def compute_counts(db, tabname, force=False):
if not force:
# Use the saved count from previous snapshot, and
# just add the rows added by this one
assert db.in_transaction()
# Load the count that was valid before this transaction
db2 = DB(':'.join(db.path))
try:
nrows = db2.table(tabname).nrows()
new = False
except IOError:
# This is a new table
nrows = 0
new = True
# Fetch all cells modified by this transaction
cells = db.table(tabname).get_cells_in_snapshot(db.snapid)
if not new:
# Count up rows before modification
nrows_old = compute_counts_aux(
db2, tabname, cells, progress_callback=pool2.progress_pct_nnl)
else:
nrows_old = 0
# Count up rows in modified cells
nrows_new = compute_counts_aux(db, tabname, cells)
# The new row count
nrows += nrows_new - nrows_old
else:
# Directly count everything
cells = db.table(tabname).get_cells()
nrows = compute_counts_aux(db, tabname, cells)
return nrows
# Return it as a ColGroup(), keyed to this static cell_id
yield static_cell, ColGroup([(key, keys), (oval, vals)])
def _accumulate_and_write(qresult, qwriter, key, val, oval):
for static_cell, rows in _accumulator(qresult, key, val, oval):
result = qwriter.write(static_cell, rows)
yield result
# yield 0, [1, 2]
if __name__ == '__main__':
from join_ops import DB
ntot = 0
db = DB('db2')
writer = IntoWriter(db, "magbase WHERE obj_id |= obj_id")
for band in 'grizy':
# for band in 'g':
nband = 0
q = db.query(
"obj_id, ap_mag, filterid FROM obj, det WHERE filterid == '%s.0000'"
% band)
for static_cell, rows in q.execute(
[(_accumulate_and_write, writer, 'obj_id', 'ap_mag', band)],
group_by_static_cell=True):
nband += len(rows)
## q = db.query("obj_id, ap_mag, filterid FROM obj, det WHERE filterid == 'y.0000' INTO magbase")
## for static_cell, rows in q.execute([(_accumulator, 'obj_id', 'ap_mag', 'ap_mag')], group_by_static_cell=True):
## nband += len(rows)
ntot += nband
