# oracle.py # Copyright (C) 2005, 2006, 2007, 2008, 2009 Michael Bayer mike_mp@zzzcomputing.com # # This module is part of SQLAlchemy and is released under # the MIT License: http://www.opensource.org/licenses/mit-license.php """Support for the Oracle database. Oracle version 8 through current (11g at the time of this writing) are supported. Driver ------ The Oracle dialect uses the cx_oracle driver, available at http://cx-oracle.sourceforge.net/ . The dialect has several behaviors which are specifically tailored towards compatibility with this module. Connecting ---------- Connecting with create_engine() uses the standard URL approach of ``oracle://user:pass@host:port/dbname[?key=value&key=value...]``. If dbname is present, the host, port, and dbname tokens are converted to a TNS name using the cx_oracle :func:`makedsn()` function. Otherwise, the host token is taken directly as a TNS name. Additional arguments which may be specified either as query string arguments on the URL, or as keyword arguments to :func:`~sqlalchemy.create_engine()` are: * *allow_twophase* - enable two-phase transactions. Defaults to ``True``. * *auto_convert_lobs* - defaults to True, see the section on LOB objects. * *auto_setinputsizes* - the cx_oracle.setinputsizes() call is issued for all bind parameters. This is required for LOB datatypes but can be disabled to reduce overhead. Defaults to ``True``. * *mode* - This is given the string value of SYSDBA or SYSOPER, or alternatively an integer value. This value is only available as a URL query string argument. * *threaded* - enable multithreaded access to cx_oracle connections. Defaults to ``True``. Note that this is the opposite default of cx_oracle itself. * *use_ansi* - Use ANSI JOIN constructs (see the section on Oracle 8). Defaults to ``True``. If ``False``, Oracle-8 compatible constructs are used for joins. * *optimize_limits* - defaults to ``False``. see the section on LIMIT/OFFSET. Auto Increment Behavior ----------------------- SQLAlchemy Table objects which include integer primary keys are usually assumed to have "autoincrementing" behavior, meaning they can generate their own primary key values upon INSERT. Since Oracle has no "autoincrement" feature, SQLAlchemy relies upon sequences to produce these values. With the Oracle dialect, *a sequence must always be explicitly specified to enable autoincrement*. This is divergent with the majority of documentation examples which assume the usage of an autoincrement-capable database. To specify sequences, use the sqlalchemy.schema.Sequence object which is passed to a Column construct:: t = Table('mytable', metadata, Column('id', Integer, Sequence('id_seq'), primary_key=True), Column(...), ... ) This step is also required when using table reflection, i.e. autoload=True:: t = Table('mytable', metadata, Column('id', Integer, Sequence('id_seq'), primary_key=True), autoload=True ) LOB Objects ----------- cx_oracle presents some challenges when fetching LOB objects. A LOB object in a result set is presented by cx_oracle as a cx_oracle.LOB object which has a read() method. By default, SQLAlchemy converts these LOB objects into Python strings. This is for two reasons. First, the LOB object requires an active cursor association, meaning if you were to fetch many rows at once such that cx_oracle had to go back to the database and fetch a new batch of rows, the LOB objects in the already-fetched rows are now unreadable and will raise an error. SQLA "pre-reads" all LOBs so that their data is fetched before further rows are read. The size of a "batch of rows" is controlled by the cursor.arraysize value, which SQLAlchemy defaults to 50 (cx_oracle normally defaults this to one). Secondly, the LOB object is not a standard DBAPI