I am still happy to implement them. As far as adapting the log2 function is concerned, at present I may just not be able to guarantee that log2(0) returns null, and I have encountered some stuck points here. But you can see that I've raised two other jira issues [CALCITE-6259] <https://issues.apache.org/jira/browse/CALCITE-6259>， [CALCITE-6277] <https://issues.apache.org/jira/browse/CALCITE-6277> about this, and I'm going to want to fix the jira issue that I raised, because that's what I found, and I should do it. This is why I keep saying that I can merge this jira first. Regarding extreme scenarios, I will continue to adapt the type of discourse in the next jira, because I am not sure whether my current writing method is appropriate in the next jira.
Cancai Cai <can...@apache.org> 于2024年2月23日周五 09:50写道： > Hi, everyone > Thank you very much for your answers. In fact, my doubts may not only be > about adapting log2 (function), as I have discovered a lot when adapting > log2 functions, such as log10(0) about the difference in return values of > mysql and postgres, about calcite Regarding the handling of infinities, I > don't know why I haven't discovered them before. As clay said, calcite may > have had its own set of standards before, but I may not be clear about > this. I hope that calcite’s return value of the math function in certain > calculation situations will meet the requirements of mathematics or SQL. > rule. If mysql is lazy from the beginning, should we still follow it > instead of just adapting to an extreme situation? > > Best wishes. > Cancai Cai > > On 2024/02/23 00:45:13 Tanner Clary wrote: > > I feel like I'm missing something about this whole issue. We have > > implemented so many functions that there's probably an existing pattern > for > > just about any issue with dialect parity we encounter. What's the core > > problem? What behavior is so difficult to emulate and why? Caican let me > > know if you want to pair I'm happy to manage the edge cases if you want. > > > > Tanner > > > > On Thu, Feb 22, 2024 at 4:34 PM Julian Hyde <jhyde.apa...@gmail.com> > wrote: > > > > > I agree. https://issues.apache.org/jira/browse/CALCITE-6224 and its > > > accompanying PR muddies the waters because it also mentions Spark, > Postgres > > > and “many databases”. The case should state that the function is > consistent > > > with MySQL and returns NULL if the argument is non-positive. > > > > > > > On Feb 22, 2024, at 4:24 PM, Mihai Budiu <mbu...@gmail.com> wrote: > > > > > > > > In the case of log2 it's simple, because the documentation says that > it > > > comes from the MySQL dialect. So there is a spec and a golden > > > implementation to compare against. > > > > > > > > I certainly won't object to implementing a separate log2 function > that > > > is undefined for 0 and negative values (i.e., can return any value for > such > > > arguments), let's just not pretend it's the MySQL function. > > > > > > > > Mihai > > > > ________________________________ > > > > From: Julian Hyde <jhyde.apa...@gmail.com> > > > > Sent: Thursday, February 22, 2024 4:05 PM > > > > To: dev@calcite.apache.org <dev@calcite.apache.org> > > > > Subject: Re: Some questions about calcite > > > > > > > > But what is the spec of the LOG2 function? It’s not in the SQL > standard. > > > So, we need to write our own spec. We can say that LOG2(0) returns 42, > if > > > we wish, and go implement our own spec. > > > > > > > > Yes, Calcite is a compiler, but it is also a standard library, and > it is > > > also an extended library. LOG2 is in the latter category. If you, as a > > > vendor, don’t trust the implementation of LOG2 then you can exclude it > from > > > your distribution. > > > > > > > > As an open source project we have to BOTH improve the quality of our > > > core and lower the barrier to contributions to the non-core code. We > have > > > to recognize that not everything is the same standard. And I think > vendors, > > > like your company, who want to deliver a high-quality experience > should put > > > barriers around what features are trusted. > > > > > > > > Julian > > > > > > > >> On Feb 22, 2024, at 3:42 PM, Mihai Budiu <mbu...