > > 2. We could instead create separate Table Spec version specific >>> components >>> > > on the REST Catalog Open API Spec. For example, a Snapshot component >>> could >>> > > be anyOf SnapshotV1 and SnapshotV2, which match the Table Spec V1 >>> and V2 >>> > > definitions. I think creating explicit components that match the spec >>> > > definitions will work in our favor when we continue to introduce >>> more Spec >>> > > changes and manage their lifecycles. And perhaps, maybe we could also >>> > > indicate what format-versions the REST Catalog Server supports >>> through an >>> > > endpoint, and communicate it to a client application. >>> > > >>> > > I'd love to hear the community's opinion on suggestion (2)! I'm very >>> > > curious to hear if we've considered it before. >>> > > >>> > > Sung >>> > > >>> > > On 2024/10/18 05:13:15 Péter Váry wrote: >>> > > > Hi Team, >>> > > > Apart from fixing this current issue by relaxing the current spec >>> > > > constraints, to support both v1 and v2 specifications, we should >>> think >>> > > > about how to handle table spec evolution for the long term. >>> > > > >>> > > > What are the base factors we can start from (please add your own >>> ideas >>> > > if I >>> > > > have missed something): >>> > > > - We evolve the specifications in a way that is backwards >>> compatible (v1 >>> > > > table could be read by v2 reader) but not forwards compatible (v2 >>> table >>> > > > could not be read by an old reader) >>> > > > - The rest spec ideally should conform to the currently used table >>> spec >>> > > > schema/constraints >>> > > > - REST catalogs sooner-or-later would like to drop support for >>> older >>> > > table >>> > > > spec. We need to avoid the situation of Hive Metastore, where the >>> > > decisions >>> > > > made 10 years ago prevented enhancing the APIs as the old >>> specifications >>> > > > were supported forever. >>> > > > >>> > > > Probably (when the spec difference becomes big enough) a composit >>> request >>> > > > (version + different content spec) or a different endpoint will be >>> > > required. >>> > > > >>> > > > Thanks, Peter >>> > > > >>> > > > On Thu, Oct 17, 2024, 23:11 Yufei Gu <flyrain...@gmail.com> wrote: >>> > > > >>> > > > > Hi Sung, >>> > > > > >>> > > > > It seems we are running to issues related to a mismatch between >>> the >>> > > REST >>> > > > > spec and table specifications. Currently, there's no clear >>> definition >>> > > of >>> > > > > how the REST spec is meant to support different table specs. The >>> > > closest >>> > > > > reference I found is this statement >>> > > > > < >>> > > >>> https://github.com/apache/iceberg/blob/8e743a5b5209569f84b6bace36e1106c67e1eab3/open-api/rest-catalog-open-api.yaml#L30-L30 >>> > > > >>> > > > > in the REST spec. >>> > > > > >>> > > > > Implementations should ideally support both Iceberg table specs >>> v1 and >>> > > v2, >>> > > > >> with priority given to v2. >>> > > > > >>> > > > > >>> > > > > I agree that the REST spec should aim to support v1, v2, and >>> > > potentially >>> > > > > the upcoming v3. In practice, it seems like the choice of table >>> spec >>> > > might >>> > > > > ultimately be dictated by the REST catalog implementation. >>> > > > > >>> > > > > >>> > > > > A best practice would be for the server to strive to support all >>> > > Iceberg >>> > > > > versions, but the REST spec itself should remain flexible enough >>> to >>> > > > > accommodate less strict table specs. For the case you mentioned, >>> it >>> > > should >>> > > > > be fine to make sequence number optional since the spec has to >>> support >>> > > v1 >>> > > > > table spec. It does feel confusing though. >>> > > > > >>> > > > > >>> > > > > WDYT? >>> > > > > >>> > > > > >>> > > > > Yufei >>> > > > > >>> > > > > >>> > > > > On Thu, Oct 17, 2024 at 1:56 PM Anton Okolnychyi < >>> > > aokolnyc...