Thank you Julian for the information. Julian Hyde <jhyde.apa...@gmail.com> 于2022年8月6日周六 14:20写道：
> I believe that subscriber lists are only available to mailing list > administrators. > > I know that Pranav is not subscribed because, as a moderator, I receive an > email each time he posts. > > You can find out about (and manage) your own subscription status by > emailing dev-h...@calcite.apache.org. > > Julian > > > On Aug 5, 2022, at 9:06 PM, Benchao Li <libenc...@apache.org> wrote: > > > > Julian, > > > > Could you teach me how to know whether someone has subscribed to the ML > or > > not quickly? > > I searched this question and found[1], but this way is not very handy. > > > > [1] > > > https://wiki.openoffice.org/wiki/Documentation/FAQ/General/How_to_know_if_a_user_is_subscribed_to_a_mailing_list > > > > Benchao Li <libenc...@apache.org> 于2022年8月6日周六 11:56写道： > > > >> Pranav, > >> > >> You can reference Calcite adaptors implementation, such as JDBC > >> Adaptor[1], MongoDB Adaptor[2]. > >> Their implementation allows pushing down operations (RelNode) to the > >> adapter as much as possible, and the left RelNodes will be implemented > >> using Enumerable Convention. > >> > >> We have a Converter[3] concept which makes this possible. The converter > >> node allows multiple Conventions in a single query. This also answers > your > >> second question. > >> There is a talk[4] about this, it's very helpful for understanding this > >> concept. > >> > >> [1] > >> > https://github.com/apache/calcite/blob/main/core/src/main/java/org/apache/calcite/adapter/jdbc/JdbcToEnumerableConverter.java > >> [2] > >> > https://github.com/apache/calcite/blob/main/mongodb/src/main/java/org/apache/calcite/adapter/mongodb/MongoToEnumerableConverter.java > >> [3] > >> > https://github.com/apache/calcite/blob/main/core/src/main/java/org/apache/calcite/rel/convert/Converter.java > >> [4] > >> > https://calcite.apache.org/community/#fast-federated-sql-with-apache-calcite > >> > >> Julian Hyde <jhyde.apa...@gmail.com> 于2022年8月6日周六 02:06写道： > >> > >>> Pranav, > >>> > >>> Please subscribe to this list. You have asked several questions, > received > >>> replies, not acknowledged those replies, and asked further questions. > Also, > >>> since you are not subscribed, each email you post has to go through > manual > >>> moderation. > >>> > >>> Julian > >>> > >>>> On Aug 5, 2022, at 9:38 AM, Pranav Deshpande < > >>> deshpande.v.pra...@gmail.com> wrote: > >>>> > >>>> Dear Apache Calcite Team, > >>>> I have 2 questions. > >>>> > >>>> --------------------------------- > >>>> 1. > >>>> > >>>> There are plenty of examples on how to push down projects and filters > >>> into > >>>> the leaf nodes (tablescans). > >>>> > >>>> However, I could not find any examples to push down joins to > TableScans > >>> (or > >>>> joins+filters+projects etc.) [this is helpful for data federation I > >>> think]. > >>>> > >>>> On the mailing list, many folks are suggesting that I use Drill. > >>> However, > >>>> the purpose of my exercise is to gain knowledge about DBMS and Query > >>>> processing etc. > >>>> > >>>> I tried debugging open source engines that use Calcite (Drill, Druid, > >>> Trino > >>>> etc.) but was completely lost. > >>>> > >>>> Any examples/pointers/guidance around the same would be appreciated. > >>>> Example, pushing down a join with a filter to a DBMS(consider jdbc > >>>> msql etc.) > >>>> > >>>> ------------------------------------- > >>>> 2. > >>>> > >>>> The 2nd question I have is regarding conventions and different DBMS. > The > >>>> cluster has a method to replace the trait convention(Bindable,JDBC > >>> etc.), > >>>> and then we optimize and get the physical plan. > >>>> > >>>> But imagine I have both the MYSQL JDBC convnction and a cassandra > >>>> convention and some user is trying to query both tables. > >>>> > >>>> Something like "SELECT users.username, specialdata.country from > >>>> cassandraDB.user join mysqlDB.specialdata ON users.id > >>> =specialdata.userid" > >>>> > >>>> Now, how will calcite do the optimization here? The planner is not > >>>> accepting 2 different conventions. > >>>> > >>>> Thanks & Regards, > >>>> Pranav > >>> > >>> > >> > >> -- > >> > >> Best, > >> Benchao Li > >> > > > > > > -- > > > > Best, > > Benchao Li > -- Best, Benchao Li
