3 ms·

Also worth noting that Sqlite released a WAL2 journal mode recently that eliminates the "stop of the world" we had with WAL when checkpointing. Basically it mai

by Sytten 4y ago

Also worth noting that Sqlite released a WAL2 journal mode recently that eliminates the "stop of the world" we had with WAL when checkpointing. Basically it maintains two wal files and switched between them when one needs to be checkpointed. It is quite neat!

simonw 4y ago
WAL2 mode is still only available in a branch - I've been hoping they'll merge it to main at some point, but I've not been following things closely enough to know if there are reasons that they wouldn't eventually do that. https://www.sqlite.org/cgi/src/doc/wal2/doc/wal2.md https://www.sqlite.org/cgi/src/doc/wal2/doc/wal2.md
- alberth 4y ago
  Not only WAL2, but there is yet another branch with BEGIN CONCURRENT which also helps with scaling concurrency. https://www.sqlite.org/cgi/src/doc/begin-concurrent/doc/begin_concurrent.md https://www.sqlite.org/cgi/src/doc/begin-concurrent/doc/begi... I really hope these two branches get merged into the mainline sometime soon. I'm not sure what's the blocker, since both branches have existed for literally years and are refreshed frequently. WAL2 + BEGIN CONCURRENT would solve probably 99.9% of developer scaling needs.
  - chasil 4y ago
    SQLite runs critical systems on the A350 in flight. Stability is vastly more important than new functionality in that context.
    - thatwasunusual 4y ago
      > SQLite runs critical systems on the A350 in flight. Can you document that? I was under the impression that they used SQLite for on ground simulations?
      - chasil 4y ago
        Since the DO-178B certification was obtained by SQLite, it may be used in critical avionics components. Rockwell-Collins is the organization that prompted Dr. Hipp to obtain DO-178B. I actually worked at Rockwell-Collins in the early 90s. I do generally prefer airlines flying Airbus, BTW. "Airbus confirms that SQLite is being used in the flight software for the A350 XWB family of aircraft." https://www.sqlite.org/famous.html https://www.sqlite.org/famous.html
ignoramous 4y ago
> Basically it maintains two wal files and switched between them when one needs to be checkpointed. It is quite neat! See also: eglSwapBuffers, https://katatunix.wordpress.com/2014/09/17/lets-talk-about-eglmakecurrent-eglswapbuffers-glflush-glfinish/ https://katatunix.wordpress.com/2014/09/17/lets-talk-about-e...

by Sytten 4y ago

simonw 4y ago

WAL2 mode is still only available in a branch - I've been hoping they'll merge it to main at some point, but I've not been following things closely enough to know if there are reasons that they wouldn't eventually do that. https://www.sqlite.org/cgi/src/doc/wal2/doc/wal2.md https://www.sqlite.org/cgi/src/doc/wal2/doc/wal2.md

alberth 4y ago
Not only WAL2, but there is yet another branch with BEGIN CONCURRENT which also helps with scaling concurrency. https://www.sqlite.org/cgi/src/doc/begin-concurrent/doc/begin_concurrent.md https://www.sqlite.org/cgi/src/doc/begin-concurrent/doc/begi... I really hope these two branches get merged into the mainline sometime soon. I'm not sure what's the blocker, since both branches have existed for literally years and are refreshed frequently. WAL2 + BEGIN CONCURRENT would solve probably 99.9% of developer scaling needs.
- chasil 4y ago
  SQLite runs critical systems on the A350 in flight. Stability is vastly more important than new functionality in that context.
  - thatwasunusual 4y ago
    > SQLite runs critical systems on the A350 in flight. Can you document that? I was under the impression that they used SQLite for on ground simulations?
    - chasil 4y ago
      Since the DO-178B certification was obtained by SQLite, it may be used in critical avionics components. Rockwell-Collins is the organization that prompted Dr. Hipp to obtain DO-178B. I actually worked at Rockwell-Collins in the early 90s. I do generally prefer airlines flying Airbus, BTW. "Airbus confirms that SQLite is being used in the flight software for the A350 XWB family of aircraft." https://www.sqlite.org/famous.html https://www.sqlite.org/famous.html

ignoramous 4y ago

> Basically it maintains two wal files and switched between them when one needs to be checkpointed. It is quite neat! See also: eglSwapBuffers, https://katatunix.wordpress.com/2014/09/17/lets-talk-about-eglmakecurrent-eglswapbuffers-glflush-glfinish/ https://katatunix.wordpress.com/2014/09/17/lets-talk-about-e...