-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Robert Citek wrote: >> A considerable amount of time in your test script is actually spent in print >> calls to pipes. > > I don't follow. An unordered query takes 3 seconds while an ordered > query takes 99 seconds. Are you saying the sorting process is > printing to pipes behind the scenes?
Your script does that for each output (piping the lines into wc -l). This introduces noise into your results since filling the pipe causes the sender to block. The SQLite shell is also having to format each line - something sort does not do. Obviously the order of magnitude time differences mean the sort internals are still different enough. You can use the explain command to see what SQLite is doing behind the scenes. Use ".explain on" followed by "explain select ...." - ie prefix your query with "explain". You can see that without an index the data is all copied to a temporary table that is then sorted as an example. You can make the temp tables be memory based rather than disk based with a pragma. http://www.sqlite.org/opcode.html Roger -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAksthbwACgkQmOOfHg372QTYxQCg4aaQ+UCzcI9LJwhov54xdPKg +BgAoMh7x9GwzPTm/bHNi5k9Dye8IUUl =Y3jz -----END PGP SIGNATURE----- _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
