[gdbm] - Access Violation masquerading as another Exception, needs
resport?
lazarus / 63-Database

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Gustavo 'Gus' Carreno · 2022-05-17 11:17

Hey Y'all,

I've been playing around with the GNU DBM key/value pair database.

You can find some examples on how to do it under the FPC source on the
packages/gdbm/examples folder.
As a disclaimer I haven't compiled nor ran those examples.

Nonetheless, I did copy the code, almost verbatim to my TestGNUDBM
playground project.

The issue is that on the line that retrieves the last of the keys with
gdbm_nextkey() it throws and Access Violation exception.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i try  key:=
gdbm_nextkey(FDB, key);except  on E: Exception do  begin   
memLog.Append(Format('ERROR: %s', [E.Message]));   
memLog.Append('Need to report this error triggered on the last
entry');    key:= '';  end;end;
In debug, if you continue running the program it then issues another
exception with the following text -ish:

Code: Text  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i ### Not
supported on GDB < 5.3 ###
Can the experts please tell me if this is a known issue so I don't
duplicate an issue posting?

At the moment I'm gobbling up the exception so my code doesn't
completely break, as you can see on the GitHub repo source code.
I would like not to have to do it. Even if traversing the whole
database is not the most common way to use a key/value pair store.

Cheers,
Gus

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marcov · 2022-06-17 09:11

Sounds to me as the gdbm header is outdated. There is not much use of
gdbm, so that wouldn't surprise me. Most people opt for postgres,
firebird, mysql or sqlite

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Gustavo 'Gus' Carreno · 2022-06-17 11:32

Hey Marco,

Quote from: marcov on June 17, 2022, 11:11:06 amSounds to me as the
gdbm header is outdated.

Thanks! So what should I do next?

Quote from: marcov on June 17, 2022, 11:11:06 amThere is not much use
of gdbm, so that wouldn't surprise me. Most people opt for postgres,
firebird, mysql or sqlite

I completely agree with you, but when you're messing about with pure
key/value pair databases, Free Pascal is rather lacking support on the
new kid on the block: LevelDB.

To be honest, GDBM was the only thing supported out of the box

Cheers,
Gus