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queryset-refactor: Initial pass at fixing the Oracle support. Thanks, Justin Bronn. Fixed #6161
This is untested (by me) and is a slight modification on Justin's original patch, so feedback and bug reports are welcome. git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7321 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick
parent
9ee77a7501
commit
22bb040b60
@ -25,6 +25,7 @@ IntegrityError = Database.IntegrityError
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class DatabaseFeatures(BaseDatabaseFeatures):
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allows_group_by_ordinal = False
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allows_unique_and_pk = False # Suppress UNIQUE/PK for Oracle (ORA-02259)
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empty_fetchmany_value = ()
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needs_datetime_string_cast = False
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needs_upper_for_iops = True
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supports_tablespaces = True
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@ -99,192 +100,10 @@ class DatabaseOperations(BaseDatabaseOperations):
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return 30
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def query_set_class(self, DefaultQuerySet):
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from django.db import connection
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from django.db.models.query import EmptyResultSet, GET_ITERATOR_CHUNK_SIZE, quote_only_if_word
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class OracleQuerySet(DefaultQuerySet):
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def iterator(self):
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"Performs the SELECT database lookup of this QuerySet."
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from django.db.models.query import get_cached_row
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# self._select is a dictionary, and dictionaries' key order is
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# undefined, so we convert it to a list of tuples.
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extra_select = self._select.items()
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full_query = None
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try:
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try:
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select, sql, params, full_query = self._get_sql_clause(get_full_query=True)
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except TypeError:
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select, sql, params = self._get_sql_clause()
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except EmptyResultSet:
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raise StopIteration
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if not full_query:
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full_query = "SELECT %s%s\n%s" % ((self._distinct and "DISTINCT " or ""), ', '.join(select), sql)
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cursor = connection.cursor()
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cursor.execute(full_query, params)
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fill_cache = self._select_related
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fields = self.model._meta.fields
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index_end = len(fields)
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# so here's the logic;
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# 1. retrieve each row in turn
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# 2. convert NCLOBs
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while 1:
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rows = cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)
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if not rows:
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raise StopIteration
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for row in rows:
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row = self.resolve_columns(row, fields)
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if fill_cache:
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obj, index_end = get_cached_row(klass=self.model, row=row,
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index_start=0, max_depth=self._max_related_depth)
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else:
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obj = self.model(*row[:index_end])
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for i, k in enumerate(extra_select):
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setattr(obj, k[0], row[index_end+i])
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yield obj
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def _get_sql_clause(self, get_full_query=False):
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from django.db.models.query import fill_table_cache, \
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handle_legacy_orderlist, orderfield2column
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opts = self.model._meta
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qn = connection.ops.quote_name
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# Construct the fundamental parts of the query: SELECT X FROM Y WHERE Z.
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select = ["%s.%s" % (qn(opts.db_table), qn(f.column)) for f in opts.fields]
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tables = [quote_only_if_word(t) for t in self._tables]
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joins = SortedDict()
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where = self._where[:]
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params = self._params[:]
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# Convert self._filters into SQL.
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joins2, where2, params2 = self._filters.get_sql(opts)
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joins.update(joins2)
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where.extend(where2)
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params.extend(params2)
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# Add additional tables and WHERE clauses based on select_related.
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if self._select_related:
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fill_table_cache(opts, select, tables, where, opts.db_table, [opts.db_table])
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# Add any additional SELECTs.
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if self._select:
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select.extend(['(%s) AS %s' % (quote_only_if_word(s[1]), qn(s[0])) for s in self._select.items()])
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# Start composing the body of the SQL statement.
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sql = [" FROM", qn(opts.db_table)]
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# Compose the join dictionary into SQL describing the joins.
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if joins:
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sql.append(" ".join(["%s %s %s ON %s" % (join_type, table, alias, condition)
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for (alias, (table, join_type, condition)) in joins.items()]))
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# Compose the tables clause into SQL.
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if tables:
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sql.append(", " + ", ".join(tables))
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# Compose the where clause into SQL.
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if where:
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sql.append(where and "WHERE " + " AND ".join(where))
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# ORDER BY clause
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order_by = []
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if self._order_by is not None:
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ordering_to_use = self._order_by
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else:
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ordering_to_use = opts.ordering
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for f in handle_legacy_orderlist(ordering_to_use):
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if f == '?': # Special case.
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order_by.append(DatabaseOperations().random_function_sql())
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else:
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if f.startswith('-'):
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col_name = f[1:]
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order = "DESC"
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else:
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col_name = f
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order = "ASC"
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if "." in col_name:
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table_prefix, col_name = col_name.split('.', 1)
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table_prefix = qn(table_prefix) + '.'
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else:
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# Use the database table as a column prefix if it wasn't given,
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# and if the requested column isn't a custom SELECT.
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if "." not in col_name and col_name not in (self._select or ()):
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table_prefix = qn(opts.db_table) + '.'
