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Diffstat (limited to 'lib/sqlalchemy/engine/result.py')
| -rw-r--r-- | lib/sqlalchemy/engine/result.py | 998 |
1 files changed, 998 insertions, 0 deletions
diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py new file mode 100644 index 000000000..91d161348 --- /dev/null +++ b/lib/sqlalchemy/engine/result.py @@ -0,0 +1,998 @@ +# engine/result.py +# Copyright (C) 2005-2012 the SQLAlchemy authors and contributors <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: http://www.opensource.org/licenses/mit-license.php + +"""Define result set constructs including :class:`.ResultProxy` +and :class:`.RowProxy.""" + + +from itertools import izip +from .. import exc, types, util +from ..sql import expression +import collections + +# This reconstructor is necessary so that pickles with the C extension or +# without use the same Binary format. +try: + # We need a different reconstructor on the C extension so that we can + # add extra checks that fields have correctly been initialized by + # __setstate__. + from sqlalchemy.cresultproxy import safe_rowproxy_reconstructor + + # The extra function embedding is needed so that the + # reconstructor function has the same signature whether or not + # the extension is present. + def rowproxy_reconstructor(cls, state): + return safe_rowproxy_reconstructor(cls, state) +except ImportError: + def rowproxy_reconstructor(cls, state): + obj = cls.__new__(cls) + obj.__setstate__(state) + return obj + +try: + from sqlalchemy.cresultproxy import BaseRowProxy +except ImportError: + class BaseRowProxy(object): + __slots__ = ('_parent', '_row', '_processors', '_keymap') + + def __init__(self, parent, row, processors, keymap): + """RowProxy objects are constructed by ResultProxy objects.""" + + self._parent = parent + self._row = row + self._processors = processors + self._keymap = keymap + + def __reduce__(self): + return (rowproxy_reconstructor, + (self.__class__, self.__getstate__())) + + def values(self): + """Return the values represented by this RowProxy as a list.""" + return list(self) + + def __iter__(self): + for processor, value in izip(self._processors, self._row): + if processor is None: + yield value + else: + yield processor(value) + + def __len__(self): + return len(self._row) + + def __getitem__(self, key): + try: + processor, obj, index = self._keymap[key] + except KeyError: + processor, obj, index = self._parent._key_fallback(key) + except TypeError: + if isinstance(key, slice): + l = [] + for processor, value in izip(self._processors[key], + self._row[key]): + if processor is None: + l.append(value) + else: + l.append(processor(value)) + return tuple(l) + else: + raise + if index is None: + raise exc.InvalidRequestError( + "Ambiguous column name '%s' in result set! " + "try 'use_labels' option on select statement." % key) + if processor is not None: + return processor(self._row[index]) + else: + return self._row[index] + + def __getattr__(self, name): + try: + return self[name] + except KeyError, e: + raise AttributeError(e.args[0]) + + +class RowProxy(BaseRowProxy): + """Proxy values from a single cursor row. + + Mostly follows "ordered dictionary" behavior, mapping result + values to the string-based column name, the integer position of + the result in the row, as well as Column instances which can be + mapped to the original Columns that produced this result set (for + results that correspond to constructed SQL expressions). + """ + __slots__ = () + + def __contains__(self, key): + return self._parent._has_key(self._row, key) + + def __getstate__(self): + return { + '_parent': self._parent, + '_row': tuple(self) + } + + def __setstate__(self, state): + self._parent = parent = state['_parent'] + self._row = state['_row'] + self._processors = parent._processors + self._keymap = parent._keymap + + __hash__ = None + + def __eq__(self, other): + return other is self or other == tuple(self) + + def __ne__(self, other): + return not self.