locking dba files, how to in details

[fabioheller]

Hi all!
I'have read here in this forum that dba files should be always locked as soon as they are open, but I have tried this experiment and I cannot say they are locked for sure, can anybody tell me what's wrong please?

Experiment:

• Thread n.1 opens file "myfile.db"
• sleep 10 seconds
• try to read "mykey" (value should be "Good morning")

---

• While first thread is sleeping another thread opens "myfile.db"

• replaces "mykey" with value "Good evening"

---

Result of first thread reding? "mykey"="Good evenong"

What's wrong?

[Anon]

Is Insert and replace atomic by chanche?
So we don't need to block the entire file?