return value so SQLAlchemy seeks to "normalize" the results to look more like other DBAPIs. The conversion of LOB objects by this dialect is unique in SQLAlchemy in that it takes place for all statement executions, even plain string-based statements for which SQLA has no awareness of result typing. This is so that calls like fetchmany() and fetchall() can work in all cases without raising cursor errors. The conversion of LOB in all cases, as well as the "prefetch" of LOB objects, can be disabled using auto_convert_lobs=False. LIMIT/OFFSET Support -------------------- Oracle has no support for the LIMIT or OFFSET keywords. Whereas previous versions of SQLAlchemy used the "ROW NUMBER OVER..." construct to simulate LIMIT/OFFSET, SQLAlchemy 0.5 now uses a wrapped subquery approach in conjunction with ROWNUM. The exact methodology is taken from http://www.oracle.com/technology/oramag/oracle/06-sep/o56asktom.html . Note that the "FIRST ROWS()" optimization keyword mentioned is not used by default, as the user community felt this was stepping into the bounds of optimization that is better left on the DBA side, but this prefix can be added by enabling the optimize_limits=True flag on create_engine(). Two Phase Transaction Support ----------------------------- Two Phase transactions are implemented using XA transactions. Success has been reported of them working successfully but this should be regarded as an experimental feature. Oracle 8 Compatibility ---------------------- When using Oracle 8, a "use_ansi=False" flag is available which converts all JOIN phrases into the WHERE clause, and in the case of LEFT OUTER JOIN makes use of Oracle's (+) operator. Synonym/DBLINK Reflection ------------------------- When using reflection with Table objects, the dialect can optionally search for tables indicated by synonyms that reference DBLINK-ed tables by passing the flag oracle_resolve_synonyms=True as a keyword argument to the Table construct. If DBLINK is not in use this flag should be left off. """ import datetime, random, re from sqlalchemy import util, sql, schema, log from sqlalchemy.engine import default, base from sqlalchemy.sql import compiler, visitors, expression from sqlalchemy.sql import operators as sql_operators, functions as sql_functions from sqlalchemy import types as sqltypes class OracleNumeric(sqltypes.Numeric): def get_col_spec(self): if self.precision is None: return "NUMERIC" else: return "NUMERIC(%(precision)s, %(scale)s)" % {'precision': self.precision, 'scale' : self.scale} class OracleInteger(sqltypes.Integer): def get_col_spec(self): return "INTEGER" class OracleSmallInteger(sqltypes.Smallinteger): def get_col_spec(self): return "SMALLINT" class OracleDate(sqltypes.Date): def get_col_spec(self): return "DATE" def bind_processor(self, dialect): return None def result_processor(self, dialect): def process(value): if not isinstance(value, datetime.datetime): return value else: return value.date() return process class OracleDateTime(sqltypes.DateTime): def get_col_spec(self): return "DATE" def result_processor(self, dialect): def process(value): if value is None or isinstance(value, datetime.datetime): return value else: # convert cx_oracle datetime object returned pre-python 2.4 return datetime.datetime(value.year, value.month, value.day,value.hour, value.minute, value.second) return process # Note: # Oracle DATE == DATETIME # Oracle does not allow milliseconds in DATE # Oracle does not support TIME columns # only if cx_oracle contains TIMESTAMP class OracleTimestamp(sqltypes.TIMESTAMP): def get_col_spec(self): return "TIMESTAMP" def get_dbapi_type(self, dialect): return dialect.TIMESTAMP def result_processor(self, dialect): def process(value): if value is None or