3 ms·

Since it’s not clear from the title: embedded here does not mean sqlite-inside-your-app but small devices with microcontrollers

hgyjnbdet 2y ago
That's what I initially thought too, though having read and understood little of the article, is sqlite not a consideration too? Or does it take up too much memory?
- vitaminCPP 2y ago
  SQLite would require a file system. Embedded systems typically do not have this.
  - ComputerGuru 2y ago
    SQLite doesn’t require a file system per se, as you can create an in-memory db and then use vfs to load/write the actual data from/to your IO layer.
  - interroboink 2y ago
    Though note you can define your own "Virtual File System" (VFS) for SQLite to use[1]. It might be a bit of an undertaking, but I think you could use that to run on just about anything with storage you control. (I haven't done it myself, just some research back in the day) [1] https://www.sqlite.org/c3ref/vfs_find.html https://www.sqlite.org/c3ref/vfs_find.html
- tyingq 2y ago
  There's a pretty good write up on running sqlite on an STM32 here: https://github.com/luismeruje/SQLite-STM32 https://github.com/luismeruje/SQLite-STM32 Keeping in mind that STM32 is on the high end of what you might call embedded, and the writeup is pretty clear that it barely fits/works there, lots of caveats, etc.
- g15jv2dp 2y ago
  Another thing to consider is that sqlite dynamically allocates memory. You typically want to avoid that in embedded. Everything is slow, memory is scarce. The sheer code size is also a issue.
  - FredFS456 2y ago
    Sqlite has a mode where you can give it an area of memory and it will never use any other memory.
    - g15jv2dp 2y ago
      It's still going to dynamically allocate its memory in there, isn't it? This is a slow operation.
      - jmole 2y ago
        Memory allocation isn’t that slow (in fact all the ram is SRAM which is typically quite fast), it’s just that you only have 256k-1M RAM in total. This means that any time you’re saving later by trying to fill space now ends up getting wasted when that memory needs to be reclaimed.

hgyjnbdet 2y ago

That's what I initially thought too, though having read and understood little of the article, is sqlite not a consideration too? Or does it take up too much memory?

vitaminCPP 2y ago
SQLite would require a file system. Embedded systems typically do not have this.
- ComputerGuru 2y ago
  SQLite doesn’t require a file system per se, as you can create an in-memory db and then use vfs to load/write the actual data from/to your IO layer.
- interroboink 2y ago
  Though note you can define your own "Virtual File System" (VFS) for SQLite to use[1]. It might be a bit of an undertaking, but I think you could use that to run on just about anything with storage you control. (I haven't done it myself, just some research back in the day) [1] https://www.sqlite.org/c3ref/vfs_find.html https://www.sqlite.org/c3ref/vfs_find.html
tyingq 2y ago
There's a pretty good write up on running sqlite on an STM32 here: https://github.com/luismeruje/SQLite-STM32 https://github.com/luismeruje/SQLite-STM32 Keeping in mind that STM32 is on the high end of what you might call embedded, and the writeup is pretty clear that it barely fits/works there, lots of caveats, etc.
g15jv2dp 2y ago
Another thing to consider is that sqlite dynamically allocates memory. You typically want to avoid that in embedded. Everything is slow, memory is scarce. The sheer code size is also a issue.
- FredFS456 2y ago
  Sqlite has a mode where you can give it an area of memory and it will never use any other memory.
  - g15jv2dp 2y ago
    It's still going to dynamically allocate its memory in there, isn't it? This is a slow operation.
    - jmole 2y ago
      Memory allocation isn’t that slow (in fact all the ram is SRAM which is typically quite fast), it’s just that you only have 256k-1M RAM in total. This means that any time you’re saving later by trying to fill space now ends up getting wasted when that memory needs to be reclaimed.