Comment by CyberRabbi
5 years ago
Over high latency links this would be virtually unusable. Why not just download the entire database into memory over XHR on page load? SQLite databases of pure data usually aren’t over 10MB in size.
5 years ago
Over high latency links this would be virtually unusable. Why not just download the entire database into memory over XHR on page load? SQLite databases of pure data usually aren’t over 10MB in size.
This particular demo page actually makes queries against an almost 700 MB large (fills one CD!) SQLite database. Because the amount of data read is almost negligible (few hundred kB), performance is limited by latency (as you say). However, high-latency links also tend to be slower, so downloading the entire database a-priori would almost always be much slower.
For example, on a 1 megabit/s link with 300 ms RTT, one example would take about 2 seconds for the data transfer itself while spending another 3 seconds or so on waiting. Downloading the entire file would take around an hour and a half.
For your 10 MB database, transferring it as a whole would take 80 seconds. Assuming this solution instead needs to read e.g. 250 kB (taking 2 seconds to transfer), it could still bounce around 250 times to the database before those 10 MB are fully downloaded. (This would be a really odd query, since it would only read on average two pages per read request)
Right but that is an artificially created demo by the author to justify the solution being presented (no offense). The question is how common are ~GB large SQLite databases in the real world relative to databases that are ~MB large?
In my experience SQLite databases of millions of rows of raw tabular data tend to compress very well into dozens of megabytes. Indeed SQLite is often touted as a file format for applications.
I'm running magnetico (https://github.com/boramalper/magnetico) on my VPS. I currently have an index of 1.6M magnet links stored in a 5GB database.
SQLite is most interesting not when the database is small, but when there are very few writes and all you do is reading. You can also look at https://datasette.io/ and see how SQLite is perfect for representing a lot of datasets and querying them
Even if you compress it, you need it in client memory which can also be a dealbreaker. Some people might need it for some projects, I know I did.
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My team has a few TB of data in SQLite files that are themselves dozens of GB each.
We're using them as a replacement for leveldb's sstables, but with the structure of full SQL. It is highly effective.
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That is hilariously wrong for a lot of use cases. I will find this very handy for some SQLite databases I have that are several GBs in size. I am looking right now at using this contribution.
It’s not hilariously wrong or wrong at all that over high latency links this would be virtually unusable.
It’s certainly possible that people are using SQLite databases with sizes on the order of gigabytes but in my experience those are the exception not the rule.
Over high latency links most anything interesting is virtually unusable, so stop using it as a high horse to stand upon.
And the article starts by mentioning that you can download the entire file if it's not too large. And then goes on to present a solution for larger files. What more answer to "Why not just download the entire database" do you expect?
I have been using SQLite databases for a few user application that has been running for close to a decade now. They are usually about 1.5GB.
BTW, SQLite has a (theoretical?) max size of 140TB! (or so I've read)
What do you think is the size of the average SQLite database?
Given their widespread uses on phones, the overall average is likely very small. KBs even.
A more relevant question might be: what would the average size of SQLite databases for web type (or even this specific use case) applications. I don't know, but 10s or 100s of MBs might not be a bad guess.
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> SQLite databases of pure data usually aren’t over 10MB in size
Why do you think this?
The demo here uses a 670MB database file.