说明
resource
sqlite_popen ( string filename [, int mode [, string &error_message]] )
This function behaves identically to sqlite_open()
except that is uses the persistent resource mechanism of PHP.
For information about the meaning of the parameters, read the
sqlite_open() manual page.
sqlite_popen() will first check to see if a persistent
handle has already been opened for the given
filename. If it finds one, it returns that handle
to your script, otherwise it opens a fresh handle to the database.
The benefit of this approach is that you don't incur the performance
cost of re-reading the database and index schema on each page hit served
by persistent web server SAPI's (any SAPI except for regular CGI or CLI).
注:
If you use persistent handles and have the database updated by a
background process (perhaps via a crontab), and that process re-creates
the database by overwriting it (either by unlinking and rebuilding, or
moving the updated version to replace the current version),
you may experience undefined behaviour when a persistent handle on the
old version of the database is recycled.
To avoid this situation, have your background processes open the same
database file and perform their updates in a transaction.
sqlite_open