@gmail.com> wrote: > > > >> > > > >> If we can't even implement correctly the log2 function according to > its > > > spec, there is no hope that we will implement anything correctly. > > > >> > > > >> I am not a QA person, but I am spending more than 50% of my time > > > diagnosing and fixing bugs in Calcite. It's not fun. I would rather > > > implement interesting new functionality. But I cannot tell a user of > our > > > tools "I have no idea whether the results you get using this tool will > be > > > correct. If you are lucky, they will be, don't worry about corner > cases." > > > Our goal is to use Calcite in a production environment. If Calcite is > > > designed to be just a research tool, maybe we should make that clear. > > > >> > > > >> There are fundamental bugs in Calcite which have been there for a > > > decade. Even basic things like arithmetic casts are still incorrect. > Which > > > is proof that once a bug is in, people are not incentivized to fix > them. We > > > should not let bugs in deliberately. They may essentially never get > fixed. > > > >> > > > >> I don't think a compiler can cut any corners. The compiler is the > > > foundation of an entire software ecosystem. If the foundation is > broken, > > > everything crumbles. > > > >> > > > >> Mihai > > > >> > > > >> ________________________________ > > > >> From: Julian Hyde <jhyde.apa...@gmail.com> > > > >> Sent: Thursday, February 22, 2024 3:28 PM > > > >> To: dev@calcite.apache.org <dev@calcite.apache.org> > > > >> Subject: Re: Some questions about calcite > > > >> > > > >> Don’t let the perfect be the enemy of the good. Or as they say in > open > > > source, “Release early and often”. > > > >> > > > >> Just about everyone who wants a LOG2 function is intending to apply > it > > > to positive numbers. So they won’t notice, or care, that the function > > > doesn’t do exactly what they expected when you apply it to zero. You > should > > > release a LOG2 function that does the right thing for the positive > numbers, > > > if it’s less effort than handling all non-negative numbers. > > > >> > > > >> Don’t listen too much to the QA folks. Their job is to find the > corner > > > cases. But they forget that the corner cases are usually not as > important > > > as the core cases. So, let the QA folks log bugs (or you can a log > > > yourself, when you submit an imperfect implementation). Just release > early > > > and often. > > > >> > > > >> Also, note that the implementation of a function in Java, so that it > > > can be executed by Calcite, does not have to be the *only* > implementation. > > > It is often better to have the JDBC adapter push the function down. > That is > > > exactly what Bertil is doing for geospatial functions in > > > https://issues.apache.org/jira/browse/CALCITE-6239, and Tanner is > looking > > > at making a map so that we know which SQL dialects can implement which > > > functions. > > > >> > > > >> Julian > > > >> > > > >> > > > >> > > > >>> On Feb 22, 2024, at 6:11 AM, Cancai Cai <can...@apache.org> wrote: > > > >>> > > > >>> When I was working CALCITE-6224 > > > >>> <https://issues.apache.org/jira/browse/CALCITE-6224>, I > encountered > > > some > > > >>> problems and I always had some doubts in my heart. > > > >>> I thought about it for a long time, maybe I think I already > understand > > > the > > > >>> doubts in my heart. > > > >>> > > > >>> As @mihaibudiu said, Java grammar has its own type rules, and SQL > has > > > its > > > >>> own type rules. What calcite currently does is to use Java syntax > to > > > adapt > > > >>> to the SQL rules of each database to complete execution > optimization. > > > In > > > >>> some extreme scenarios, the SQL rules of various databases are > > > >>> inconsistent. Calcite > > > >>> needs to be sure to adapt to these extreme situations. But, I > mean, if > > > one > > > >>> day, for example, mysql returns the result of log10(0) as an error > > > instead > > > >>> of null, then does calcite need to adapt to the new version of > mysql? > > > If it > > > >>> adapts to the new version of mysql, does calcite still need to > adapt > > > to the > > > >>> old version of mysql? It seems to me that this may be a paradox. > > > Because in > > > >>> my opinion, it is very difficult to 100% adapt to the SQL dialect > of > > > all > > > >>> databases, because different dialects of each database need to be > > > >>> considered, and there may even be differences between versions of > > > different > > > >>> versions of databases. > > > >>> > > > >>> Can anyone explain it to me? I would be very grateful. > > > >> > > > > > > > > > > > > >
