Nikolay, The main issue - there is no *selection*.
There is a field of knowledge - relational algebra, which describes how to transform relational expressions saving their semantics, and a couple of implementations (Calcite is only one written in Java). There are only two alternatives: 1) Implementing white papers from scratch 2) Adopting Calcite to our needs. The second way was chosen by several other projects, there is experience, there is a list of known issues (like using indexes) so, almost everything is already done for us. Implementing a planner is a big deal, I think anybody understands it there. That's why our proposal to reuse others experience is obvious. If you have an alternative - you're welcome, I'll gratefully listen to you. The main question isn't "WHAT" but "HOW" - that's the discussion topic from my point of view. Regards, Igor > 27 сент. 2019 г., в 16:37, Nikolay Izhikov <nizhi...@apache.org> написал(а): > > Roman. > >> Nikolay, Maxim, I understand that our arguments may not be as obvious >> for you as it obvious for SQL team. So, please arrange your questions in >> a more constructive way. > > What is SQL team? > I only know Ignite community :) > > Please, share you knowledge in IEP. > I want to join to the process of engine *selection*. > It should start with the requirements to such engine. > Can you write it in IEP, please? > > My point is very simple: > > 1. We made the wrong decision with H2 > 2. We should make a well-thought decision about the new engine. > >> How many tickets would satisfy you? > > You write about "issueS" with the H2. > All I see is one open ticket. > IEP doesn't provide enough information. > So it's not about the number of tickets, it's about > >> These two points (single map-reduce execution and inflexible optimizer) >> are the main problems with the current engine. > > We may come to the point when Calcite(or any other engine) brings us third > and other "main problems". > This is how it happens with H2. > > Let's start from what we want to get with the engine and move forward from > this base. > What do you think? > > > > В Пт, 27/09/2019 в 16:15 +0300, Roman Kondakov пишет: >> Maxim, Nikolay, >> >> I've listed two issues which show the ideological flaws of the current >> engine. >> >> 1. IGNITE-11448 - Open. This ticket describes the impossibility of >> executing queries which can not be fit in the hardcoded one pass >> map-reduce paradigm. >> >> 2. IGNITE-6085 - Closed (won't fix) - This ticket describes the second >> major problem with the current engine: H2 query optimizer is very >> primitive and can not perform many useful optimizations. >> >> These two points (single map-reduce execution and inflexible optimizer) >> are the main problems with the current engine. It means that our engine >> is currently suitable for execution only a very limited subset of the >> typical SQL queries. For example it can not even run most of the TPC-H >> benchmark queries because they don't fit to the simple map-reduce paradigm. >> >>> All I see is links to two tickets: >> >> How many tickets would satisfy you? I named two. And it looks like it is >> not enough from your point of view. Ok, so how many is enough? The set >> of problems caused by listed above tickets is infinite, therefore I can >> not create a ticket for each of them. >>> Tech details also should be added. >> >> Tech details are in the tickets. >> >>> We can't discuss such a huge change as an execution engine replacement with >>> descrition like: >>> "No data co-location control, i.e. arbitrary data can be returned silently" >>> or >>> "Low control on how query executes internally, as a result we have limited >>> possibility to implement improvements/fixes." >> >> Why not? Don't you understand these problems? Or you don't think this is >> a problem? >> >>> Let's make these descriptions more specific. >> >> What do you mean by "more specific"? What is the criteria of the >> specific description? >> >> >> >> Nikolay, Maxim, I understand that our arguments may not be as obvious >> for you as it obvious for SQL team. So, please arrange your questions in >> a more constructive way. >> >> Thank you!
