This is a bit of a tangent from the original discussion about Substrait integration.
Flight SQL would definitely benefit from transaction RPC commands for building bridge drivers. I'm also wondering if there should be an RPC call to cancel a running query, as opposed to just having the client terminate streams. This would allow a multi-process application to cancel work across processes. On Thu, Jun 30, 2022 at 1:35 PM David Li <lidav...@apache.org> wrote: > Reviving this discussion: would people be interested in seeing a > sketched-out CommandSubstraitQuery et. al.? > > Additionally, while working on ADBC, I realized: does Flight SQL need > explicit Commit/Rollback commands? This would presumably be necessary if we > want to build ODBC/JDBC drivers on top, since those standards have explicit > commands, and Flight SQL doesn't have the luxury of a driver to issue > database-specific SQL to implement these. > > It would also then be good to make explicit the statefulness of > connections in Flight SQL. While that is sort of an obvious constraint, it > is at odds with how gRPC is usually used (especially in the presence of > load balancing). > > On Sun, Mar 6, 2022, at 14:44, Gavin Ray wrote: > > Got it, thank you David! > > I started prototyping the implementation last night, hopefully I will > make > > some good progress and have something basic functioning soon. > > > > RE: The metadata thing -- I think both Calcite and Teiid have solid > > interfaces for defining what capabilities a datasource has. > > > https://github.com/teiid/teiid/blob/8e9057a46be009d68b2d67701781f1f8c175baa7/api/src/main/java/org/teiid/translator/ExecutionFactory.java#L349-L1528 > > > > It's probably not possible to make something universal, but it seems like > > you could get pretty close to most common functionality/capabilities > > > > > > On Sat, Mar 5, 2022 at 11:48 PM Kyle Porter <ky...@bitquilltech.com > .invalid> > > wrote: > > > >> Yes, we should, where possible, avoid any one of metadata. This is where > >> other standards fail in that applications must be custom built for each > >> data source, if we standardize the metadata then applications can at > least > >> be built to adapt. > >> > >> On Sat., Mar. 5, 2022, 6:54 p.m. David Li, <lidav...@apache.org> wrote: > >> > >> > Yes, GetSqlInfo reserves a range of metadata IDs for Flight SQL's > use, so > >> > the application can use others for its own purposes. That said if they > >> seem > >> > commonly applicable maybe we should try to standardize them. > >> > > >> > I think what you are doing should be reasonable. You may not need > _all_ > >> of > >> > the capabilities in Flight SQL for this (e.g. all the various metadata > >> > calls, or prepared statements, perhaps) but I don't see why it > wouldn't > >> > work for you. > >> > > >> > On Fri, Mar 4, 2022, at 19:03, Gavin Ray wrote: > >> > > To touch on the question about supported features -- is it possible > to > >> > > advertise arbitrary/custom "capabilites" in GetSqlInfo? > >> > > Say that you want to represent some set of behaviors that FlightSQL > >> > > services can support. > >> > > > >> > > Stuff like "Supports grouping by multiple distinct aggregates", > >> "Supports > >> > > self-joins on aliased tables" etc > >> > > This is going to be unique to each implementation, but I couldn't > >> > determine > >> > > whether there was a way to express arbitrary capabilities > >> > > > >> > > Also, in case it's helpful I put together an ASCII diagram of what > I'm > >> > > trying to do with FlightSQL > >> > > If anyone has a moment, would appreciate input on whether it's > >> feasible/a > >> > > good idea > >> > > > >> > > https://pastebin.com/raw/VF2r0F3f > >> > > > >> > > Thank you =) > >> > > > >> > > > >> > > On Fri, Mar 4, 2022 at 2:37 PM David Li <lidav...