Yeah I think Iceberg and Hive are the only ones trying to make life difficult, that I think we should also cover but in changes to the Iceberg Spec. Hive can just stay how it is ...
On Mon, May 19, 2025 at 2:59 PM Dmitri Bourlatchkov <di...@apache.org> wrote: > For context: my locations concerns are rooted in Nessie's experience where > we often get problem reports related to files being outside the declared > Iceberg metadata location. > > Example: > > https://github.com/projectnessie/nessie/issues/10817#issuecomment-2887329227 > > I'm ok going with a single location for generic tables, but I think Polaris > needs to have a more strict spec for that (define where file should and > should not go) because polaris owns this spec. Polaris ought to define what > complies with the spec and what does not. Having a proper spec is essential > to ensure a mutual understanding of all parties dealing with Generic > Tables. > > Open API yaml comments are not sufficient, IMHO. I'd prefer to have a > dedicated doc page to define expectations and compliance. > > Thanks, > Dmitri. > > > On Mon, May 19, 2025 at 2:17 PM Russell Spitzer <russell.spit...@gmail.com > > > wrote: > > > The only multiple locations table formats I'm currently aware of are Hive > > (partitions can live wherever) and Iceberg. > > > > I think for Delta, Hudi, LanceDB, Paimon and File based tables they all > > have to live in the root location. I'm not sure of any other "file" based > > tables where this would be an issue but I'd love to know if someone else > > has ideas. I think with the rise in credential vending, splitting things > > amongst multiple prefixes is becoming less common. I don't oppose doing > an > > array of locations but it may be enough to just leave this as an > extension > > later. (Support location or locations) > > > > On Wed, May 7, 2025 at 8:52 PM yun zou <yunzou.colost...@gmail.com> > wrote: > > > > > Hi Dmitri, > > > > > > If it's not "all" is it not strong enough for a spec, IMHO. If some > > tables > > > have multiple base locations how is Polaris going to deal with them? > > > > > > Sorry, when I say most of them, it was because I haven't tested all of > > them > > > (I only tested Delta and CSV before). > > > However, if Unity Catalog is only taking one location, I think that is > a > > > strong enough proof that > > > one location is enough today. > > > > > > It is also more natural to start with one location, and if there are > use > > > cases that > > > require support for multiple locations later, we can move on to V2 spec > > to > > > support multiple > > > tables locations. > > > > > > We're making a specification for Polaris. I do not think it is > sufficient > > > to say we'll do the same as other (unspecified ATM) catalogs. > > > If we want to migrate users from other Catalog services to Polaris > > (through > > > federation), then Polaris will need to > > > provide corresponding capabilities. For example, Unity Catalog storage > > > location is a URI representation, when entity > > > are federated from Unity Catalog, we will need to be able to handle the > > URI > > > location. > > > If URI representation is a common standard that has been accepted by > > other > > > Catalog services like Unity Catalog, Gravitino, > > > Polaris should be compatible with that, otherwise it might cause > problem > > > for users when they are migrating from one to > > > another. > > > > > > What will Polaris Server do with this location? > > > For generic tables, Polaris will provide credential vending for this > > > location in near future, I don't see we will provide > > > anything else in short or mid term, since we still want to promote > > > native support for Iceberg. > > > Or if you have anything special in your mind that you think we should > > > support? > > > > > > If Polaris has to define it in a spec, it will be hard to change in the > > > future. > > > Regardless of whether it is explicitly in the spec definition or as a > > > reserved property key, as long as they are explicitly > > > documented, they will be hard to change in the future. From that > > > perspective, those two approaches seem the same to me. > > > > > > Table location is critical information that is required by the engine > > side > > > to read and write the tables, which should > > > be explicitly defined to provide better sharing across engines. For > > > example, the delta table location is passed in the > > > table properties with a property key either "location" or "path" > depends > > on > > > how the table is created. Now, if another > > > engine wants to read the delta table, it will need to understand those > > > keys, which are controlled by Spark today. If Spark > > > changes them one day, all sharing will stop working. > > > > > > As to whether we want to put it as an explicit field or a reserved > key, I > > > think for a common field among various > > > table formats, it makes more sense to have it as an explicit field. For > > > properties that are specific to a particular table format, > > > it is more proper to just have a reserved key. > > > > > > If Polaris takes control of the location, I think we have to be more > > > careful > > > and at least try to make it future-proof. > > > > > > I don't think Polaris is taking control of the location, the location > is > > > still controlled by the engine and users today like table names. > > > Polaris is a Catalog service, it records the generic table entity, and > > > returns the information back to the user on query. > > > It might be able to do some validation on the location (like check > > special > > > character), but it doesn't decide which location > > > the table will be used. I personally don't think it is a bad idea to > let > > > the Catalog service also take control of generating > > > the table location, but I think that will require a lot of work. > > > > > > Best Regards, > > > Yun > > > > > > On Wed, May 7, 2025 at 5:22 PM Dmitri Bourlatchkov <di...@apache.org> > > > wrote: > > > > > > > No worries about the name. It is a possible alternative spelling :) > > > > > > > > On Wed, May 7, 2025 at 8:04 PM yun zou <yunzou.colost...@gmail.com> > > > wrote: > > > > > > > > > Hi Dmitri, > > > > > > > > > > Sorry, I accidentally typed your name wrong in the previous reply! > > > > > Apologize for this! > > > > > > > > > > For the S3 issue, I think we will need to deal with those > regardless, > > > > > especially with the federation work going on, we will need to > handle > > > all > > > > > those entities eventually coming from different Catalogs, and the > URI > > > > > format seems the standard format used by various Catalog services. > > > > > > > > > > Best Regards, > > > > > Yun > > > > > > > > > > On Wed, May 7, 2025 at 4:55 PM yun zou <yunzou.colost...@gmail.com > > > > > > wrote: > > > > > > > > > > > Hi Dimitri and Eric, > > > > > > > > > > > > Thanks a lot for the feedback! > > > > > > > > > > > > For the questions: > > > > > > - Is one value or many? > > > > > > It will be one value, similar to the location in Iceberg and the > > > > > > storage_location in unity catalog. > > > > > > > > > > > > Regarding to the point about having new data in new locations and > > > > keeping > > > > > > old data in old locations, do we support that for Iceberg > > > > > > today? > > > > > > For most of the Spark tables, it seems to only have one location. > > > > Also, I > > > > > > think it is better to start restricted first, and then extend it > to > > > > > > allow multiple locations when the use case raises. > > > > > > > > > > > > Ref: > > > > > > Iceberg location: > > > > > > > > > > > > > > > > > > > > > https://github.com/apache/iceberg/blob/main/open-api/rest-catalog-open-api.yaml#L3451 > > > > > > Storage location in Unity Catalog: > > > > > > > > > > > > > > > > > > > > > https://github.com/apache/iceberg/blob/main/open-api/rest-catalog-open-api.yaml#L3451 > > > > > > > > > > > > - Is it a URI? > > > > > > Yes, it will be a URI, which seems the standard catalog > > > implementation. > > > > > > Regarding to the point about s3 v2 s3a, i assume that is a common > > > > > > problem that every catalog implementation needs to address, and > we > > > will > > > > > > stay the same on this part. At least from the load table point of > > > view, > > > > > > Spark engine knows how to deal with such cases. > > > > > > > > > > > > - Does it point to any particular file? > > > > > > No, it doesn't point to a particular file. It is the base table > > > > location. > > > > > > > > > > > > - Is it a common prefix of all files within a table? > > > > > > It is supposed to be the base table location, which theoretically > > > > should > > > > > > be the common prefix of all files within a table I believe. > > > > > > > > > > > > - What happens when a value does not match these expectations? > > > > > > Whether it is one value or many is restricted by the spec > already. > > > > > > For URI format, I think we can do a format check, and fail it. > > > > > > Other