isinstance(value, datetime.datetime): return value else: # convert cx_oracle datetime object returned pre-python 2.4 return datetime.datetime(value.year, value.month, value.day,value.hour, value.minute, value.second) return process class OracleString(sqltypes.String): def get_col_spec(self): return "VARCHAR(%(length)s)" % {'length' : self.length} class OracleNVarchar(sqltypes.Unicode, OracleString): def get_col_spec(self): return "NVARCHAR2(%(length)s)" % {'length' : self.length} class OracleText(sqltypes.Text): def get_dbapi_type(self, dbapi): return dbapi.CLOB def get_col_spec(self): return "CLOB" def result_processor(self, dialect): super_process = super(OracleText, self).result_processor(dialect) if not dialect.auto_convert_lobs: return super_process lob = dialect.dbapi.LOB def process(value): if isinstance(value, lob): if super_process: return super_process(value.read()) else: return value.read() else: if super_process: return super_process(value) else: return value return process class OracleChar(sqltypes.CHAR): def get_col_spec(self): return "CHAR(%(length)s)" % {'length' : self.length} class OracleBinary(sqltypes.Binary): def get_dbapi_type(self, dbapi): return dbapi.BLOB def get_col_spec(self): return "BLOB" def bind_processor(self, dialect): return None def result_processor(self, dialect): if not dialect.auto_convert_lobs: return None lob = dialect.dbapi.LOB def process(value): if isinstance(value, lob): return value.read() else: return value return process class OracleRaw(OracleBinary): def get_col_spec(self): return "RAW(%(length)s)" % {'length' : self.length} class OracleBoolean(sqltypes.Boolean): def get_col_spec(self): return "SMALLINT" def result_processor(self, dialect): def process(value): if value is None: return None return value and True or False return process def bind_processor(self, dialect): def process(value): if value is True: return 1 elif value is False: return 0 elif value is None: return None else: return value and True or False return process colspecs = { sqltypes.Integer : OracleInteger, sqltypes.Smallinteger : OracleSmallInteger, sqltypes.Numeric : OracleNumeric, sqltypes.Float : OracleNumeric, sqltypes.DateTime : OracleDateTime, sqltypes.Date : OracleDate, sqltypes.String : OracleString, sqltypes.Binary : OracleBinary, sqltypes.Boolean : OracleBoolean, sqltypes.Text : OracleText, sqltypes.TIMESTAMP : OracleTimestamp, sqltypes.CHAR: OracleChar, } ischema_names = { 'VARCHAR2' : OracleString, 'NVARCHAR2' : OracleNVarchar, 'CHAR' : OracleString, 'DATE' : OracleDateTime, 'DATETIME' : OracleDateTime, 'NUMBER' : OracleNumeric, 'BLOB' : OracleBinary, 'BFILE' : OracleBinary, 'CLOB' : OracleText, 'TIMESTAMP' : OracleTimestamp, 'RAW' : OracleRaw, 'FLOAT' : OracleNumeric, 'DOUBLE PRECISION' : OracleNumeric, 'LONG' : OracleText, } class OracleExecutionContext(default.DefaultExecutionContext): def pre_exec(self): super(OracleExecutionContext, self).pre_exec() if self.dialect.auto_setinputsizes: self.set_input_sizes() if self.compiled_parameters is not None and len(self.compiled_parameters) == 1: for key in self.compiled.binds: bindparam = self.compiled.binds[key] name = self.compiled.bind_names[bindparam] value = self.compiled_parameters[0][name] if bindparam.isoutparam: dbtype = bindparam.type.dialect_impl(self.dialect).get_dbapi_type(self.dialect.dbapi) if not hasattr(self, 'out_parameters'): self.out_parameters = {} self.out_parameters[name] = self.cursor.var(dbtype) self.parameters[0][name] = self.out_parameters[name] def create_cursor(self): c = self._connection.connection.cursor() if self.dialect.arraysize: c.cursor.arraysize = self.dialect.arraysize return c def get_result_proxy(self): if hasattr(self, 'out_parameters'): if self.compiled_parameters is not None and