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Fixed Oracle backend limit/offset SQL to again use extra_select, properly this time. This cleans up a test case failure, and hopefully gets contrib.gis working again. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8471 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Matt Boersma 2008-08-22 20:26:20 +00:00
parent 1b8b9686fa
commit 6e36ce1429
1 changed files with 37 additions and 28 deletions
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63
django/db/backends/oracle/query.py
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@ -82,55 +82,64 @@ def query_class(QueryClass, Database):
"""
Creates the SQL for this query. Returns the SQL string and list
of parameters. This is overriden from the original Query class
to accommodate Oracle's limit/offset SQL.
to handle the additional SQL Oracle requires to emulate LIMIT
and OFFSET.
If 'with_limits' is False, any limit/offset information is not
included in the query.
"""
# The `do_offset` flag indicates whether we need to construct
# the SQL needed to use limit/offset w/Oracle.
# the SQL needed to use limit/offset with Oracle.
do_offset = with_limits and (self.high_mark is not None
or self.low_mark)
if not do_offset:
sql, params = super(OracleQuery, self).as_sql(with_limits=False,
with_col_aliases=with_col_aliases or do_offset)
if do_offset:
# Get the "ORDER BY" SQL for the ROW_NUMBER() result.
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:
# Oracle's ROW_NUMBER() function always requires an
# order-by clause. So we need to define a default
# order-by, since none was provided.
# 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))
# Collect all the selected column names or aliases.
outer_cols = []
for col in self.get_columns(True):
if ' AS ' in col:
outer_cols.append(col.split(' AS ', 1)[1])
else:
outer_cols.append(col.rsplit('.', 1)[1])
# 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)
# Rewrite the original SQL query to select ROW_NUMBER() and involve
# it in the WHERE clause, then wrap everything in an outer SELECT
# statement that omits the "rn" column. This is the canonical way
# to emulate LIMIT and OFFSET on Oracle.
sql = 'SELECT ROW_NUMBER() OVER (ORDER BY %s) rn, %s' % (rn_orderby, sql[7:])
result = ['SELECT %s FROM (%s)' % (', '.join(outer_cols), sql)]
# Place WHERE condition on `rn` for the desired range.
result.append('WHERE rn > %d' % self.low_mark)
# 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)
if self.high_mark is not None:
result.append('AND rn <= %d' % self.high_mark)
sql = ' '.join(result)
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