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# firebird/base.py # Copyright (C) 2005-2021 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 r""" .. dialect:: firebird :name: Firebird .. note:: The Firebird dialect within SQLAlchemy **is not currently supported**. It is not tested within continuous integration and is likely to have many issues and caveats not currently handled. Consider using the `external dialect <https://github.com/pauldex/sqlalchemy-firebird>`_ instead. Firebird Dialects ----------------- Firebird offers two distinct dialects_ (not to be confused with a SQLAlchemy ``Dialect``): dialect 1 This is the old syntax and behaviour, inherited from Interbase pre-6.0. dialect 3 This is the newer and supported syntax, introduced in Interbase 6.0. The SQLAlchemy Firebird dialect detects these versions and adjusts its representation of SQL accordingly. However, support for dialect 1 is not well tested and probably has incompatibilities. Locking Behavior ---------------- Firebird locks tables aggressively. For this reason, a DROP TABLE may hang until other transactions are released. SQLAlchemy does its best to release transactions as quickly as possible. The most common cause of hanging transactions is a non-fully consumed result set, i.e.:: result = engine.execute("select * from table") row = result.fetchone() return Where above, the ``ResultProxy`` has not been fully consumed. The connection will be returned to the pool and the transactional state rolled back once the Python garbage collector reclaims the objects which hold onto the connection, which often occurs asynchronously. The above use case can be alleviated by calling ``first()`` on the ``ResultProxy`` which will fetch the first row and immediately close all remaining cursor/connection resources. RETURNING support ----------------- Firebird 2.0 supports returning a result set from inserts, and 2.1 extends that to deletes and updates. This is generically exposed by the SQLAlchemy ``returning()`` method, such as:: # INSERT..RETURNING result = table.insert().returning(table.c.col1, table.c.col2).\ values(name='foo') print(result.fetchall()) # UPDATE..RETURNING raises = empl.update().returning(empl.c.id, empl.c.salary).\ where(empl.c.sales>100).\ values(dict(salary=empl.c.salary * 1.1)) print(raises.fetchall()) .. _dialects: http://mc-computing.com/Databases/Firebird/SQL_Dialect.html """ import datetime from sqlalchemy import exc from sqlalchemy import sql from sqlalchemy import types as sqltypes from sqlalchemy import util from sqlalchemy.engine import default from sqlalchemy.engine import reflection from sqlalchemy.sql import compiler from sqlalchemy.sql import expression from sqlalchemy.types import BIGINT from sqlalchemy.types import BLOB from sqlalchemy.types import DATE from sqlalchemy.types import FLOAT from sqlalchemy.types import INTEGER from sqlalchemy.types import Integer from sqlalchemy.types import NUMERIC from sqlalchemy.types import SMALLINT from sqlalchemy.types import TEXT from sqlalchemy.types import TIME from sqlalchemy.types import TIMESTAMP RESERVED_WORDS = set( [ "active", "add", "admin", "after", "all", "alter", "and", "any", "as", "asc", "ascending", "at", "auto", "avg", "before", "begin", "between", "bigint", "bit_length", "blob", "both", "by", "case", "cast", "char", "character", "character_length", "char_length", "check", "close", "collate", "column", "commit", "committed", "computed", "conditional", "connect", "constraint", "containing", "count", "create", "cross", "cstring", "current", "current_connection", "current_date", "current_role", "current_time", "current_timestamp", "current_transaction", "current_user", "cursor", "database", "date", "day", "dec", "decimal", "declare", "default", "delete", "desc", "descending", "disconnect", "distinct", "do", "domain