len(self.compiled_parameters) == 1: for bind, name in self.compiled.bind_names.iteritems(): if name in self.out_parameters: type = bind.type result_processor = type.dialect_impl(self.dialect).result_processor(self.dialect) if result_processor is not None: self.out_parameters[name] = result_processor(self.out_parameters[name].getvalue()) else: self.out_parameters[name] = self.out_parameters[name].getvalue() else: for k in self.out_parameters: self.out_parameters[k] = self.out_parameters[k].getvalue() if self.cursor.description is not None: for column in self.cursor.description: type_code = column[1] if type_code in self.dialect.ORACLE_BINARY_TYPES: return base.BufferedColumnResultProxy(self) return base.ResultProxy(self) class OracleDialect(default.DefaultDialect): name = 'oracle' supports_alter = True supports_unicode_statements = False max_identifier_length = 30 supports_sane_rowcount = True supports_sane_multi_rowcount = False preexecute_pk_sequences = True supports_pk_autoincrement = False default_paramstyle = 'named' def __init__(self, use_ansi=True, auto_setinputsizes=True, auto_convert_lobs=True, threaded=True, allow_twophase=True, optimize_limits=False, arraysize=50, **kwargs): default.DefaultDialect.__init__(self, **kwargs) self.use_ansi = use_ansi self.threaded = threaded self.arraysize = arraysize self.allow_twophase = allow_twophase self.optimize_limits = optimize_limits self.supports_timestamp = self.dbapi is None or hasattr(self.dbapi, 'TIMESTAMP' ) self.auto_setinputsizes = auto_setinputsizes self.auto_convert_lobs = auto_convert_lobs if self.dbapi is None or not self.auto_convert_lobs or not 'CLOB' in self.dbapi.__dict__: self.dbapi_type_map = {} self.ORACLE_BINARY_TYPES = [] else: # only use this for LOB objects. using it for strings, dates # etc. leads to a little too much magic, reflection doesn't know if it should # expect encoded strings or unicodes, etc. self.dbapi_type_map = { self.dbapi.CLOB: OracleText(), self.dbapi.BLOB: OracleBinary(), self.dbapi.BINARY: OracleRaw(), } self.ORACLE_BINARY_TYPES = [getattr(self.dbapi, k) for k in ["BFILE", "CLOB", "NCLOB", "BLOB"] if hasattr(self.dbapi, k)] def dbapi(cls): import cx_Oracle return cx_Oracle dbapi = classmethod(dbapi) def create_connect_args(self, url): dialect_opts = dict(url.query) for opt in ('use_ansi', 'auto_setinputsizes', 'auto_convert_lobs', 'threaded', 'allow_twophase'): if opt in dialect_opts: util.coerce_kw_type(dialect_opts, opt, bool) setattr(self, opt, dialect_opts[opt]) if url.database: # if we have a database, then we have a remote host port = url.port if port: port = int(port) else: port = 1521 dsn = self.dbapi.makedsn(url.host, port, url.database) else: # we have a local tnsname dsn = url.host opts = dict( user=url.username, password=url.password, dsn=dsn, threaded=self.threaded, twophase=self.allow_twophase, ) if 'mode' in url.query: opts['mode'] = url.query['mode'] if isinstance(opts['mode'], basestring): mode = opts['mode'].upper() if mode == 'SYSDBA': opts['mode'] = self.dbapi.SYSDBA elif mode == 'SYSOPER': opts['mode'] = self.dbapi.SYSOPER else: util.coerce_kw_type(opts, 'mode', int) # Can't set 'handle' or 'pool' via URL query args, use connect_args return ([], opts) def is_disconnect(self, e): if isinstance(e, self.dbapi.InterfaceError): return "not connected" in str(e) else: return "ORA-03114" in str(e) or "ORA-03113" in str(e) def type_descriptor(self, typeobj): return sqltypes.adapt_type(typeobj, colspecs) def create_xid(self): """create a two-phase transaction ID. this id will be passed to do_begin_twophase(), do_rollback_twophase(), do_commit_twophase(). its format is unspecified.""" id = random.randint(0, 2 ** 128) return (0x1234, "%032x" % id, "%032x" % 9) def do_release_savepoint(self, connection, name): # Oracle