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Fixed .distinct() not working with slicing in Oracle, due to the 

row numbers necessarily being distinct.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@9221 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Ian Kelly 2008-10-10 17:15:58 +00:00
parent 227a5a4ee6
commit 9a72913edd
2 changed files with 17 additions and 35 deletions
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46
django/db/backends/oracle/query.py
View File

@ -26,8 +26,16 @@ def query_class(QueryClass, Database):
class OracleQuery(QueryClass):
def resolve_columns(self, row, fields=()):
index_start = len(self.extra_select.keys())
values = [self.convert_values(v, None) for v in row[:index_start]]
# If this query has limit/offset information, then we expect the
# first column to be an extra "_RN" column that we need to throw
# away.
if self.high_mark is not None or self.low_mark:
rn_offset = 1
else:
rn_offset = 0
index_start = rn_offset + len(self.extra_select.keys())
values = [self.convert_values(v, None)
for v in row[rn_offset:index_start]]
for value, field in map(None, row[index_start:], fields):
values.append(self.convert_values(value, field))
return values
@ -97,49 +105,17 @@ def query_class(QueryClass, Database):
sql, params = super(OracleQuery, self).as_sql(with_limits=False,
with_col_aliases=with_col_aliases)
else:
# `get_columns` needs to be called before `get_ordering` to
# populate `_select_alias`.
self.pre_sql_setup()
self.get_columns()
ordering = self.get_ordering()
# Oracle's ROW_NUMBER() function requires an ORDER BY clause.
if ordering:
rn_orderby = ', '.join(ordering)
else:
# Create a default ORDER BY since none was specified.
qn = self.quote_name_unless_alias
opts = self.model._meta
rn_orderby = '%s.%s' % (qn(opts.db_table),
qn(opts.fields[0].db_column or opts.fields[0].column))
# Ensure the base query SELECTs our special "_RN" column
self.extra_select['_RN'] = ('ROW_NUMBER() OVER (ORDER BY %s)'
% rn_orderby, '')
sql, params = super(OracleQuery, self).as_sql(with_limits=False,
with_col_aliases=True)
# Wrap the base query in an outer SELECT * with boundaries on
# the "_RN" column. This is the canonical way to emulate LIMIT
# and OFFSET on Oracle.
sql = 'SELECT * FROM (%s) WHERE "_RN" > %d' % (sql, self.low_mark)
sql = 'SELECT * FROM (SELECT ROW_NUMBER() OVER (ORDER BY 1) AS "_RN", "_SUB".* FROM (%s) "_SUB") WHERE "_RN" > %d' % (sql, self.low_mark)
if self.high_mark is not None:
sql = '%s AND "_RN" <= %d' % (sql, self.high_mark)
return sql, params
def set_limits(self, low=None, high=None):
super(OracleQuery, self).set_limits(low, high)
# We need to select the row number for the LIMIT/OFFSET sql.
# A placeholder is added to extra_select now, because as_sql is
# too late to be modifying extra_select. However, the actual sql
# depends on the ordering, so that is generated in as_sql.
self.extra_select['_RN'] = ('1', '')
def clear_limits(self):
super(OracleQuery, self).clear_limits()
if '_RN' in self.extra_select:
del self.extra_select['_RN']
_classes[QueryClass] = OracleQuery
return OracleQuery

6
tests/regressiontests/queries/models.py
View File

@ -334,6 +334,12 @@ Bug #4464
>>> Item.objects.filter(tags__in=[t1, t2]).filter(tags=t3)
[<Item: two>]
Make sure .distinct() works with slicing (this was broken in Oracle).
>>> Item.objects.filter(tags__in=[t1, t2]).order_by('name')[:3]
[<Item: one>, <Item: one>, <Item: two>]
>>> Item.objects.filter(tags__in=[t1, t2]).distinct().order_by('name')[:3]
[<Item: one>, <Item: two>]
Bug #2080, #3592
>>> Author.objects.filter(item__name='one') | Author.objects.filter(name='a3')
[<Author: a1>, <Author: a3>]