", "double", "drop", "else", "end", "entry_point", "escape", "exception", "execute", "exists", "exit", "external", "extract", "fetch", "file", "filter", "float", "for", "foreign", "from", "full", "function", "gdscode", "generator", "gen_id", "global", "grant", "group", "having", "hour", "if", "in", "inactive", "index", "inner", "input_type", "insensitive", "insert", "int", "integer", "into", "is", "isolation", "join", "key", "leading", "left", "length", "level", "like", "long", "lower", "manual", "max", "maximum_segment", "merge", "min", "minute", "module_name", "month", "names", "national", "natural", "nchar", "no", "not", "null", "numeric", "octet_length", "of", "on", "only", "open", "option", "or", "order", "outer", "output_type", "overflow", "page", "pages", "page_size", "parameter", "password", "plan", "position", "post_event", "precision", "primary", "privileges", "procedure", "protected", "rdb$db_key", "read", "real", "record_version", "recreate", "recursive", "references", "release", "reserv", "reserving", "retain", "returning_values", "returns", "revoke", "right", "rollback", "rows", "row_count", "savepoint", "schema", "second", "segment", "select", "sensitive", "set", "shadow", "shared", "singular", "size", "smallint", "snapshot", "some", "sort", "sqlcode", "stability", "start", "starting", "starts", "statistics", "sub_type", "sum", "suspend", "table", "then", "time", "timestamp", "to", "trailing", "transaction", "trigger", "trim", "uncommitted", "union", "unique", "update", "upper", "user", "using", "value", "values", "varchar", "variable", "varying", "view", "wait", "when", "where", "while", "with", "work", "write", "year", ] ) class _StringType(sqltypes.String): """Base for Firebird string types.""" def __init__(self, charset=None, **kw): self.charset = charset super(_StringType, self).__init__(**kw) class VARCHAR(_StringType, sqltypes.VARCHAR): """Firebird VARCHAR type""" __visit_name__ = "VARCHAR" def __init__(self, length=None, **kwargs): super(VARCHAR, self).__init__(length=length, **kwargs) class CHAR(_StringType, sqltypes.CHAR): """Firebird CHAR type""" __visit_name__ = "CHAR" def __init__(self, length=None, **kwargs): super(CHAR, self).__init__(length=length, **kwargs) class _FBDateTime(sqltypes.DateTime): def bind_processor(self, dialect): def process(value): if type(value) == datetime.date: return datetime.datetime(value.year, value.month, value.day) else: return value return process colspecs = {sqltypes.DateTime: _FBDateTime} ischema_names = { "SHORT": SMALLINT, "LONG": INTEGER, "QUAD": FLOAT, "FLOAT": FLOAT, "DATE": DATE, "TIME": TIME, "TEXT": TEXT, "INT64": BIGINT, "DOUBLE": FLOAT, "TIMESTAMP": TIMESTAMP, "VARYING": VARCHAR, "CSTRING": CHAR, "BLOB": BLOB, } # TODO: date conversion types (should be implemented as _FBDateTime, # _FBDate, etc. as bind/result functionality is required) class FBTypeCompiler(compiler.GenericTypeCompiler): def visit_boolean(self, type_, **kw): return self.visit_SMALLINT(type_, **kw) def visit_datetime(self, type_, **kw): return self.visit_TIMESTAMP(type_, **kw) def visit_TEXT(self, type_, **kw): return "BLOB SUB_TYPE 1" def visit_BLOB(self, type_, **kw): return "BLOB SUB_TYPE 0" def _extend_string(self, type_, basic): charset = getattr(type_, "charset", None) if charset is None: return basic else: return "%s CHARACTER SET %s" % (basic, charset) def visit_CHAR(self, type_, **kw): basic = super(FBTypeCompiler, self).visit_CHAR(type_, **kw) return self._extend_string(type_, basic) def visit_VARCHAR(self, type_, **kw): if not type_.length: raise exc.CompileError( "VARCHAR requires a length on dialect %s" % self.dialect.name ) basic = super(FBTypeCompiler, self).visit_VARCHAR(type_, **kw) return self._extend_string(type_, basic) class FBCompiler(sql.compiler.SQLCompiler): """Firebird specific idiosyncrasies""" ansi_bind_rules = True # def visit_contains_op_binary(self, binary, operator, **kw): # cant use CONTAINING b.c. it's case insensitive. # def visit_notcontains_op_binary(self, binary, operator, **kw): # cant use NOT CONTAINING b.c. it's case insensitive. def visit_now_func(self, fn, **kw): return "CURRENT_TIMESTAMP" def visit_startswith_op_binary(self, binary, operator, **kw): return "%s STARTING WITH %s" % ( binary.left._compiler_dispatch(self, **kw), binary.right._compiler_dispatch(self, **kw), ) def visit_notstartswith_op_binary(self, binary, operator, **kw): return "%s NOT STARTING WITH %s" % ( binary.left._compiler_dispatch(self, **kw), binary.right._compiler_dispatch(self, **kw), ) def visit_mod_binary(self, binary, operator, **kw): return "mod(%s, %s)" % ( self.process(binary.left, **kw), self.process(binary.right, **kw), ) def visit_alias(self, alias, asfrom=False, **kwargs): if self.dialect._version_two: return super(FBCompiler, self).visit_alias( alias, asfrom=asfrom, **kwargs ) else: # Override to not use the AS keyword which FB 1.5 does not like if asfrom: alias_name = ( isinstance(alias.name, expression._truncated_label) and self._truncated_identifier("alias", alias.name) or alias.name ) return ( self.process(alias.original, asfrom=asfrom, **kwargs) + " " + self.preparer.format_alias(alias, alias_name) ) else: return self.process(alias.original, **kwargs) def visit_substring_func(self, func, **kw): s = self.process(func.clauses.clauses[0]) start = self.process(func.clauses.clauses[1]) if len(func.clauses.clauses) > 2: length = self.process(func.clauses.clauses[2]) return "SUBSTRING(%s FROM %s FOR %s)" % (s, start, length) else: return "SUBSTRING(%s FROM %s)" % (s, start) def visit_length_func(self, function, **kw): if self.dialect._version_two: return "char_length" + self.function_argspec(function) else: return "strlen" + self.function_argspec(function) visit_char_length_func = visit_length_func def function_argspec(self, func, **kw): # TODO: this probably will need to be # narrowed to a fixed list, some no-arg functions # may require parens - see similar example in the oracle # dialect if func.clauses is not None and len(func.clauses): return self.process(func.clause_expr, **kw) else: return "" def default_from(self): return " FROM rdb$database" def visit_sequence(self, seq, **kw): return "gen_id(%s, 1)" % self.preparer.format_sequence(seq) def get_select_precolumns(self, select, **kw): """Called when building a ``SELECT`` statement, position is just before column list Firebird puts the limit and offset right after the ``SELECT``... """ result = "" if select._limit_clause is not None: result += "FIRST %s " % self.process(select._limit_clause, **kw) if select._offset_clause is not None: result += "SKIP %s " % self.process(select._offset_clause, **kw) if select._distinct: result += "DISTINCT " return result def limit_clause(self, select, **kw): """Already taken care of in the `get_select_precolumns` method.""" return "" def returning_clause(self, stmt, returning_cols): columns = [ self._label_select_column(None, c, True, False, {}) for c in expression._select_iterables(returning_cols) ] return "RETURNING " + ", ".join(columns) class FBDDLCompiler(sql.compiler.DDLCompiler): """Firebird syntactic idiosyncrasies""" def visit_create_sequence(self, create): """Generate a ``CREATE GENERATOR`` statement for the sequence.""" # no syntax for these # http://www.firebirdsql.org/manual/generatorguide-sqlsyntax.html if create.element.start is not None: raise NotImplementedError( "Firebird SEQUENCE doesn't support START WITH" ) if create.element.increment is not None: raise NotImplementedError( "Firebird SEQUENCE doesn't support INCREMENT BY" ) if self.dialect._version_two: return "CREATE SEQUENCE %s" % self.preparer.format_sequence( create.element ) else: return "CREATE GENERATOR %s" % self.preparer.format_sequence( create.element ) def visit_drop_sequence(self, drop): """Generate a ``DROP GENERATOR`` statement for the sequence.""" if self.dialect._version_two: return "DROP SEQUENCE %s" % self.preparer.format_sequence( drop.element ) else: return "DROP GENERATOR %s" % self.preparer.format_sequence( drop.element ) def visit_computed_column(self, generated): if generated.persisted is not None: raise exc.CompileError( "Firebird computed columns do not support a persistence " "method setting; set the 'persisted' flag to None for " "Firebird support." ) return "GENERATED ALWAYS AS (%s)" % self.sql_compiler.process( generated.sqltext, include_table=False, literal_binds=True ) class FBIdentifierPreparer(sql.compiler.IdentifierPreparer): """Install Firebird specific reserved words.""" reserved_words = RESERVED_WORDS illegal_initial_characters = compiler.ILLEGAL_INITIAL_CHARACTERS.union( ["_"] ) def __init__(self, dialect): super(FBIdentifierPreparer, self).__init__(dialect, omit_schema=True) class FBExecutionContext(default.DefaultExecutionContext): def fire_sequence(self, seq, type_): """Get the next value from the sequence using ``gen_id()``.""" return self._execute_scalar( "SELECT gen_id(%s, 1) FROM rdb$database" % self.identifier_preparer.format_sequence(seq), type_, ) class FBDialect(default.DefaultDialect): """Firebird dialect""" name = "firebird" max_identifier_length = 31 supports_sequences = True sequences_optional = False supports_default_values = True postfetch_lastrowid = False supports_native_boolean = False requires_name_normalize = True supports_empty_insert = False statement_compiler = FBCompiler ddl_compiler = FBDDLCompiler preparer = FBIdentifierPreparer type_compiler = FBTypeCompiler execution_ctx_cls = FBExecutionContext colspecs = colspecs ischema_names = ischema_names construct_arguments = [] # defaults to dialect ver. 3, # will be autodetected off upon # first connect _version_two = True def initialize(self, connection): super(FBDialect, self).initialize(connection) self._version_two = ( "firebird" in self.server_version_info and self.server_version_info >= (2,) ) or ( "interbase" in self.server_version_info and self.server_version_info >= (6,) ) if not self._version_two: # TODO: whatever other pre < 2.0 stuff goes here self.ischema_names = ischema_names.copy() self.ischema_names["TIMESTAMP"] = sqltypes.DATE self.colspecs = {sqltypes.DateTime: sqltypes.DATE} self.implicit_returning = self._version_two and self.__dict__.get( "implicit_returning", True ) def has_table(self, connection, table_name, schema=None): """Return ``True`` if the given table exists, ignoring the `schema`.""" tblqry = """ SELECT 1 AS has_table FROM rdb$database WHERE EXISTS (SELECT rdb$relation_name FROM rdb$relations WHERE rdb$relation_name=?) """ c = connection.execute(tblqry, [self.denormalize_name(table_name)]) return c.first() is not None def has_sequence(self, connection, sequence_name, schema=None): """Return ``True`` if the given sequence (generator) exists.""" genqry = """ SELECT 1 AS has_sequence FROM rdb$database WHERE EXISTS (SELECT rdb$generator_name FROM rdb$generators WHERE rdb$generator_name=?) """ c = connection.execute(genqry, [self.denormalize_name(sequence_name)]) return c.first() is not None @reflection.cache def get_table_names(self, connection, schema=None, **kw): # there are two queries commonly mentioned for this. # this one, using view_blr, is at the Firebird FAQ among other places: # http://www.firebirdfaq.org/faq174/ s = """ select rdb$relation_name from rdb$relations where rdb$view_blr is null and (rdb$system_flag is null or rdb$system_flag = 0); """ # the other query is this one. It's not clear if there's really # any difference between these two. This link: # http://www.alberton.info/firebird_sql_meta_info.html#.Ur3vXfZGni8 # states them as interchangeable. Some discussion at [ticket:2898] # SELECT DISTINCT rdb$relation_name # FROM rdb$relation_fields # WHERE rdb$system_flag=0 AND rdb$view_context IS NULL return [self.normalize_name(row[0]) for row in connection.execute(s)] @reflection.cache def get_view_names(self, connection, schema=None, **kw): # see http://www.firebirdfaq.org/faq174/ s = """ select rdb$relation_name from rdb$relations where rdb$view_blr is not null and (rdb$system_flag is null or rdb$system_flag = 0); """ return [self.normalize_name(row[0]) for row in connection.execute(s)] @reflection.cache def get_view_definition(self, connection, view_name, schema=None, **kw): qry = """ SELECT rdb$view_source AS view_source FROM rdb$relations WHERE rdb$relation_name=? """ rp = connection.execute(qry, [self.denormalize_name(view_name)]) row = rp.first() if row: return row["view_source"] else: return None @reflection.cache def get_pk_constraint(self, connection, table_name, schema=None, **kw): # Query to extract the PK/FK constrained fields of the given table keyqry = """ SELECT se.rdb$field_name AS fname FROM rdb$relation_constraints rc JOIN rdb$index_segments se ON rc.rdb$index_name=se.rdb$index_name WHERE rc.rdb$constraint_type=? AND rc.rdb$relation_name=? """ tablename = self.denormalize_name(table_name) # get primary key fields c = connection.execute(keyqry, ["PRIMARY KEY", tablename]) pkfields = [self.normalize_name(r["fname"]) for r in c.fetchall()] return {"constrained_columns": pkfields, "name": None} @reflection.cache def get_column_sequence( self, connection, table_name, column_name, schema=None, **kw ): tablename = self.denormalize_name(table_name) colname = self.denormalize_name(column_name) # Heuristic-query to determine the generator associated to a PK field genqry = """ SELECT trigdep.rdb$depended_on_name AS fgenerator FROM rdb$dependencies tabdep JOIN rdb$dependencies trigdep ON tabdep.rdb$dependent_name=trigdep.rdb$dependent_name AND trigdep.rdb$depended_on_type=14 AND trigdep.rdb$dependent_type=2 JOIN rdb$triggers trig ON trig.rdb$trigger_name=tabdep.rdb$dependent_name WHERE tabdep.rdb$depended_on_name=? AND tabdep.rdb$depended_on_type=0 AND trig.rdb$trigger_type=1 AND tabdep.rdb$field_name=? AND (SELECT count(*) FROM rdb$dependencies trigdep2 WHERE trigdep2.rdb$dependent_name = trigdep.rdb$dependent_name) = 2 """ genr = connection.execute(genqry, [tablename, colname]).first() if genr is not None: return dict(name=self.normalize_name(genr["fgenerator"])) @reflection.cache def get_columns(self, connection, table_name, schema=None, **kw): # Query to extract the details of all the fields of the given table tblqry = """ SELECT r.rdb$field_name AS fname, r.rdb$null_flag AS null_flag, t.rdb$type_name AS ftype, f.rdb$field_sub_type AS stype, f.rdb$field_length/ COALESCE(cs.rdb$bytes_per_character,1) AS flen, f.rdb$field_precision AS fprec, f.rdb$field_scale AS fscale, COALESCE(r.rdb$default_source, f.rdb$default_source) AS fdefault FROM rdb$relation_fields r JOIN rdb$fields f ON r.rdb$field_source=f.rdb$field_name JOIN rdb$types t ON t.rdb$type=f.rdb$field_type AND t.rdb$field_name='RDB$FIELD_TYPE' LEFT JOIN rdb$character_sets cs ON f.rdb$character_set_id=cs.rdb$character_set_id WHERE f.rdb$system_flag=0 AND r.rdb$relation_name=? ORDER BY r.rdb$field_position """ # get the PK, used to determine the eventual associated sequence pk_constraint = self.get_pk_constraint(connection, table_name) pkey_cols = pk_constraint["constrained_columns"] tablename = self.denormalize_name(table_name) # get all of the fields for this table c = connection.execute(tblqry, [tablename]) cols = [] while True: row = c.fetchone() if row is None: break name = self.normalize_name(row["fname"]) orig_colname = row["fname"] # get the data type colspec = row["ftype"].rstrip() coltype = self.ischema_names.get(colspec) if coltype is None: util.warn( "Did not recognize type '%s' of column '%s'" % (colspec, name) ) coltype = sqltypes.NULLTYPE elif issubclass(coltype, Integer) and row["fprec"] != 0: coltype = NUMERIC( precision=row["fprec"], scale=row["fscale"] * -1 ) elif colspec in ("VARYING", "CSTRING"): coltype = coltype(row["flen"]) elif colspec == "TEXT": coltype = TEXT(row["flen"]) elif colspec == "BLOB": if row["stype"] == 1: coltype = TEXT() else: coltype = BLOB() else: coltype = coltype() # does it have a default value? defvalue = None if row["fdefault"] is not None: # the value comes down as "DEFAULT 'value'": there may be # more than one whitespace around the "DEFAULT" keyword # and it may also be lower case # (see also http://tracker.firebirdsql.org/browse/CORE-356) defexpr = row["fdefault"].lstrip() assert defexpr[:8].rstrip().upper() == "DEFAULT", ( "Unrecognized default value: %s" % defexpr ) defvalue = defexpr[8:].strip() if defvalue == "NULL": # Redundant defvalue = None col_d = { "name": name, "type": coltype, "nullable": not bool(row["null_flag"]), "default": defvalue, "autoincrement": "auto", } if orig_colname.lower() == orig_colname: col_d["quote"] = True # if the PK is a single field, try to see if its linked to # a sequence thru a trigger if len(pkey_cols) == 1 and name == pkey_cols[0]: seq_d = self.get_column_sequence(connection, tablename, name) if seq_d is not None: col_d["sequence"] = seq_d cols.append(col_d) return cols @reflection.cache def get_foreign_keys(self, connection, table_name, schema=None, **kw): # Query to extract the details of each UK/FK of the given table fkqry = """ SELECT rc.rdb$constraint_name AS cname, cse.rdb$field_name AS fname, ix2.rdb$relation_name AS targetrname, se.rdb$field_name AS targetfname FROM rdb$relation_constraints rc JOIN rdb$indices ix1 ON ix1.rdb$index_name=rc.rdb$index_name JOIN rdb$indices ix2 ON ix2.rdb$index_name=ix1.rdb$foreign_key JOIN rdb$index_segments cse ON cse.rdb$index_name=ix1.rdb$index_name JOIN rdb$index_segments se ON se.rdb$index_name=ix2.rdb$index_name AND se.rdb$field_position=cse.rdb$field_position WHERE rc.rdb$constraint_type=? AND rc.rdb$relation_name=? ORDER BY se.rdb$index_name, se.rdb$field_position """ tablename = self.denormalize_name(table_name) c = connection.execute(fkqry, ["FOREIGN KEY", tablename]) fks = util.defaultdict( lambda: { "name": None, "constrained_columns": [], "referred_schema": None, "referred_table": None, "referred_columns": [], } ) for row in c: cname = self.normalize_name(row["cname"]) fk = fks[cname] if not fk["name"]: fk["name"] = cname fk["referred_table"] = self.normalize_name(row["targetrname"]) fk["constrained_columns"].append(self.normalize_name(row["fname"])) fk["referred_columns"].append( self.normalize_name(row["targetfname"]) ) return list(fks.values()) @reflection.cache def get_indexes(self, connection, table_name, schema=None, **kw): qry = """ SELECT ix.rdb$index_name AS index_name, ix.rdb$unique_flag AS unique_flag, ic.rdb$field_name AS field_name FROM rdb$indices ix JOIN rdb$index_segments ic ON ix.rdb$index_name=ic.rdb$index_name LEFT OUTER JOIN rdb$relation_constraints ON rdb$relation_constraints.rdb$index_name = ic.rdb$index_name WHERE ix.rdb$relation_name=? AND ix.rdb$foreign_key IS NULL AND rdb$relation_constraints.rdb$constraint_type IS NULL ORDER BY index_name, ic.rdb$field_position """ c = connection.execute(qry, [self.denormalize_name(table_name)]) indexes = util.defaultdict(dict) for row in c: indexrec = indexes[row["index_name"]] if "name" not in indexrec: indexrec["name"] = self.normalize_name(row["index_name"]) indexrec["column_names"] = [] indexrec["unique"] = bool(row["unique_flag"]) indexrec["column_names"].append( self.normalize_name(row["field_name"]) ) return list(indexes.values())