does not support RELEASE SAVEPOINT pass def do_begin_twophase(self, connection, xid): connection.connection.begin(*xid) def do_prepare_twophase(self, connection, xid): connection.connection.prepare() def do_rollback_twophase(self, connection, xid, is_prepared=True, recover=False): self.do_rollback(connection.connection) def do_commit_twophase(self, connection, xid, is_prepared=True, recover=False): self.do_commit(connection.connection) def do_recover_twophase(self, connection): pass def has_table(self, connection, table_name, schema=None): if not schema: schema = self.get_default_schema_name(connection) cursor = connection.execute("""select table_name from all_tables where table_name=:name and owner=:schema_name""", {'name':self._denormalize_name(table_name), 'schema_name':self._denormalize_name(schema)}) return cursor.fetchone() is not None def has_sequence(self, connection, sequence_name, schema=None): if not schema: schema = self.get_default_schema_name(connection) cursor = connection.execute("""select sequence_name from all_sequences where sequence_name=:name and sequence_owner=:schema_name""", {'name':self._denormalize_name(sequence_name), 'schema_name':self._denormalize_name(schema)}) return cursor.fetchone() is not None def _normalize_name(self, name): if name is None: return None elif name.upper() == name and not self.identifier_preparer._requires_quotes(name.lower().decode(self.encoding)): return name.lower().decode(self.encoding) else: return name.decode(self.encoding) def _denormalize_name(self, name): if name is None: return None elif name.lower() == name and not self.identifier_preparer._requires_quotes(name.lower()): return name.upper().encode(self.encoding) else: return name.encode(self.encoding) def get_default_schema_name(self, connection): return self._normalize_name(connection.execute('SELECT USER FROM DUAL').scalar()) get_default_schema_name = base.connection_memoize( ('dialect', 'default_schema_name'))(get_default_schema_name) def table_names(self, connection, schema): # note that table_names() isnt loading DBLINKed or synonym'ed tables if schema is None: s = "select table_name from all_tables where nvl(tablespace_name, 'no tablespace') NOT IN ('SYSTEM', 'SYSAUX')" cursor = connection.execute(s) else: s = "select table_name from all_tables where nvl(tablespace_name, 'no tablespace') NOT IN ('SYSTEM','SYSAUX') AND OWNER = :owner" cursor = connection.execute(s, {'owner': self._denormalize_name(schema)}) return [self._normalize_name(row[0]) for row in cursor] def _resolve_synonym(self, connection, desired_owner=None, desired_synonym=None, desired_table=None): """search for a local synonym matching the given desired owner/name. if desired_owner is None, attempts to locate a distinct owner. returns the actual name, owner, dblink name, and synonym name if found. """ sql = """select OWNER, TABLE_OWNER, TABLE_NAME, DB_LINK, SYNONYM_NAME from ALL_SYNONYMS WHERE """ clauses = [] params = {} if desired_synonym: clauses.append("SYNONYM_NAME=:synonym_name") params['synonym_name'] = desired_synonym if desired_owner: clauses.append("TABLE_OWNER=:desired_owner") params['desired_owner'] = desired_owner if desired_table: clauses.append("TABLE_NAME=:tname") params['tname'] = desired_table sql += " AND ".join(clauses) result = connection.execute(sql, **params) if desired_owner: row = result.fetchone() if row: return row['TABLE_NAME'], row['TABLE_OWNER'], row['DB_LINK'], row['SYNONYM_NAME'] else: return None, None, None, None else: rows = result.fetchall() if len(rows) > 1: raise AssertionError("There are multiple tables visible to the schema, you must specify owner") elif len(rows) == 1: row = rows[0] return row['TABLE_NAME'], row['TABLE_OWNER'], row['DB_LINK'], row['SYNONYM_NAME'] else: