Nothing to see here. (The syntax I used doesn't have the semantics I expected it to have.)
Daniel Shahaf wrote on Thu, Jul 14, 2011 at 05:53:52 +0300: > From my shell session: > > [[[ > % time sqlite3 foo.db "SELECT hash, revision, offset, size, expanded_size > FROM rep_cache;" > /dev/null > sqlite3 foo.db > /dev/null 12.72s user 0.69s system 98% cpu 13.575 total > > % time sqlite3 foo.db "SELECT hash, revision, offset, size, expanded_size > FROM rep_cache;" > /dev/null > sqlite3 foo.db > /dev/null 12.56s user 0.94s system 99% cpu 13.561 total > > % time sqlite3 foo.db "SELECT hash, revision, offset, size, expanded_size, > COUNT(*) FROM rep_cache;" > /dev/null > sqlite3 foo.db > /dev/null 2.76s user 0.72s system 99% cpu 3.492 total > > % time sqlite3 foo.db "SELECT hash, revision, offset, size, expanded_size, > COUNT(*) FROM rep_cache;" > /dev/null > sqlite3 foo.db > /dev/null 2.79s user 0.69s system 99% cpu 3.498 total > > % time sqlite3 foo.db "SELECT hash, revision, offset, size, expanded_size > FROM rep_cache;" > /dev/null > sqlite3 foo.db > /dev/null 12.62s user 0.75s system 99% cpu 13.430 total > > % sqlite3 -version > 3.7.4 > ]]] > > That is: adding COUNT(*) to the query makes it 3.9 times faster. > > Huh? How does that make sense? Should we do anything differently in > our code in light of this? > > > [ This isn't a fabricated example --- this is the query I added to > rep-cache.c today ]