@apache.org> > wrote: > >> > > > >> > >> We could also add say CommandSubstraitQuery as a distinct message, > and > >> > >> older servers would just reject it as an unknown request type. > >> > >> > >> > >> -David > >> > >> > >> > >> On Fri, Mar 4, 2022, at 17:01, Micah Kornfield wrote: > >> > >> >> > >> > >> >> 1. How does a server report that it supports each command type? > >> > Initial > >> > >> >> thought is a property in GetSqlInfo. > >> > >> > > >> > >> > > >> > >> > This sounds reasonable. > >> > >> > > >> > >> > > >> > >> >> What happens to client code written prior to changing the > command > >> > type > >> > >> >> to be a oneOf field? Same for servers. > >> > >> > > >> > >> > > >> > >> > It is transparent from older clients (I'm 99% sure the wire > protocol > >> > >> > doesn't change). Servers is a little harder. The one saving > grace > >> > is I > >> > >> > don't think an empty/not-present SQL string would be something > most > >> > >> servers > >> > >> > could handle, so they would probably error with something that > while > >> > >> > not-obvious would give a clue to the clients (but hopefully this > >> would > >> > >> be a > >> > >> > non-issue because the capabilities would be checked for clients > >> > wishing > >> > >> to > >> > >> > to use this feature first). > >> > >> > > >> > >> > -Micah > >> > >> > > >> > >> > On Fri, Mar 4, 2022 at 1:50 PM James Duong < > jam...@bitquilltech.com > >> > >> .invalid> > >> > >> > wrote: > >> > >> > > >> > >> >> It sounds like an interesting and useful project to use > Subtstrait > >> > as an > >> > >> >> alternative to SQL strings. > >> > >> >> > >> > >> >> Important aspects to spec out are: > >> > >> >> 1. How does a server report that it supports each command type? > >> > Initial > >> > >> >> thought is a property in GetSqlInfo. > >> > >> >> 2. What happens to client code written prior to changing the > >> command > >> > >> type > >> > >> >> to be a oneOf field? Same for servers. > >> > >> >> More generally, how should backward compatibility work, and what > >> > should > >> > >> >> happen if a client sends an unsupported > >> > >> >> command type to a server. > >> > >> >> 3. Should inputs to catalog RPC calls also accept Substrait > >> > structures? > >> > >> >> > >> > >> >> On Thu, Mar 3, 2022 at 11:00 PM Gavin Ray < > ray.gavi...@gmail.com> > >> > >> wrote: > >> > >> >> > >> > >> >> > @James Duong <jam...@bitquilltech.com> > >> > >> >> > > >> > >> >> > You are absolutely right, I realized this and confirmed > whether > >> > this > >> > >> >> > would be possible with Jacques to double-check. > >> > >> >> > It would amount to what I might call "dollar-store Substrait." > >> It's > >> > >> not > >> > >> >> > elegant or a good solution, but definitely presents a good > >> > duct-tape > >> > >> hack > >> > >> >> > and is a crafty idea. > >> > >> >> > > >> > >> >> > I agree with Jacques -- when you think about FlightSQL, what > you > >> > are > >> > >> >> > attempting with a query isn't necessarily SQL, but a general > >> > >> data-compute > >> > >> >> > operation. > >> > >> >> > SQL just so happens to be a fairly universal way to express > them, > >> > >> with an > >> > >> >> > ANSI standard, but FlightSQL doesn't recognize any particular > >> > subset > >> > >> of > >> > >> >> it > >> > >> >> > and for all intents and purposes it doesn't matter what the > >> > operation > >> > >> >> > string contains. > >> > >> >> > > >> > >> >> > Substrait would make a fantastic logical next-feature because > >> it's > >> > >> >> > targeted as a specification for expressing relational algebra > and > >> > >> >> > data-compute operations > >> > >> >> > This more-or-less equates to SQL strings (in my mind at least) > >> > with a > >> > >> >> much > >> > >> >> > better toolkit and Dev UX. If there is anything I can do to > help > >> > move > >> > >> >> this > >> > >> >> > forward, please let me know because I am extremely motivated > to > >> do > >> > so. > >> > >> >> > > >> > >> >> > @David Li <git...@lidavidm.me> > >> > >> >> > > >> > >> >> > Also agreed. Substrait is put together by folks much smarter > than > >> > >> myself, > >> > >> >> > and if I had to hedge my bets, I'd put money on it being the > >> > future of > >> > >> >> > data-compute interop. > >> > >> >> > I would love nothing more than to adopt this technology and > push > >> it > >> > >> >> along. > >> > >> >> > > >> > >> >> > Your project does sound interesting - basically, it sounds > like a > >> > >> tabular > >> > >> >> >> data storage service with query pushdown? > >> > >> >> >> > >> > >> >> > > >> > >> >> > Yeah this is more or less the details of it (my personal > email, > >> > with > >> > >> >> > discretion assumed, is always open) > >> > >> >> > > >> > >> >> > Imagine an environment where a backend wants to advertise some > >> > kind of > >> > >> >> > schema/data catalog > >> > >> >> > > >> > >> >> > And then a central service introspects