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. 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. > >> >> >> >> > >> >> >> > >> >> > > >> >> > >> >> -- > >> >> > >> >> *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. > >> >> > >> >
