[GRASS-dev] SQLite driver now with transactions

[Markus Neteler]

Hi,

thanks to Antonio Galea, we now have SQL transactions
in the SQLite driver which speeds up "execute" for
large attribute tables:

### EXECUTE, SQLite driver

# TEST 1: geodetic_pts, 13 columns, points=29939

# without transactions, points map
time g.copy vect=geodetic_pts,ggg
real    0m8.076s
user    0m4.135s
sys     0m5.182s

# with transactions, points map
time g.copy vect=geodetic_pts,ggg2
real    0m7.789s
user    0m4.192s
sys     0m5.424s

#####
# TEST 2: streets_wake, 35 columns, lines=49746

# without transactions, lines map
time g.copy vect=streets_wake,ggg2
real    0m22.692s
user    0m11.685s
sys     0m15.315s

# with transactions, lines map
time g.copy vect=geodetic_pts,ggg2
real    0m7.663s
user    0m4.101s
sys     0m4.327s

#####
# TEST 3, soils_wake, 7 columns, areas=47156

# without transactions, area map
time g.copy vect=soils_wake,ggg2
real    0m9.856s
user    0m4.940s
sys     0m5.837s

# with transactions, area map
time g.copy vect=soils_wake,ggg2
real    0m10.208s
user    0m4.986s
sys     0m6.319s


The improvement is (naturally) significant when you have
(a) large attribute table(s) attached to the vector map.

Markus