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else:
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table_prefix = ''
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order_by.append('%s%s %s' % (table_prefix, qn(orderfield2column(col_name, opts)), order))
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if order_by:
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sql.append("ORDER BY " + ", ".join(order_by))
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# Look for column name collisions in the select elements
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# and fix them with an AS alias. This allows us to do a
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# SELECT * later in the paging query.
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cols = [clause.split('.')[-1] for clause in select]
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for index, col in enumerate(cols):
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if cols.count(col) > 1:
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col = '%s%d' % (col.replace('"', ''), index)
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cols[index] = col
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select[index] = '%s AS %s' % (select[index], col)
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# LIMIT and OFFSET clauses
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# To support limits and offsets, Oracle requires some funky rewriting of an otherwise normal looking query.
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select_clause = ",".join(select)
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distinct = (self._distinct and "DISTINCT " or "")
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if order_by:
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order_by_clause = " OVER (ORDER BY %s )" % (", ".join(order_by))
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else:
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#Oracle's row_number() function always requires an order-by clause.
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#So we need to define a default order-by, since none was provided.
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order_by_clause = " OVER (ORDER BY %s.%s)" % \
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(qn(opts.db_table), qn(opts.fields[0].db_column or opts.fields[0].column))
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# limit_and_offset_clause
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if self._limit is None:
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assert self._offset is None, "'offset' is not allowed without 'limit'"
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if self._offset is not None:
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offset = int(self._offset)
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else:
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offset = 0
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if self._limit is not None:
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limit = int(self._limit)
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else:
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limit = None
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limit_and_offset_clause = ''
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if limit is not None:
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limit_and_offset_clause = "WHERE rn > %s AND rn <= %s" % (offset, limit+offset)
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elif offset:
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limit_and_offset_clause = "WHERE rn > %s" % (offset)
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if len(limit_and_offset_clause) > 0:
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fmt = \
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"""SELECT * FROM
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(SELECT %s%s,
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ROW_NUMBER()%s AS rn
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%s)
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%s"""
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full_query = fmt % (distinct, select_clause,
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order_by_clause, ' '.join(sql).strip(),
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limit_and_offset_clause)
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else:
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full_query = None
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if get_full_query:
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return select, " ".join(sql), params, full_query
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else:
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return select, " ".join(sql), params
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# Getting the base default `Query` object.
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DefaultQuery = DefaultQuerySet().query.__class__
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class OracleQuery(DefaultQuery):
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def resolve_columns(self, row, fields=()):
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from django.db.models.fields import DateField, DateTimeField, \
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TimeField, BooleanField, NullBooleanField, DecimalField, Field
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@ -331,6 +150,66 @@ class DatabaseOperations(BaseDatabaseOperations):
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values.append(value)
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return values
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def as_sql(self, with_limits=True):
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"""
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Creates the SQL for this query. Returns the SQL string and list
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of parameters. This is overriden from the original Query class
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to accommodate Oracle's limit/offset SQL.
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If 'with_limits' is False, any limit/offset information is not
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included in the query.
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"""
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# The `do_offset` flag indicates whether we need to construct
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# the SQL needed to use limit/offset w/Oracle.
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do_offset = with_limits and (self.high_mark or self.low_mark)
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# If no offsets, just return the result of the base class
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# `as_sql`.
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if not do_offset:
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return super(OracleQuery, self).as_sql(with_limits=False)
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# `get_columns` needs to be called before `get_ordering` to
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# populate `_select_alias`.
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self.pre_sql_setup()
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out_cols = self.get_columns()
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ordering = self.get_ordering()
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# Getting the "ORDER BY" SQL for the ROW_NUMBER() result.
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if ordering:
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rn_orderby = ', '.join(ordering)
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else:
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# Oracle's ROW_NUMBER() function always requires an
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# order-by clause. So we need to define a default
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# order-by, since none was provided.
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qn = self.quote_name_unless_alias
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opts = self.model._meta
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rn_orderby = '%s.%s' % (qn(opts.db_table), qn(opts.fields[0].db_column or opts.fields[0].column))
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# Getting the selection SQL and the params, which has the `rn`
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# extra selection SQL; we pop `rn` after this completes so we do
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# not get the attribute on the returned models.
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self.extra_select['rn'] = 'ROW_NUMBER() OVER (ORDER BY %s )' % rn_orderby
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sql, params= super(OracleQuery, self).as_sql(with_limits=False)
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self.extra_select.pop('rn')
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# Constructing the result SQL, using the initial select SQL
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# obtained above.
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result = ['SELECT * FROM (%s)' % sql]
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# Place WHERE condition on `rn` for the desired range.
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result.append('WHERE rn > %d' % self.low_mark)
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if self.high_mark:
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result.append('AND rn <= %d' % self.high_mark)
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# Returning the SQL w/params.
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return ' '.join(result), params
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from django.db import connection
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class OracleQuerySet(DefaultQuerySet):
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"The OracleQuerySet is overriden to use OracleQuery."
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def __init__(self, model=None, query=None):
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super(OracleQuerySet, self).__init__(model=model, query=query)
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self.query = query or OracleQuery(self.model, connection)
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return OracleQuerySet
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def quote_name(self, name):
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