-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 07/19/2010 07:50 AM, Sam Carleton wrote: > How expensive is doing a PRAGMA database_list?
17. Without context numbers are useless. The internal implementation involves traversing data structures and populating the VDBE so that you get the right answer, so it is mostly changing representation of data from one format to another. > Is this very expensive? Relative to network and disk i/o, no. > Normal load is 5 to 50 clients all hitting the server every 1 to 5 seconds. > One hit could be multiple requests. That is a trivial load for any machine of the last 10 years. You could easily add in some prime calculation or password brute forcing without breaking a sweat. In any event by far the best thing to do is get it right and testable first, which generally means the simplest code possible, and then worry about optimisation. That way you'll have a baseline and test code to see if your optimization broke anything. Something implied by your approach to this problem is that you can't hook into the config change system which is what would seem most logical. Another approach which may work for you is to use the filename as the attached database name: sqlite> attach "/home/rogerb/xx" as "/home/rogerb/xx"; sqlite> create table "/home/rogerb/xx".foo(x,y,z); If the filename has " in it then quote using [ and ]. You'll obviously need an error handler that catches SQLITE_ERROR on the first query and attaches the missing database. This approach will work if different attached databases are needed on the same connection for different queries and saves you the hassle of constantly checking that "eventdb" is bound to the correct one. Roger -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkxEswQACgkQmOOfHg372QQRiQCfeQnRwSScFzdPmCPcjmPr9zWS UpIAoN3PKaxQGRYDRkEYUMVJxZF38es3 =wvfZ -----END PGP SIGNATURE----- _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