__eq__(other) + + def __repr__(self): + return repr(tuple(self)) + + def has_key(self, key): + """Return True if this RowProxy contains the given key.""" + + return self._parent._has_key(self._row, key) + + def items(self): + """Return a list of tuples, each tuple containing a key/value pair.""" + # TODO: no coverage here + return [(key, self[key]) for key in self.iterkeys()] + + def keys(self): + """Return the list of keys as strings represented by this RowProxy.""" + + return self._parent.keys + + def iterkeys(self): + return iter(self._parent.keys) + + def itervalues(self): + return iter(self) + +try: + # Register RowProxy with Sequence, + # so sequence protocol is implemented + from collections import Sequence + Sequence.register(RowProxy) +except ImportError: + pass + + +class ResultMetaData(object): + """Handle cursor.description, applying additional info from an execution + context.""" + + def __init__(self, parent, metadata): + self._processors = processors = [] + + # We do not strictly need to store the processor in the key mapping, + # though it is faster in the Python version (probably because of the + # saved attribute lookup self._processors) + self._keymap = keymap = {} + self.keys = [] + context = parent.context + dialect = context.dialect + typemap = dialect.dbapi_type_map + translate_colname = context._translate_colname + self.case_sensitive = dialect.case_sensitive + + # high precedence key values. + primary_keymap = {} + + for i, rec in enumerate(metadata): + colname = rec[0] + coltype = rec[1] + + if dialect.description_encoding: + colname = dialect._description_decoder(colname) + + if translate_colname: + colname, untranslated = translate_colname(colname) + + if dialect.requires_name_normalize: + colname = dialect.normalize_name(colname) + + if context.result_map: + try: + name, obj, type_ = context.result_map[colname + if self.case_sensitive + else colname.lower()] + except KeyError: + name, obj, type_ = \ + colname, None, typemap.get(coltype, types.NULLTYPE) + else: + name, obj, type_ = \ + colname, None, typemap.get(coltype, types.NULLTYPE) + + processor = type_._cached_result_processor(dialect, coltype) + + processors.append(processor) + rec = (processor, obj, i) + + # indexes as keys. This is only needed for the Python version of + # RowProxy (the C version uses a faster path for integer indexes). + primary_keymap[i] = rec + + # populate primary keymap, looking for conflicts. + if primary_keymap.setdefault( + name if self.case_sensitive + else name.lower(), + rec) is not rec: + # place a record that doesn't have the "index" - this + # is interpreted later as an AmbiguousColumnError, + # but only when actually accessed. Columns + # colliding by name is not a problem if those names + # aren't used; integer and ColumnElement access is always + # unambiguous. + primary_keymap[name + if self.case_sensitive + else name.lower()] = (processor, obj, None) + + self.keys.append(colname) + if obj: + for o in obj: + keymap[o] = rec + + if translate_colname and \ + untranslated: + keymap[untranslated] = rec + + # overwrite keymap values with those of the + # high precedence keymap. + keymap.update(primary_keymap) + + if parent._echo: + context.engine.logger.debug( + "Col %r", tuple(x[0] for x in metadata)) + + @util.pending_deprecation("0.8", "sqlite dialect uses " + "_translate_colname() now") + def _set_keymap_synonym(self, name, origname): + """Set a synonym for the given name. + + Some dialects (SQLite at the moment) may use this to + adjust the column names that are significant within a + row. + + """ + rec = (processor, obj, i) = self._keymap[origname if + self.case_sensitive + else origname.lower()] + if self._keymap.setdefault(name, rec) is not rec: + self._keymap[name] = (processor, obj, None) + + def _key_fallback(self, key, raiseerr=True): + map = self._keymap + result = None + if isinstance(key, basestring): + result = map.get(key if self.case_sensitive else key.lower()) + # fallback for targeting a ColumnElement to a textual expression + # this is a rare use case which only occurs when matching text() + # or colummn('name') constructs to ColumnElements, or after a + # pickle/unpickle roundtrip + elif isinstance(key, expression.ColumnElement): + if key._label and ( + key._label + if self.case_sensitive + else key._label.lower()) in map: + result = map[key._label + if self.case_sensitive + else key._label.lower()] + elif hasattr(key, 'name') and ( + key.name + if self.case_sensitive + else key.name.lower()) in map: + # match is only on name. + result = map[key.name + if self.case_sensitive + else key.name.lower()] + # search extra hard to make sure this + # isn't a column/label name overlap. + # this check isn't currently available if the row + # was unpickled. + if result is not None and \ + result[1] is not None: + for obj in result[1]: + if key._compare_name_for_result(obj): + break + else: + result = None + if result is None: + if raiseerr: + raise exc.NoSuchColumnError( + "Could not locate column in row for column '%s'" % + expression._string_or_unprintable(key)) + else: + return None + else: + map[key] = result + return result + + def _has_key(self, row, key): + if key in self._keymap: + return True + else: + return self._key_fallback(key, False) is not None + + def __getstate__(self): + return { + '_pickled_keymap': dict( + (key, index) + for key, (processor, obj, index) in self._keymap.iteritems() + if isinstance(key, (basestring, int)) + ), + 'keys': self.keys, + "case_sensitive": self.case_sensitive, + } + + def __setstate__(self, state): + # the row has been processed at pickling time so we don't need any + # processor anymore + self._processors = [None for _ in xrange(len(state['keys']))] + self._keymap = keymap = {} + for key, index in state['_pickled_keymap'].iteritems(): + # not preserving "obj" here, unfortunately our + # proxy comparison fails with the unpickle + keymap[key] = (None, None, index) + self.keys = state['keys'] + self.case_sensitive = state['case_sensitive'] + self._echo = False + + +class ResultProxy(object): + """Wraps a DB-API cursor object to provide easier access to row columns. + + Individual columns may be accessed by their integer position, + case-insensitive column name, or by ``schema.Column`` + object. e.g.:: + + row = fetchone() + + col1 = row[0] # access via integer position + + col2 = row['col2'] # access via name + + col3 = row[mytable.c.mycol] # access via Column object. + + ``ResultProxy`` also handles post-processing of result column + data using ``TypeEngine`` objects, which are referenced from + the originating SQL statement that produced this result set. + + """ + + _process_row = RowProxy + out_parameters = None + _can_close_connection = False + + def __init__(self, context): + self.context = context + self.dialect = context.dialect + self.closed = False + self.cursor = self._saved_cursor = context.cursor + self.connection = context.root_connection + self._echo = self.connection._echo and \ + context.engine._should_log_debug() + self._init_metadata() + + def _init_metadata(self): + metadata = self._cursor_description() + if metadata is None: + self._metadata = None + else: + self._metadata = ResultMetaData(self, metadata) + + def keys(self): + """Return the current set of string keys for rows.""" + if self._metadata: + return self._metadata.keys + else: + return [] + + @util.memoized_property + def rowcount(self): + """Return the 'rowcount' for this result. + + The 'rowcount' reports the number of rows *matched* + by the WHERE criterion of an UPDATE or DELETE statement. + + .. note:: + + Notes regarding :attr:`.ResultProxy.rowcount`: + + + * This attribute returns the number of rows *matched*, + which is not necessarily the same as the number of rows + that were actually *modified* - an UPDATE statement, for example, + may have no net change on a given row if the SET values + given are the same as those present in the row already. + Such a row would be matched but not modified. + On backends that feature both styles, such as MySQL, + rowcount is configured by default to return the match + count in all cases. + + * :attr:`.ResultProxy.rowcount` is *only* useful in conjunction + with an UPDATE or DELETE statement. Contrary to what the Python + DBAPI says, it does *not* return the + number of rows available from the results of a SELECT statement + as DBAPIs cannot support this functionality when rows are + unbuffered. + + * :attr:`.ResultProxy.rowcount` may not be fully implemented by + all dialects. In particular, most DBAPIs do not support an + aggregate rowcount result from an executemany call. + The :meth:`.ResultProxy.supports_sane_rowcount` and + :meth:`.ResultProxy.supports_sane_multi_rowcount` methods + will report from the dialect if each usage is known to be + supported. + + * Statements that use RETURNING may not return a correct + rowcount. + + """ + try: + return self.context.rowcount + except Exception, e: + self.connection._handle_dbapi_exception( + e, None, None, self.cursor, self.context) + raise + + @property + def lastrowid(self): + """return the 'lastrowid' accessor on the DBAPI cursor. + + This is a DBAPI specific method and is only functional + for those backends which support it, for statements + where it is appropriate. It's behavior is not + consistent across backends. + + Usage of this method is normally unnecessary when + using insert() expression constructs; the + :attr:`~ResultProxy.inserted_primary_key` attribute provides a + tuple of primary key values for a newly inserted row, + regardless of database backend. + + """ + try: + return self._saved_cursor.lastrowid + except Exception, e: + self.connection._handle_dbapi_exception( + e, None, None, + self._saved_cursor, self.context) + raise + + @property + def returns_rows(self): + """True if this :class:`.ResultProxy` returns rows. + + I.e. if it is legal to call the methods + :meth:`~.ResultProxy.fetchone`, + :meth:`~.ResultProxy.fetchmany` + :meth:`~.ResultProxy.fetchall`. + + """ + return self._metadata is not None + + @property + def is_insert(self): + """True if this :class:`.ResultProxy` is the result + of a executing an expression language compiled + :func:`.expression.insert` construct. + + When True, this implies that the + :attr:`inserted_primary_key` attribute is accessible, + assuming the statement did not include + a user defined "returning" construct. + + """ + return self.context.isinsert + + def _cursor_description(self): + """May be overridden by subclasses.""" + + return self._saved_cursor.description + + def close(self, _autoclose_connection=True): + """Close this ResultProxy. + + Closes the underlying DBAPI cursor corresponding to the execution. + + Note that any data cached within this ResultProxy is still available. + For some types of results, this may include buffered rows. + + If this ResultProxy was generated from an implicit execution, + the underlying Connection will also be closed (returns the + underlying DBAPI connection to the connection pool.) + + This method is called automatically when: + + * all result rows are exhausted using the fetchXXX() methods. + * cursor.description is None. + + """ + + if not self.closed: + self.closed = True + self.connection._safe_close_cursor(self.cursor) + if _autoclose_connection and \ + self.connection.should_close_with_result: + self.connection.close() + # allow consistent errors + self.cursor = None + + def __iter__(self): + while True: + row = self.fetchone() + if row is None: + raise StopIteration + else: + yield row + + @util.memoized_property + def inserted_primary_key(self): + """Return the primary key for the row just inserted. + + The return value is a list of scalar values + corresponding to the list of primary key columns + in the target table. + + This only applies to single row :func:`.insert` + constructs which did not explicitly specify + :meth:`.Insert.returning`. + + Note that primary key columns which specify a + server_default clause, + or otherwise do not qualify as "autoincrement" + columns (see the notes at :class:`.Column`), and were + generated using the database-side default, will + appear in this list as ``None`` unless the backend + supports "returning" and the insert statement executed + with the "implicit returning" enabled. + + Raises :class:`.InvalidRequestError` if the executed + statement is not a compiled expression construct + or is not an insert() construct. + + """ + + if not self.context.compiled: + raise exc.InvalidRequestError( + "Statement is not a compiled " + "expression construct.") + elif not self.context.isinsert: + raise exc.InvalidRequestError( + "Statement is not an insert() " + "expression construct.") + elif self.context._is_explicit_returning: + raise exc.InvalidRequestError( + "Can't call inserted_primary_key " + "when returning() " + "is used.") + + return self.context.inserted_primary_key + + def last_updated_params(self): + """Return the collection of updated parameters from this + execution. + + Raises :class:`.InvalidRequestError` if the executed + statement is not a compiled expression construct + or is not an update() construct. + + """ + if not self.context.compiled: + raise exc.InvalidRequestError( + "Statement is not a compiled " + "expression construct.") + elif not self.context.isupdate: + raise exc.InvalidRequestError( + "Statement is not an update() " + "expression construct.") + elif self.context.executemany: + return self.context.compiled_parameters + else: + return self.context.compiled_parameters[0] + + def last_inserted_params(self): + """Return the collection of inserted parameters from this + execution. + + Raises :class:`.InvalidRequestError` if the executed + statement is not a compiled expression construct + or is not an insert() construct. + + """ + if not self.context.compiled: + raise exc.InvalidRequestError( + "Statement is not a compiled " + "expression construct.") + elif not self.context.isinsert: + raise exc.InvalidRequestError( + "Statement is not an insert() " + "expression construct.") + elif self.context.executemany: + return self.context.compiled_parameters + else: + return self.context.compiled_parameters[0] + + def lastrow_has_defaults(self): + """Return ``lastrow_has_defaults()`` from the underlying + :class:`.ExecutionContext`. + + See :class:`.ExecutionContext` for details. + + """ + + return self.context.lastrow_has_defaults() + + def postfetch_cols(self): + """Return ``postfetch_cols()`` from the underlying + :class:`.ExecutionContext`. + + See :class:`.ExecutionContext` for details. + + Raises :class:`.InvalidRequestError` if the executed + statement is not a compiled expression construct + or is not an insert() or update() construct. + + """ + + if not self.context.compiled: + raise exc.InvalidRequestError( + "Statement is not a compiled " + "expression construct.") + elif not self.context.isinsert and not self.context.isupdate: + raise exc.InvalidRequestError( + "Statement is not an insert() or update() " + "expression construct.") + return self.context.postfetch_cols + + def prefetch_cols(self): + """Return ``prefetch_cols()`` from the underlying + :class:`.ExecutionContext`. + + See :class:`.ExecutionContext` for details. + + Raises :class:`.InvalidRequestError` if the executed + statement is not a compiled expression construct + or is not an insert() or update() construct. + + """ + + if not self.context.compiled: + raise exc.InvalidRequestError( + "Statement is not a compiled " + "expression construct.") + elif not self.context.isinsert and not self.context.isupdate: + raise exc.InvalidRequestError( + "Statement is not an insert() or update() " + "expression construct.") + return self.context.prefetch_cols + + def supports_sane_rowcount(self): + """Return ``supports_sane_rowcount`` from the dialect. + + See :attr:`.ResultProxy.rowcount` for background. + + """ + + return self.dialect.supports_sane_rowcount + + def supports_sane_multi_rowcount(self): + """Return ``supports_sane_multi_rowcount`` from the dialect. + + See :attr:`.ResultProxy.rowcount` for background. + + """ + + return self.dialect.supports_sane_multi_rowcount + + def _fetchone_impl(self): + try: + return self.cursor.fetchone() + except AttributeError: + self._non_result() + + def _fetchmany_impl(self, size=None): + try: + if size is None: + return self.cursor.fetchmany() + else: + return self.cursor.fetchmany(size) + except AttributeError: + self._non_result() + + def _fetchall_impl(self): + try: + return self.cursor.fetchall() + except AttributeError: + self._non_result() + + def _non_result(self): + if self._metadata is None: + raise exc.ResourceClosedError( + "This result object does not return rows. " + "It has been closed automatically.", + ) + else: + raise exc.ResourceClosedError("This result object is closed.") + + def process_rows(self, rows): + process_row = self._process_row + metadata = self._metadata + keymap = metadata._keymap + processors = metadata._processors + if self._echo: + log = self.context.engine.logger.debug + l = [] + for row in rows: + log("Row %r", row) + l.append(process_row(metadata, row, processors, keymap)) + return l + else: + return [process_row(metadata, row, processors, keymap) + for row in rows] + + def fetchall(self): + """Fetch all rows, just like DB-API ``cursor.fetchall()``.""" + + try: + l = self.process_rows(self._fetchall_impl()) + self.close() + return l + except Exception, e: + self.connection._handle_dbapi_exception( + e, None, None, + self.cursor, self.context) + raise + + def fetchmany(self, size=None): + """Fetch many rows, just like DB-API + ``cursor.fetchmany(size=cursor.arraysize)``. + + If rows are present, the cursor remains open after this is called. + Else the cursor is automatically closed and an empty list is returned. + + """ + + try: + l = self.process_rows(self._fetchmany_impl(size)) + if len(l) == 0: + self.close() + return l + except Exception, e: + self.connection._handle_dbapi_exception( + e, None, None, + self.cursor, self.context) + raise + + def fetchone(self): + """Fetch one row, just like DB-API ``cursor.fetchone()``. + + If a row is present, the cursor remains open after this is called. + Else the cursor is automatically closed and None is returned. + + """ + try: + row = self._fetchone_impl() + if row is not None: + return self.process_rows([row])[0] + else: + self.close() + return None + except Exception, e: + self.connection._handle_dbapi_exception( + e, None, None, + self.cursor, self.context) + raise + + def first(self): + """Fetch the first row and then close the result set unconditionally. + + Returns None if no row is present. + + """ + if self._metadata is None: + self._non_result() + + try: + row = self._fetchone_impl() + except Exception, e: + self.connection._handle_dbapi_exception( + e, None, None, + self.cursor, self.context) + raise + + try: + if row is not None: + return self.process_rows([row])[0] + else: + return None + finally: + self.close() + + def scalar(self): + """Fetch the first column of the first row, and close the result set. + + Returns None if no row is present. + + """ + row = self.first() + if row is not None: + return row[0] + else: + return None + +class BufferedRowResultProxy(ResultProxy): + """A ResultProxy with row buffering behavior. + + ``ResultProxy`` that buffers the contents of a selection of rows + before ``fetchone()`` is called. This is to allow the results of + ``cursor.description`` to be available immediately, when + interfacing with a DB-API that requires rows to be consumed before + this information is available (currently psycopg2, when used with + server-side cursors). + + The pre-fetching behavior fetches only one row initially, and then + grows its buffer size by a fixed amount with each successive need + for additional rows up to a size of 100. + """ + + def _init_metadata(self): + self.