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Has anyone knwoledge to share about tied hashes as database backend in
cgi-scripts?

I'm running a CGI that will acess a DBM file (DB_File) as a tied hash
like this:

sub pseudo-code{
tie %hash
read(!) something
untied %hash
}

Do I have to use a file lock algorithm wrapped around when I am just
goint to READ from the file?

Will file corruption over time be a problem? (the script will be
running on a heavy load website, multiple processes, maybe sometimes
to read all at once)

As I udnerstand it I'll have to lock the DB_File only for
write/read-write access, but for reading only??

(Dan) wrote:
> Do I have to use a file lock algorithm wrapped around when I am just
> goint to READ from the file?
>
> Will file corruption over time be a problem? (the script will be
> running on a heavy load website, multiple processes, maybe sometimes
> to read all at once)
>
> As I udnerstand it I'll have to lock the DB_File only for
> write/read-write access, but for reading only??

[this applies much more generally than tied hashes]

If anyone is going to be writing, then *everyone* has to lock. Readers
lock with LOCK_SH, writers with LOCK_EX. See the documentation for
DB_File for some important caveats when locking. If you have control
of every program accessing this database, it is probably a better idea
to use a lockfile: lock the file before you tie, and untie before you
unlock.

Ben

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