return None, None, None, None def reflecttable(self, connection, table, include_columns): preparer = self.identifier_preparer resolve_synonyms = table.kwargs.get('oracle_resolve_synonyms', False) if resolve_synonyms: actual_name, owner, dblink, synonym = self._resolve_synonym(connection, desired_owner=self._denormalize_name(table.schema), desired_synonym=self._denormalize_name(table.name)) else: actual_name, owner, dblink, synonym = None, None, None, None if not actual_name: actual_name = self._denormalize_name(table.name) if not dblink: dblink = '' if not owner: owner = self._denormalize_name(table.schema or self.get_default_schema_name(connection)) c = connection.execute ("select COLUMN_NAME, DATA_TYPE, DATA_LENGTH, DATA_PRECISION, DATA_SCALE, NULLABLE, DATA_DEFAULT from ALL_TAB_COLUMNS%(dblink)s where TABLE_NAME = :table_name and OWNER = :owner" % {'dblink':dblink}, {'table_name':actual_name, 'owner':owner}) while True: row = c.fetchone() if row is None: break (colname, coltype, length, precision, scale, nullable, default) = (self._normalize_name(row[0]), row[1], row[2], row[3], row[4], row[5]=='Y', row[6]) if include_columns and colname not in include_columns: continue # INTEGER if the scale is 0 and precision is null # NUMBER if the scale and precision are both null # NUMBER(9,2) if the precision is 9 and the scale is 2 # NUMBER(3) if the precision is 3 and scale is 0 #length is ignored except for CHAR and VARCHAR2 if coltype == 'NUMBER' : if precision is None and scale is None: coltype = OracleNumeric elif precision is None and scale == 0 : coltype = OracleInteger else : coltype = OracleNumeric(precision, scale) elif coltype=='CHAR' or coltype=='VARCHAR2': coltype = ischema_names.get(coltype, OracleString)(length) else: coltype = re.sub(r'\(\d+\)', '', coltype) try: coltype = ischema_names[coltype] except KeyError: util.warn("Did not recognize type '%s' of column '%s'" % (coltype, colname)) coltype = sqltypes.NULLTYPE colargs = [] if default is not None: colargs.append(schema.DefaultClause(sql.text(default))) table.append_column(schema.Column(colname, coltype, nullable=nullable, *colargs)) if not table.columns: raise AssertionError("Couldn't find any column information for table %s" % actual_name) c = connection.execute("""SELECT ac.constraint_name, ac.constraint_type, loc.column_name AS local_column, rem.table_name AS remote_table, rem.column_name AS remote_column, rem.owner AS remote_owner FROM all_constraints%(dblink)s ac, all_cons_columns%(dblink)s loc, all_cons_columns%(dblink)s rem WHERE ac.table_name = :table_name AND ac.constraint_type IN ('R','P') AND ac.owner = :owner AND ac.owner = loc.owner AND ac.constraint_name = loc.constraint_name AND ac.r_owner = rem.owner(+) AND ac.r_constraint_name = rem.constraint_name(+) -- order multiple primary keys correctly ORDER BY ac.constraint_name, loc.position, rem.position""" % {'dblink':dblink}, {'table_name' : actual_name, 'owner' : owner}) fks = {} while True: row = c.fetchone() if row is None: break #print "ROW:" , row (cons_name, cons_type, local_column, remote_table, remote_column, remote_owner) = row[0:2] + tuple([self._normalize_name(x) for x in row[2:]]) if cons_type == 'P': table.primary_key.add(table.c[local_column]) elif cons_type == 'R': try: fk = fks[cons_name] except KeyError: fk = ([], []) fks[cons_name] = fk if remote_table is None: # ticket 363 util.warn( ("Got 'None' querying 'table_name' from " "all_cons_columns%(dblink)s - does the user have " "proper rights to the table?") % {'dblink':dblink}) continue if resolve_synonyms: ref_remote_name, ref_remote_owner, ref_dblink, ref_synonym = self._resolve_synonym(connection, desired_owner=self._denormalize_name(remote_owner), desired_table=self._denormalize_name(remote_table)) if