than that, we will not do any other special check, and we > > rely > > > on > > > > > > the client to put the correct value, otherwise, the other engine > > will > > > > > > not be able to successfully read the table. > > > > > > > > > > > > For the location keyword, as Eric has pointed out, we can > > potentially > > > > > have > > > > > > a reserved key for the properties. However, location is a common > > > > > > enough key among various table formats, which worths a dedicated > > key > > > to > > > > > > help store and load the information in a more straightforward > > > > > > way. For things that are specific to one or two formats, I think > > it > > > > > makes > > > > > > more sense to use a reserved property key. > > > > > > > > > > > > As a reference, in Iceberg, the CreateTable request and > > TableMetadata > > > > > does > > > > > > have an explicit location key in the spec. For write.data.path > > > > > > and write.metadata.path, they are passed as properties today. > > > > > > > > > > > > Best Regards, > > > > > > Yun > > > > > > > > > > > > > > > > > > On Wed, May 7, 2025 at 3:54 PM Dmitri Bourlatchkov < > > di...@apache.org > > > > > > > > > > wrote: > > > > > > > > > > > >> Another point: I'm pretty sure sooner or later users will want > to > > > move > > > > > >> their data to some other location. As an option users may want > to > > > > write > > > > > >> new > > > > > >> files into another location but keep old files in place. > > > > > >> > > > > > >> Also: if the location is a URI, how do we deal with s3 vs. s3a > for > > > > > >> example? > > > > > >> > > > > > >> In Iceberg it is quite common for different engines to use > > different > > > > > >> access > > > > > >> tools, which often leads to different URI schemes. > > > > > >> > > > > > >> Cheers, > > > > > >> Dmitri. > > > > > >> > > > > > >> On Wed, May 7, 2025 at 6:46 PM Eric Maynard < > > > eric.w.mayn...@gmail.com > > > > > > > > > > >> wrote: > > > > > >> > > > > > >> > All good questions Dmitri — I’m especially interested in the > > first > > > > one > > > > > >> as > > > > > >> > from what I understand Iceberg tables can have metadata and > data > > > at > > > > > two > > > > > >> > different paths that we need to vend credentials for. > > > > > >> > > > > > > >> > For iceberg tables, we just use special properties to track > > these > > > > > >> > locations. I wonder if we couldn’t do the same for generic > > tables. > > > > > >> > > > > > > >> > On Wed, May 7, 2025 at 3:42 PM Dmitri Bourlatchkov < > > > > di...@apache.org> > > > > > >> > wrote: > > > > > >> > > > > > > >> > > Hi Yun, > > > > > >> > > > > > > > >> > > Please clarify the meaning of the value of the new location > > > > > attribute. > > > > > >> > > > > > > > >> > > - Is is one value or many? > > > > > >> > > - Is it a URI? > > > > > >> > > - Does it point to any particular file? > > > > > >> > > - Is it a common prefix of all files within a table? > > > > > >> > > - What happens when a value does not match these > expectation? > > > > > >> > > > > > > > >> > > Thanks, > > > > > >> > > Dmitri. > > > > > >> > > > > > > > >> > > On 2025/05/07 21:50:19 yun zou wrote: > > > > > >> > > > Hi folks, > > > > > >> > > > > > > > > >> > > > I would like to propose to add an optional `location` > field > > to > > > > > >> > > > CreateGenricTable Request and LoadGenericTable response. > > > > > >> > > > > > > > > >> > > > The `location` is the location for the table, which is > > common > > > to > > > > > >> most > > > > > >> > > table > > > > > >> > > > formats including Iceberg, Delta, Hudi, csv, parquet etc. > > The > > > > > >> location > > > > > >> > > > information is critical for loading the table at engine > > side, > > > > > >> having a > > > > > >> > > > dedicated keyword could help improve the robustness for > > cross > > > > > engine > > > > > >> > > > sharing, instead of relying on the properties passed by > the > > > > client > > > > > >> > side. > > > > > >> > > > > > > > > >> > > > Furthermore, this information is also required to provide > > > > > credential > > > > > >> > > > vending capabilities later. > > > > > >> > > > > > > > > >> > > > Here is the PR for adding the spec: > > > > > >> > > > https://github.com/apache/polaris/pull/1543 > > > > > >> > > > > > > > > >> > > > Looking forward to your reply and feedback! > > > > > >> > > > > > > > > >> > > > Best Regards, > > > > > >> > > > Yun > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > > > > > > > > > > > > > > > > >
