Igor. > The main issue - there is no *selection*.
1. I don't remember community decision about this. 2. We should avoid to make such long-term decision so quickly. We done this kind of decision with H2 and come to the point when we should review it. > 1) Implementing white papers from scratch > 2) Adopting Calcite to our needs. The third option don't fix issues we have with H2. The fourth option I know is using spark-catalyst. What is wrong with writing engine from scratch? I ask you to start with engine requirements. Can we, please, discuss it? > If you have an alternative - you're welcome, I'll gratefully listen to you. We have alternative for now - H2 based engine. > The main question isn't "WHAT" but "HOW" - that's the discussion topic from > my point of view. When we make a decision about engine we can discuss roadmap for replacement. One more time - replacement of SQL engine to some more customizable make sense for me. But, this kind of decisions need carefull discussion. В Пт, 27/09/2019 в 17:08 +0300, Seliverstov Igor пишет: > 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! > >
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