ref_synonym: remote_table = self._normalize_name(ref_synonym) remote_owner = self._normalize_name(ref_remote_owner) if not table.schema and self._denormalize_name(remote_owner) == owner: refspec = ".".join([remote_table, remote_column]) t = schema.Table(remote_table, table.metadata, autoload=True, autoload_with=connection, oracle_resolve_synonyms=resolve_synonyms, useexisting=True) else: refspec = ".".join([x for x in [remote_owner, remote_table, remote_column] if x]) t = schema.Table(remote_table, table.metadata, autoload=True, autoload_with=connection, schema=remote_owner, oracle_resolve_synonyms=resolve_synonyms, useexisting=True) if local_column not in fk[0]: fk[0].append(local_column) if refspec not in fk[1]: fk[1].append(refspec) for name, value in fks.iteritems(): table.append_constraint(schema.ForeignKeyConstraint(value[0], value[1], name=name, link_to_name=True)) class _OuterJoinColumn(sql.ClauseElement): __visit_name__ = 'outer_join_column' def __init__(self, column): self.column = column class OracleCompiler(compiler.DefaultCompiler): """Oracle compiler modifies the lexical structure of Select statements to work under non-ANSI configured Oracle databases, if the use_ansi flag is False. """ operators = compiler.DefaultCompiler.operators.copy() operators.update( { sql_operators.mod : lambda x, y:"mod(%s, %s)" % (x, y), sql_operators.match_op: lambda x, y: "CONTAINS (%s, %s)" % (x, y) } ) functions = compiler.DefaultCompiler.functions.copy() functions.update ( { sql_functions.now : 'CURRENT_TIMESTAMP' } ) def __init__(self, *args, **kwargs): super(OracleCompiler, self).__init__(*args, **kwargs) self.__wheres = {} def default_from(self): """Called when a ``SELECT`` statement has no froms, and no ``FROM`` clause is to be appended. The Oracle compiler tacks a "FROM DUAL" to the statement. """ return " FROM DUAL" def apply_function_parens(self, func): return len(func.clauses) > 0 def visit_join(self, join, **kwargs): if self.dialect.use_ansi: return compiler.DefaultCompiler.visit_join(self, join, **kwargs) else: return self.process(join.left, asfrom=True) + ", " + self.process(join.right, asfrom=True) def _get_nonansi_join_whereclause(self, froms): clauses = [] def visit_join(join): if join.isouter: def visit_binary(binary): if binary.operator == sql_operators.eq: if binary.left.table is join.right: binary.left = _OuterJoinColumn(binary.left) elif binary.right.table is join.right: binary.right = _OuterJoinColumn(binary.right) clauses.append(visitors.cloned_traverse(join.onclause, {}, {'binary':visit_binary})) else: clauses.append(join.onclause) for f in froms: visitors.traverse(f, {}, {'join':visit_join}) return sql.and_(*clauses) def visit_outer_join_column(self, vc): return self.process(vc.column) + "(+)" def visit_sequence(self, seq): return self.dialect.identifier_preparer.format_sequence(seq) + ".nextval" def visit_alias(self, alias, asfrom=False, **kwargs): """Oracle doesn't like ``FROM table AS alias``. Is the AS standard SQL??""" if asfrom: alias_name = isinstance(alias.name, expression._generated_label) and \ self._truncated_identifier("alias", alias.name) or alias.name return self.process(alias.original, asfrom=True, **kwargs) + " " +\ self.preparer.format_alias(alias, alias_name) else: return self.process(alias.original, **kwargs) def _TODO_visit_compound_select(self, select): """Need to determine how to get ``LIMIT``/``OFFSET`` into a ``UNION`` for Oracle.""" pass def visit_select(self, select, **kwargs): """Look for ``LIMIT`` and OFFSET in a select statement, and if so tries to wrap it in a subquery with ``rownum`` criterion. """ if not getattr(select, '_oracle_visit', None): if not self.dialect.use_ansi: if self.stack and 'from' in self.stack[-1]: existingfroms = self.stack[-1]['from'] else: existingfroms = None froms = select._get_display_froms(existingfroms) whereclause = self._get_nonansi_join_whereclause(froms) if whereclause: select = select.where(whereclause) select._oracle_visit = True if select._limit is not None or select._offset is not None: # See http://www.oracle.com/technology/oramag/oracle/06-sep/o56asktom.html # # Generalized form of an Oracle pagination query: # select ... from ( # select /*+ FIRST_ROWS(N) */ ...., rownum as ora_rn from ( # select distinct ... where ... order by ... # ) where ROWNUM <= :limit+:offset # ) where ora_rn > :offset # Outer select and "ROWNUM as ora_rn" can be dropped if limit=0 # TODO: use annotations instead of clone + attr set ? select = select._generate() select._oracle_visit = True # Wrap the middle select and add the hint limitselect = sql.select([c for c in select.c]) if select._limit and self.dialect.optimize_limits: limitselect = limitselect.prefix_with("/*+ FIRST_ROWS(%d) */" % select._limit) limitselect._oracle_visit = True limitselect._is_wrapper = True # If needed, add the limiting clause if select._limit is not None: max_row = select._limit if select._offset is not None: max_row += select._offset limitselect.append_whereclause( sql.literal_column("ROWNUM")<=max_row) # If needed, add the ora_rn, and wrap again with offset. if select._offset is None: select = limitselect else: limitselect = limitselect.column( sql.literal_column("ROWNUM").label("ora_rn")) limitselect._oracle_visit = True limitselect._is_wrapper = True offsetselect = sql.select( [c for c in limitselect.c if c.key!='ora_rn']) offsetselect._oracle_visit = True offsetselect._is_wrapper = True offsetselect.append_whereclause( sql.literal_column("ora_rn")>select._offset) select = offsetselect kwargs['iswrapper'] = getattr(select, '_is_wrapper', False) return compiler.DefaultCompiler.visit_select(self, select, **kwargs) def limit_clause(self, select): return "" def for_update_clause(self, select): if select.for_update == "nowait": return " FOR UPDATE NOWAIT" else: return super(OracleCompiler, self).for_update_clause(select) class OracleSchemaGenerator(compiler.SchemaGenerator): def get_column_specification(self, column, **kwargs): colspec = self.preparer.format_column(column) colspec += " " + column.type.dialect_impl(self.dialect).get_col_spec() default = self.get_column_default_string(column) if default is not None: colspec += " DEFAULT " + default if not column.nullable: colspec += " NOT NULL" return colspec def visit_sequence(self, sequence): if not self.checkfirst or not self.dialect.has_sequence(self.connection, sequence.name, sequence.schema): self.append("CREATE SEQUENCE %s" % self.preparer.format_sequence(sequence)) self.execute() class OracleSchemaDropper(compiler.SchemaDropper): def visit_sequence(self, sequence): if not self.checkfirst or self.dialect.has_sequence(self.connection, sequence.name, sequence.schema): self.append("DROP SEQUENCE %s" % self.preparer.format_sequence(sequence)) self.execute() class OracleDefaultRunner(base.DefaultRunner): def visit_sequence(self, seq): return self.execute_string("SELECT " + self.dialect.identifier_preparer.format_sequence(seq) + ".nextval FROM DUAL", {}) class OracleIdentifierPreparer(compiler.IdentifierPreparer): def format_savepoint(self, savepoint): name = re.sub(r'^_+', '', savepoint.ident) return super(OracleIdentifierPreparer, self).format_savepoint(savepoint, name) dialect = OracleDialect dialect.statement_compiler = OracleCompiler dialect.schemagenerator = OracleSchemaGenerator dialect.schemadropper = OracleSchemaDropper dialect.preparer = OracleIdentifierPreparer dialect.defaultrunner = OracleDefaultRunner dialect.execution_ctx_cls = OracleExecutionContext