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How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

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Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#31
post #25

I recently created a database engine (exosql [1]), only query and no storage. It uses postgres-like foreign data wrappers to get all data. It's not valid for big datasets, as it stores all in memory (or maybe it is?), but as a learning experience has been amazing to think and develop a real database: planner, executor, choose algorithms, implement features as lateral joins and so on. I will definetly listen very care…

Any books/lectures/articles you followed?

Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#32

Any video filter experts here? Request to any video filter expert ------------------------------------ I started watching this. The slides are unreadable but the camera is perfectly still and the slides are for several "key frames" where the compression algorithm decides to replace one set of compression artifacts for another. For example try to read the first keyword under "Translates into:": https://www.youtube.com…

How precious that you think someone cares.

Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#33
post #6

I don't like to use SQL engine because I don't understand how they work, I never really know if my query will be O(1), O(log(n)), O(n), etc, or what kind of algorithm will optimize my query. Who really does understand how a SQL engine work? Don't you usually require to understand how something work before starting using it? Which SQL analyst or DB architect really knows about the internals of a SQL engine? Do they kn…

You're not scared, you're just too lazy to learn the tools of your trade. Databases are not very complex and use pretty much only textbook data structures and algorithms. Understanding how they process a given query and how a query will probably perform/scale (even without EXPLAIN ANALYZE) is not hard to learn. You do need to learn it (at some point; you don't for small data, which is most). But it's far from difficu…

>Databases are not very complex and use pretty much only textbook data structures and algorithms

skeptical expression

Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#34
post #31
post #25

I recently created a database engine (exosql [1]), only query and no storage. It uses postgres-like foreign data wrappers to get all data. It's not valid for big datasets, as it stores all in memory (or maybe it is?), but as a learning experience has been amazing to think and develop a real database: planner, executor, choose algorithms, implement features as lateral joins and so on. I will definetly listen very care…

Any books/lectures/articles you followed?

I followed specially the postgres and sqlite documentations. For some specific areas I checked their source codes. But mainly I used explain from postgres as reference on what algorithms (seq scan, hash scan and do on) use for specific queries.

Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#35

Earlier quoted context omitted.

How do you prefer to persist your data?

In memory database, dumped to file? Not saying how I would do it, just thinking alternatives. I’m using postgresql usually

Ideally, if your DB fits into RAM, it should be served from RAM entirely.

If less frequently used parts of it don't fit, offload to disk.

Ideally, the DB should guarantee data integrity after a crash even if the DB is served from RAM.

That's the ideal scenario: You have the best of all worlds.

Coincidentally, that's exactly what Postgres does.

On top of that, it's the best NoSQL database currently available.

Of course, you can use it with SQL if you ever feel the need.

Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#36
post #6

I don't like to use SQL engine because I don't understand how they work, I never really know if my query will be O(1), O(log(n)), O(n), etc, or what kind of algorithm will optimize my query. Who really does understand how a SQL engine work? Don't you usually require to understand how something work before starting using it? Which SQL analyst or DB architect really knows about the internals of a SQL engine? Do they kn…

I completely disagree.

Unless your data requirements are very specific, mem only, or not adapted to the relational paradigm any SQL engine will provide you with the best and more efficient algorithms to manipulate your data in the most common situations.

I think that if any, databases should be used more.

Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#39

Any video filter experts here? Request to any video filter expert ------------------------------------ I started watching this. The slides are unreadable but the camera is perfectly still and the slides are for several "key frames" where the compression algorithm decides to replace one set of compression artifacts for another. For example try to read the first keyword under "Translates into:": https://www.youtube.com…

How precious that you think someone cares.

I think there's an Adobe After Effects plugin. Granted the people who are set up for heavy video editing are probably a very small percentage of HN readers :) There's probably more HN readers who would take is as a challenge to do an unsupervised convolutional neural net :D and come back with a research paper. I myself don't use Adobe After Effects.

Re: How SQL Database Engines Work, by the Creator of SQLite (2008) [video]

#40
post #9

Earlier quoted context omitted.

For Postgres at least, you can literally ask it how a query works, via EXPLAIN. Now, there’s a skill to understanding the output of that, but at least it isn’t a black box.

And the query plan can literally change out from under you at any time. SQL sucks. You should be able to dictate the query plan to the engine directly. If SQL exists as a tool to create and serialize such plans via exploration and experimentation, that’s fine. As a runtime query system it is completely unsuitable.

There are some tools to force specific hints/plans on the engine depending on the database e.g. SQL Plan Management in Oracle
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