__buffer_rows() + super(BufferedRowResultProxy, self)._init_metadata() + + # this is a "growth chart" for the buffering of rows. + # each successive __buffer_rows call will use the next + # value in the list for the buffer size until the max + # is reached + size_growth = { + 1: 5, + 5: 10, + 10: 20, + 20: 50, + 50: 100, + 100: 250, + 250: 500, + 500: 1000 + } + + def __buffer_rows(self): + size = getattr(self, '_bufsize', 1) + self.__rowbuffer = collections.deque(self.cursor.fetchmany(size)) + self._bufsize = self.size_growth.get(size, size) + + def _fetchone_impl(self): + if self.closed: + return None + if not self.__rowbuffer: + self.__buffer_rows() + if not self.__rowbuffer: + return None + return self.__rowbuffer.popleft() + + def _fetchmany_impl(self, size=None): + if size is None: + return self._fetchall_impl() + result = [] + for x in range(0, size): + row = self._fetchone_impl() + if row is None: + break + result.append(row) + return result + + def _fetchall_impl(self): + self.__rowbuffer.extend(self.cursor.fetchall()) + ret = self.__rowbuffer + self.__rowbuffer = collections.deque() + return ret + + +class FullyBufferedResultProxy(ResultProxy): + """A result proxy that buffers rows fully upon creation. + + Used for operations where a result is to be delivered + after the database conversation can not be continued, + such as MSSQL INSERT...OUTPUT after an autocommit. + + """ + def _init_metadata(self): + super(FullyBufferedResultProxy, self)._init_metadata() + self.__rowbuffer = self._buffer_rows() + + def _buffer_rows(self): + return collections.deque(self.cursor.fetchall()) + + def _fetchone_impl(self): + if self.__rowbuffer: + return self.__rowbuffer.popleft() + else: + return None + + def _fetchmany_impl(self, size=None): + if size is None: + return self._fetchall_impl() + result = [] + for x in range(0, size): + row = self._fetchone_impl() + if row is None: + break + result.append(row) + return result + + def _fetchall_impl(self): + ret = self.__rowbuffer + self.__rowbuffer = collections.deque() + return ret + +class BufferedColumnRow(RowProxy): + def __init__(self, parent, row, processors, keymap): + # preprocess row + row = list(row) + # this is a tad faster than using enumerate + index = 0 + for processor in parent._orig_processors: + if processor is not None: + row[index] = processor(row[index]) + index += 1 + row = tuple(row) + super(BufferedColumnRow, self).__init__(parent, row, + processors, keymap) + + +class BufferedColumnResultProxy(ResultProxy): + """A ResultProxy with column buffering behavior. + + ``ResultProxy`` that loads all columns into memory each time + fetchone() is called. If fetchmany() or fetchall() are called, + the full grid of results is fetched. This is to operate with + databases where result rows contain "live" results that fall out + of scope unless explicitly fetched. Currently this includes + cx_Oracle LOB objects. + + """ + + _process_row = BufferedColumnRow + + def _init_metadata(self): + super(BufferedColumnResultProxy, self)._init_metadata() + metadata = self._metadata + # orig_processors will be used to preprocess each row when they are + # constructed. + metadata._orig_processors = metadata._processors + # replace the all type processors by None processors. + metadata._processors = [None for _ in xrange(len(metadata.keys))] + keymap = {} + for k, (func, obj, index) in metadata._keymap.iteritems(): + keymap[k] = (None, obj, index) + self._metadata._keymap = keymap + + def fetchall(self): + # can't call cursor.fetchall(), since rows must be + # fully processed before requesting more from the DBAPI. + l = [] + while True: + row = self.fetchone() + if row is None: + break + l.append(row) + return l + + def fetchmany(self, size=None): + # can't call cursor.fetchmany(), since rows must be + # fully processed before requesting more from the DBAPI. + if size is None: + return self.fetchall() + l = [] + for i in xrange(size): + row = self.fetchone() + if row is None: + break + l.append(row) + return l |