these backends, and > >> > dynamically > >> > >> >> > generates an API from the data catalogues/schemas, where > requests > >> > get > >> > >> >> > proxied to the underlying backend service for each schema to > >> > actually > >> > >> be > >> > >> >> > executed > >> > >> >> > > >> > >> >> > In text, the flow would look something like: > >> > >> >> > > >> > >> >> > > >> > >> >> > <----> Data Provider Backend 0 > >> > >> >> > Client <-----> Central Service <---> Generated API <----> > >> > >> Data-Provider > >> > >> >> > Backend 1 > >> > >> >> > > >> > >> >> > <----> Data Provider Backend 2 > >> > >> >> > > >> > >> >> > > >> > >> >> > > >> > >> >> > On Thu, Mar 3, 2022 at 5:52 PM David Li <lidav...@apache.org> > >> > wrote: > >> > >> >> > > >> > >> >> >> Gavin, thanks for sharing. I'm not so sure you'll find an > >> > >> alternative to > >> > >> >> >> Substrait, at least one that isn't even more nascent or one > >> that's > >> > >> very > >> > >> >> >> tied to a particular language, so perhaps it might be better > to > >> > get > >> > >> >> >> involved in Substrait and see if it suits your needs? > >> Convincing a > >> > >> team > >> > >> >> to > >> > >> >> >> try something new can be hard, though, and it is somewhat of > a > >> > moving > >> > >> >> >> target - but Flight SQL is in a similar spot, I think, as > it's > >> > still > >> > >> >> >> getting enhancements. > >> > >> >> >> > >> > >> >> >> Your project does sound interesting - basically, it sounds > like > >> a > >> > >> >> tabular > >> > >> >> >> data storage service with query pushdown? > >> > >> >> >> > >> > >> >> >> On Thu, Mar 3, 2022, at 19:58, Jacques Nadeau wrote: > >> > >> >> >> > James, I agree that you could use JSON but that feels a bit > >> > hacky > >> > >> >> >> > (mis-use > >> > >> >> >> > of the paradigm). Instead, I'd really like to do something > >> like > >> > >> David > >> > >> >> is > >> > >> >> >> > suggesting: support Substrait as an alternative to a SQL > >> string. > >> > >> >> >> > Something like this: > >> > >> >> >> > > >> > >> >> >> > >> > >> >> > >> > >> > >> > > >> > https://github.com/jacques-n/arrow/commit/e22674fa882e77c2889cf95f69f6e3701db362bc > >> > >> >> >> > > >> > >> >> >> > It would be great if someone wanted to pick this up. It > would > >> > be a > >> > >> >> nice > >> > >> >> >> > enhancement to FlightSQL (and provide a structured way to > >> > express > >> > >> >> >> > operations). > >> > >> >> >> > > >> > >> >> >> > > >> > >> >> >> > > >> > >> >> >> > On Thu, Mar 3, 2022 at 4:56 PM James Duong < > >> > >> jam...@bitquilltech.com > >> > >> >> >> .invalid> > >> > >> >> >> > wrote: > >> > >> >> >> > > >> > >> >> >> >> In the same way that you could write an ODBC driver that > >> takes > >> > in > >> > >> >> text > >> > >> >> >> >> that's not SQL, you could write a Flight SQL server that > >> takes > >> > in > >> > >> >> text > >> > >> >> >> >> that's JSON. > >> > >> >> >> >> Flight SQL doesn't parse the query, so you could create > >> > commands > >> > >> that > >> > >> >> >> are > >> > >> >> >> >> just JSON text. > >> > >> >> >> >> > >> > >> >> >> >> Is that the only bit you need, Gavin? > >> > >> >> >> >> > >> > >> >> >> >> On Thu, Mar 3, 2022 at 4:26 PM Gavin Ray < > >> > ray.gavi...@gmail.com> > >> > >> >> >> wrote: > >> > >> >> >> >> > >> > >> >> >> >> > I am enthusiastic about Substrait and have followed it's > >> > >> progress > >> > >> >> >> eagerly > >> > >> >> >> >> > =D > >> > >> >> >> >> > > >> > >> >> >> >> > When I presented it as a tentative option, there were > >> > >> reservations > >> > >> >> >> >> because > >> > >> >> >> >> > of the project/spec being young and the functionality > still > >> > >> being > >> > >> >> >> >> > fleshed out. > >> > >> >> >> >> > I think if I were having this conversation in say, 8-16 > >> > months, > >> > >> it > >> > >> >> >> would > >> > >> >> >> >> > have been an easy choice, no doubt. > >> > >> >> >> >> > > >> > >> >> >> >> > On a public mailing list (and I can share more details > in > >> > >> private > >> > >> >> if > >> > >> >> >> >> you're > >> > >> >> >> >> > curious), the gist of it is this: > >> > >> >> >> >> > > >> > >> >> >> >> > Some well-defined/backed-by-mature tech solution for > >> > expressing > >> > >> >> data > >> > >> >> >> >> > compute operations between services would be a useful > thing > >> > to > >> > >> have > >> > >> >> >> >> > (Especially if it's language-agnostic) > >> > >> >> >> >> > > >> > >> >> >> >> > The goal is for an "implementing service" to have: > >> > >> >> >> >> > - An introspectable schema (IE, "describe yourself to > me") > >> > >> >> >> >> > - A query/operation execution endpoint (IE: "perform > this > >> > >> operation > >> > >> >> >> on > >> > >> >> >> >> your > >> > >> >> >> >> > data") > >> > >> >> >> >> > > >> > >> >> >> >> > With FlightSQL this is possible I believe, but it > requires > >> > the > >> > >> >> >> operation > >> > >> >> >> >> to > >> > >> >> >> >> > be expressed as a SQL string which isn't ideal. > >> > >> >> >> >> > > >> > >> >> >> >> > Working with some programmatic, structured object that > has > >> > the > >> > >> same > >> > >> >> >> >> > semantics ("Logical Plan", or whatnot) as a SQL query > would > >> > >> have, > >> > >> >> >> would > >> > >> >> >> >> be > >> > >> >> >> >> > a better experience > >> > >> >> >> >> > (Jacques is on to something here!) > >> > >> >> >> >> > > >> > >> >> >> >> > This interface between services would be somewhat the > >> > >> equivalent of > >> > >> >> >> an > >> > >> >> >> >> > "SDK", so it would be nice to have a strongly-typed > library > >> > for > >> > >> >> >> >> expressing > >> > >> >> >> >> > and building-up query/data-compute ops. > >> > >> >> >> >> > > >> > >> >> >> >> > > >> > >> >> >> >> > On Thu, Mar 3, 2022 at 3:17 PM David Li < > >> lidav...@apache.org > >> > > > >> > >> >> wrote: > >> > >> >> >> >> > > >> > >> >> >> >> > > You probably want Substrait: https://substrait.io/ > >> > >> >> >> >> > > > >> > >> >> >> >> > > Which is being worked on by several people, including > >> Arrow > >> > >> >> >> community > >> > >> >> >> >> > > members. > >> > >> >> >> >> > > > >> > >> >> >> >> > > It might be interesting to generalize Flight SQL to > >> include > >> > >> >> >> support for > >> > >> >> >> >> > > Substrait. I'm curious what your application, if > you're > >> > able > >> > >> to > >> > >> >> >> share > >> > >> >> >> >> > more. > >> > >> >> >> >> > > > >> > >> >> >> >> > > -David > >> > >> >> >> >> > > > >> > >> >> >> >> > > On Thu, Mar 3, 2022, at 18:05, Gavin Ray wrote: > >> > >> >> >> >> > > > Hiya, > >> > >> >> >> >> > > > > >> > >> >> >> >> > > > I am drafting a proposal for a way to enable > services > >> to > >> > >> >> express > >> > >> >> >> data > >> > >> >> >> >> > > > compute operations to each other. > >> > >> >> >> >> > > > > >> > >> >> >> >> > > > However I think it'll be difficult to get buy-in if > the > >> > only > >> > >> >> >> >> > > representation > >> > >> >> >> >> > > > for queries is as SQL strings. > >> > >> >> >> >> > > > > >> > >> >> >> >> > > > Is there any kind of lower-level API that can be > used > >> to > >> > >> >> express > >> > >> >> >> >> > > operations? > >> > >> >> >> >> > > > > >> > >> >> >> >> > > > IE instead of "SELECT name FROM user" > >> > >> >> >> >> > > > > >> > >> >> >> >> > > > A structured representation like: > >> > >> >> >> >> > > > { > >> > >> >> >> >> > > > "op": "query", > >> > >> >> >> >> > > > "schema": "user", > >> > >> >> >> >> > > > "project": ["name"] > >> > >> >> >> >> > > > } > >> > >> >> >> >> > > > > >> > >> >> >> >> > > > Or maybe this is a bad idea/doesn't make sense? > >> > >> >> >> >> > > > > >> > >> >> >> >> > > > Thank you =) > >> > >> >> >> >> > > > >> > >> >> >> >> > > >> > >> >> >> >> > >> > >> >> >> >> > >> > >> >> >> >> -- > >> > >> >> >> >> > >> > >> >> >> >> *James Duong* > >> > >> >> >> >> Lead Software Developer > >> > >> >> >> >> Bit Quill Technologies Inc. > >> > >> >> >> >> Direct: +1.604.562.6082 | jam...@bitquilltech.com > >> > >> >> >> >> https://www.bitquilltech.com > >> > >> >> >> >> > >> > >> >> >> >> This email message is for the sole use of the intended > >> > >> recipient(s) > >> > >> >> >> and may > >> > >> >> >> >> contain confidential and privileged information. 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If you are not > the > >> > >> >> intended recipient, please contact the sender by reply email and > >> > destroy > >> > >> >> all copies of the original message. Thank you. > >> > >> >> > >> > >> > >> > > >> > -- *James Duong* Lead Software Developer Bit Quill Technologies Inc. Direct: +1.604.562.6082 | jam...@bitquilltech.com https://www.bitquilltech.com This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. Thank you.