@gmail.com> >>> > > > > wrote: >>> > > > > >>> > > > >> Well, the spec says nothing about a top-level `operation` field >>> in >>> > > JSON >>> > > > >> [1]. Yet the Java implementation produces it [2] and removes the >>> > > operation >>> > > > >> from the summary map. This seems inconsistent? >>> > > > >> >>> > > > >> - Anton >>> > > > >> >>> > > > >> [1] - https://iceberg.apache.org/spec/#snapshots >>> > > > >> [2] - >>> > > > >> >>> > > >>> https://github.com/apache/iceberg/blob/17f1c4d2205b59c2bd877d4d31bbbef9e90979c5/core/src/main/java/org/apache/iceberg/SnapshotParser.java#L63 >>> > > > >> >>> > > > >> >>> > > > >> чт, 17 жовт. 2024 р. о 10:06 Sung Yun <sun...@apache.org> пише: >>> > > > >> >>> > > > >>> > As a side note, the `rest-catalog-open-api.yaml` file [2] in >>> the >>> > > > >>> Iceberg repo contains the latest version of the spec. >>> > > > >>> >>> > > > >>> I think more clarity on this would be helpful. Is it really >>> the case >>> > > > >>> that the Open API spec contains the latest version of the >>> spec? For >>> > > > >>> example, I'm noticing a discrepancy between sequence-number in >>> the >>> > > Table >>> > > > >>> Spec and in the Open API Spec... >>> > > > >>> >>> > > > >>> In the table spec, it's required for V2, but it's optional in >>> the >>> > > REST >>> > > > >>> API Spec: >>> > > > >>> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/main/open-api/rest-catalog-open-api.yaml#L2319-L2335 >>> > > > >>> >>> > > > >>> On 2024/10/17 16:58:17 Kevin Liu wrote: >>> > > > >>> > > Based on the example metadata, that looks like it is not to >>> > > spec, so >>> > > > >>> it's >>> > > > >>> > reasonable that python would reject it. If the java >>> > > implementation is >>> > > > >>> > allowing for that, it's likely that we're being too relaxed >>> > > (possibly a >>> > > > >>> > holdover from v1 parsing). >>> > > > >>> > I believe the Java implementation is relaxing the >>> constraint. I'll >>> > > > >>> create a >>> > > > >>> > PR with test cases and the necessary changes. >>> > > > >>> > >>> > > > >>> > > Do you know what produced the metadata? >>> > > > >>> > It was created by Snowflake [1]. After verifying this, I'll >>> look >>> > > into >>> > > > >>> > raising the issue with them. >>> > > > >>> > >>> > > > >>> > As a side note, the `rest-catalog-open-api.yaml` file [2] in >>> the >>> > > > >>> Iceberg >>> > > > >>> > repo contains the latest version of the spec. As we're >>> continuing >>> > > to >>> > > > >>> evolve >>> > > > >>> > to spec for V3, would it be helpful to create a frozen >>> version >>> > > > >>> representing >>> > > > >>> > both the V1 and V2 specs for reference, possibly as a >>> separate >>> > > file? >>> > > > >>> > >>> > > > >>> > Best, >>> > > > >>> > Kevin Liu >>> > > > >>> > >>> > > > >>> > [1] >>> > > > >>> > >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg-python/issues/1106#issuecomment-2312108455 >>> > > > >>> > [2] >>> > > > >>> > >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/8e2eb9ac2e33ce4bac8956d4e2f099444d03c0e3/open-api/rest-catalog-open-api.yaml >>> > > > >>> > >>> > > > >>> > On Thu, Oct 17, 2024 at 9:20 AM Daniel Weeks < >>> dwe...@apache.org> >>> > > > >>> wrote: >>> > > > >>> > >>> > > > >>> > > Sung, >>> > > > >>> > > >>> > > > >>> > > I was thinking of v1, so you're right that manifest-list >>> and >>> > > summary >>> > > > >>> are >>> > > > >>> > > required as of v2. The REST Spec seems to follow the v2 >>> > > definition, >>> > > > >>> so I >>> > > > >>> > > think we're somewhat implicitly requiring those fields via >>> REST. >>> > > > >>> > > >>> > > > >>> > > Kevin, >>> > > > >>> > > >>> > > > >>> > > Based on the example metadata, that looks like it is not to >>> > > spec, so >>> > > > >>> it's >>> > > > >>> > > reasonable that python would reject it. If the java >>> > > implementation >>> > > > >>> is >>> > > > >>> > > allowing for that, it's likely that we're being too relaxed >>> > > > >>> (possibly a >>> > > > >>> > > holdover from v1 parsing). >>> > > > >>> > > >>> > > > >>> > > Do you know what produced the metadata? >>> > > > >>> > > >>> > > > >>> > > -Dan >>> > > > >>> > > >>> > > > >>> > > On Thu, Oct 17, 2024 at 9:02 AM Kevin Liu < >>> > > kevin.jq....@gmail.com> >>> > > > >>> wrote: >>> > > > >>> > > >>> > > > >>> > >> Thanks for the additional context. >>> > > > >>> > >> >>> > > > >>> > >> My understanding is that if a Snapshot has a `summary` >>> field, it >>> > > > >>> must >>> > > > >>> > >> also have a corresponding `operation` key in the summary >>> map. Is >>> > > > >>> that >>> > > > >>> > >> correct? Based on the `SnapshotParser`, this is not >>> enforced >>> > > [1]. >>> > > > >>> > >> >>> > > > >>> > >> The underlying issue in #1106 [2] is the missing >>> `operation` >>> > > field >>> > > > >>> when >>> > > > >>> > >> the `summary` field is present. >>> > > > >>> > >> For example, >>> > > > >>> > >> ``` >>> > > > >>> > >> "summary" : { >>> > > > >>> > >> "manifests-created" : "8", >>> > > > >>> > >> "total-records" : "26508666891", >>> > > > >>> > >> "added-files-size" : "3927895626752", >>> > > > >>> > >> "manifests-kept" : "0", >>> > > > >>> > >> "total-files-size" : "3927895626752", >>> > > > >>> > >> "added-records" : "26508666891", >>> > > > >>> > >> "added-data-files" : "231513", >>> > > > >>> > >> "manifests-replaced" : "0", >>> > > > >>> > >> "total-data-files" : "231513" >>> > > > >>> > >> } >>> > > > >>> > >> ``` >>> > > > >>> > >> >>> > > > >>> > >> It could be the case that this particular `metadata.json` >>> was >>> > > > >>> generated >>> > > > >>> > >> not according to the spec. >>> > > > >>> > >> >>> > > > >>> > >> Best, >>> > > > >>> > >> Kevin Liu >>> > > > >>> > >> >>> > > > >>> > >> >>> > > > >>> > >> [1] >>> > > > >>> > >> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/17f1c4d2205b59c2bd877d4d31bbbef9e90979c5/core/src/main/java/org/apache/iceberg/SnapshotParser.java#L124-L142 >>> > > > >>> > >> [2] https://github.com/apache/iceberg-python/issues/1106 >>> > > > >>> > >> >>> > > > >>> > >> >>> > > > >>> > >> On Thu, Oct 17, 2024 at 8:47 AM Sung Yun < >>> sun...@apache.org> >>> > > wrote: >>> > > > >>> > >> >>> > > > >>> > >>> Thank you for the clarification Daniel, and thank you >>> Kevin for >>> > > > >>> raising >>> > > > >>> > >>> this issue! >>> > > > >>> > >>> >>> > > > >>> > >>> Does that mean that we are creating component schemas >>> that are >>> > > the >>> > > > >>> > >>> superset of the V1 and V2 schemas? And if so, should we >>> remove >>> > > > >>> summary and >>> > > > >>> > >>> manifest-list from the required properties, and add >>> manifests >>> > > > >>> optional >>> > > > >>> > >>> property to the Snapshot schema to support both V1 and V2 >>> > > Summary >>> > > > >>> specs? >>> > > > >>> > >>> https://iceberg.apache.org/spec/#snapshots >>> > > > >>> > >>> >>> > > > >>> > >>> Or would creating separate component schemas for V1/V2 >>> be a >>> > > > >>> cleaner way >>> > > > >>> > >>> to align the REST spec with the table spec? >>> > > > >>> > >>> >>> > > > >>> > >>> Sung >>> > > > >>> > >>> >>> > > > >>> > >>> On 2024/10/17 15:19:23 Daniel Weeks wrote: >>> > > > >>> > >>> > I'm not convinced this is incorrect behavior (table >>> spec or >>> > > > >>> > >>> > implementation), but it does lend to some confusion. >>> The >>> > > > >>> 'summary' >>> > > > >>> > >>> field >>> > > > >>> > >>> > is optional, which means that if a summary is not >>> provided, >>> > > you >>> > > > >>> do not >>> > > > >>> > >>> have >>> > > > >>> > >>> > an associated 'operation' field. The 'operation' >>> field is >>> > > only >>> > > > >>> > >>> required in >>> > > > >>> > >>> > the context of the summary, so it's actually possible >>> for the >>> > > > >>> > >>> > implementation (i.e. the tests you reference) to not >>> have an >>> > > > >>> operation. >>> > > > >>> > >>> > >>> > > > >>> > >>> > I think what is wrong here is that the REST spec >>> marked the >>> > > > >>> summary as >>> > > > >>> > >>> > required >>> > > > >>> > >>> > < >>> > > > >>> > >>> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/8e2eb9ac2e33ce4bac8956d4e2f099444d03c0e3/open-api/rest-catalog-open-api.yaml#L2040 >>> > > > >>> > >>> >, >>> > > > >>> > >>> > which is inconsistent with the table spec. >>> > > > >>> > >>> > >>> > > > >>> > >>> > On Wed, Oct 16, 2024 at 3:52 PM Anton Okolnychyi < >>> > > > >>> > >>> aokolnyc...