On 10/20/2012 09:14 PM, Simon Slavin wrote:
On 19 Oct 2012, at 9:40pm, Efim Dyadkin<efim.dyad...@pdgm.com>
wrote:
You are right about the purpose of unlink but it is out of context.
There are a transaction in progress and hot journal on disk. If
journal can't be deleted by the end of transaction, the transaction
can't be considered to be successfully finished.
This is not correct. SQLite does not close the journal file at the
end of every transaction unless you have only a single connection to
the database and the journal mode set to DELETE, and that is not
common these days because creating and deleting files is so slow.
The times you should see a journal file deleted is when all
connections to the database have been closed: you've done a _close()
for every _open().
In WAL mode, the WAL file is held open by a connection until it
is closed. And only deleted after the number of connections to the
database drops to zero (the last connection usually unlinks it as
part of the sqlite3_close() call).
If you're running with journal_mode=DELETE (the default), the journal
file is always closed and unlinked at the end of each write
transaction.
If using journal_mode=TRUNCATE or journal_mode=PERSIST on unix, then
the journal file is always closed at the end of a write transaction.
However, on win32 (or any other system where it is impossible to
delete a file while the current or some other process has it open),
the journal file file descriptor may be held open between transactions.
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