def get(self, request, *args, **kwargs):
codes = set()
try:
num = int(request.GET.get('num', '5'))
except ValueError: # NOQA
return HttpResponseBadRequest()
prefix = request.GET.get('prefix')
batch_size = 500
if 'postgres' in settings.DATABASES['default']['ENGINE']:
batch_size = 5_000
"""
We're trying to check if any of the requested codes already exists in the database. Generally, this is a
SELECT code FROM voucher WHERE code IN (…)
query. However, it turns out that this query get's rather slow if an organizer has lots of vouchers, even
with a organizer with just over 50_000 vouchers, we've seen that creating 20_000 new voucher codes took
just over 30 seconds. There's another way of doing this query on PostgreSQL, which is joining with a
temporary table
SELECT code FROM voucher INNER JOIN (VALUES …) vals(v) ON (code = v)
This is significantly faster, inserting 20_000 vouchers now takes 2-3s instead of 31s on the same dataset.
It's still slow, and removing the JOIN to the event table doesn't significantly speed it up. We might need
an entirely different approach at some point.
"""
while len(codes) < num:
new_codes = set()
for i in range(
min(num - len(codes), batch_size
)): # Work around SQLite's SQLITE_MAX_VARIABLE_NUMBER
new_codes.add(_generate_random_code(prefix=prefix))
if 'postgres' in settings.DATABASES['default']['ENGINE']:
with connection.cursor() as cursor:
args = list(new_codes) + [request.organizer.pk]
tmptable = "VALUES " + (", ".join(
['(%s)'] * len(new_codes)))
cursor.execute(
f'SELECT code '
f'FROM "{Voucher._meta.db_table}" '
f'INNER JOIN ({tmptable}) vals(v) ON ("{Voucher._meta.db_table}"."code" = "v")'
f'INNER JOIN "{Event._meta.db_table}" ON ("{Voucher._meta.db_table}"."event_id" = "{Event._meta.db_table}"."id") '
f'WHERE "{Event._meta.db_table}"."organizer_id" = %s',
args)
for row in cursor.fetchall():
new_codes.remove(row[0])
else:
new_codes -= set([
v['code'] for v in Voucher.objects.filter(
code__in=new_codes).values('code')
])
codes |= new_codes
return JsonResponse({'codes': list(codes)})
def get(self, request, *args, **kwargs):
codes = set()
try:
num = int(request.GET.get('num', '5'))
except ValueError: # NOQA
return HttpResponseBadRequest()
while len(codes) < num:
new_codes = set()
for i in range(min(num - len(codes), 500)): # Work around SQLite's SQLITE_MAX_VARIABLE_NUMBER
new_codes.add(_generate_random_code())
new_codes -= set([v['code'] for v in Voucher.objects.filter(code__in=new_codes).values('code')])
codes |= new_codes
return JsonResponse({
'codes': list(codes)
})
def get(self, request, *args, **kwargs):
codes = set()
try:
num = int(request.GET.get('num', '5'))
except ValueError: # NOQA
return HttpResponseBadRequest()
while len(codes) < num:
new_codes = set()
for i in range(min(num - len(codes), 500)): # Work around SQLite's SQLITE_MAX_VARIABLE_NUMBER
new_codes.add(_generate_random_code())
new_codes -= set([v['code'] for v in Voucher.objects.filter(code__in=new_codes).values('code')])
codes |= new_codes
return JsonResponse({
'codes': list(codes)
})
