Re: [mv] File Locking [tag export database]

[mikeh@minivend.com]

Quoting Handytman@aol.com (Handytman@aol.com):
> 
> Question: Do [tag export database] and [tag flag write] 'lock' the file 
> before operating upon it?

Of course.

> 
> Reason For Asking: I am trying to track inventory with MiniVend. The code on 
> the 'report.html' page appears to update the 'qty' field in 'inventory.gdbm' 
> but not the corresponding field in 'inventory.asc.' However, I want my client 
> to be able to look at 'inventory.asc' and see up-to-date numbers. So...
> I could add [tag export inventory inventory.asc][/tag] to the report.html 
> page. That (if I understand correctly) would rewrite 'inventory.asc' every 
> time an order is placed, with updated quantities. The only fear I have is of 
> near-simultaneous orders getting garbled data from an unlocked, open file.
> 
> Then again, if I can safely rewrite 'inventory.asc' from the receipt page, 
> why not just add a quantity field to 'products.asc' and rewrite *this* file 
> with each order....Hmmm :o)

Don't use the products table. That would hold off all catalog accesses
while the write was in effect. Use a small outboard table.

SQL is best for this kind of stuff, though. While you can do some 
read-write operations with MiniVend DBM databases, it won't scale to
busy (hundred thousand hits per day or more) catalogs.

-- 
Mike Heins                          http://www.minivend.com/  ___ 
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