@gmail.com> >>> > > > >>> > >>> > wrote: >>> > > > >>> > >>> > >>> > > > >>> > >>> > > Based on [1], we never persisted the operation in the >>> > > summary >>> > > > >>> map. >>> > > > >>> > >>> > > Instead, we persisted it as a top-level field in >>> Java, >>> > > which is >>> > > > >>> > >>> actually >>> > > > >>> > >>> > > NOT what the spec says. Does anyone remember cases >>> when the >>> > > > >>> > >>> operation was >>> > > > >>> > >>> > > unknown? I personally don't. >>> > > > >>> > >>> > > >>> > > > >>> > >>> > > [1] - >>> > > > >>> > >>> > > >>> > > > >>> > >>> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/17f1c4d2205b59c2bd877d4d31bbbef9e90979c5/core/src/main/java/org/apache/iceberg/SnapshotParser.java#L63 >>> > > > >>> > >>> > > >>> > > > >>> > >>> > > >>> > > > >>> > >>> > > ср, 16 жовт. 2024 р. о 12:42 Kevin Liu < >>> > > kevin.jq....@gmail.com >>> > > > >>> > >>> > > > >>> > >>> пише: >>> > > > >>> > >>> > > >>> > > > >>> > >>> > >> Hey folks, >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >> I’ve noticed a discrepancy between the Iceberg >>> > > specification >>> > > > >>> and >>> > > > >>> > >>> the Java >>> > > > >>> > >>> > >> implementation regarding the `operation` key in the >>> > > `Snapshot` >>> > > > >>> > >>> `summary` >>> > > > >>> > >>> > >> field. >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >> The `Snapshot` object's `summary` dictionary >>> includes a >>> > > > >>> *required* >>> > > > >>> > >>> key >>> > > > >>> > >>> > >> named `operation`, as outlined in the spec >>> describing >>> > > Table >>> > > > >>> > >>> Metadata and >>> > > > >>> > >>> > >> Snapshots [1] and the generated OpenAPI YAML [2]. >>> > > However, in >>> > > > >>> the >>> > > > >>> > >>> Java >>> > > > >>> > >>> > >> implementation [3], `operation` is treated as >>> optional. In >>> > > > >>> > >>> contrast, it >>> > > > >>> > >>> > >> remains a required field in the Python >>> implementation [4]. >>> > > > >>> > >>> > >> I also found that Java tests for `SnapshotParser` >>> assert >>> > > that >>> > > > >>> the >>> > > > >>> > >>> > >> `operation` field is null. [5] >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >> Due to this discrepancy, a user reported [6] that >>> the >>> > > > >>> > >>> `metadata.json` >>> > > > >>> > >>> > >> file generated for an Iceberg table could not be >>> read by >>> > > > >>> PyIceberg, >>> > > > >>> > >>> though >>> > > > >>> > >>> > >> it is readable using the Iceberg Java library. >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >> How should we proceed from here? Should the Java >>> library >>> > > > >>> enforce >>> > > > >>> > >>> this >>> > > > >>> > >>> > >> requirement? Additionally, how should we handle >>> existing >>> > > > >>> > >>> `metadata.json` >>> > > > >>> > >>> > >> files that were generated without this field? >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >> Best, >>> > > > >>> > >>> > >> Kevin Liu >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >> [1] >>> > > > >>> https://iceberg.apache.org/spec/#table-metadata-and-snapshots >>> > > > >>> > >>> > >> [2] >>> > > > >>> > >>> > >> >>> > > > >>> > >>> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/8e2eb9ac2e33ce4bac8956d4e2f099444d03c0e3/open-api/rest-catalog-open-api.yaml#L2057-L2060 >>> > > > >>> > >>> > >> [3] >>> > > > >>> > >>> > >> >>> > > > >>> > >>> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/64b36999d7ff716ae2534fb0972fcc10d22a64c2/core/src/main/java/org/apache/iceberg/SnapshotParser.java#L124 >>> > > > >>> > >>> > >> [4] >>> > > > >>> > >>> > >> >>> > > > >>> > >>> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg-python/blob/7cf0c225c3cdb32ac5e390de06b7b0e4fe7de92e/pyiceberg/table/snapshots.py#L182 >>> > > > >>> > >>> > >> [5] >>> > > > >>> > >>> > >> >>> > > > >>> > >>> >>> > > > >>> >>> > > >>> https://github.com/apache/iceberg/blob/22a6b19c2e226eacc0aa78c1f2ffbdbb168b13be/core/src/test/java/org/apache/iceberg/TestSnapshotJson.java#L52 >>> > > > >>> > >>> > >> [6] >>> https://github.com/apache/iceberg-python/issues/1106 >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >> >>> > > > >>> > >>> > >>> > > > >>> > >>> >>> > > > >>> > >> >>> > > > >>> > >>> > > > >>> >>> > > > >> >>> > > > >>> > > >>> > >>> >>
