Python db.DB_RMW屬性代碼示例

# 需要導入模塊: from bsddb import db [as 別名]
# 或者: from bsddb.db import DB_RMW [as 別名]
def CreateTable(self, table, columns):
        """CreateTable(table, columns) - Create a new table in the database.

        raises TableDBError if it already exists or for other DB errors.
        """
        assert isinstance(columns, list)

        txn = None
        try:
            # checking sanity of the table and column names here on
            # table creation will prevent problems elsewhere.
            if contains_metastrings(table):
                raise ValueError(
                    "bad table name: contains reserved metastrings")
            for column in columns :
                if contains_metastrings(column):
                    raise ValueError(
                        "bad column name: contains reserved metastrings")

            columnlist_key = _columns_key(table)
            if getattr(self.db, "has_key")(columnlist_key):
                raise TableAlreadyExists, "table already exists"

            txn = self.env.txn_begin()
            # store the table's column info
            getattr(self.db, "put_bytes", self.db.put)(columnlist_key,
                    pickle.dumps(columns, 1), txn=txn)

            # add the table name to the tablelist
            tablelist = pickle.loads(getattr(self.db, "get_bytes",
                self.db.get) (_table_names_key, txn=txn, flags=db.DB_RMW))
            tablelist.append(table)
            # delete 1st, in case we opened with DB_DUP
            self.db.delete(_table_names_key, txn=txn)
            getattr(self.db, "put_bytes", self.db.put)(_table_names_key,
                    pickle.dumps(tablelist, 1), txn=txn)

            txn.commit()
            txn = None
        except db.DBError, dberror:
            if txn:
                txn.abort()
            if sys.version_info < (2, 6) :
                raise TableDBError, dberror[1]
            else :
                raise TableDBError, dberror.args[1] 

# 需要導入模塊: from bsddb import db [as 別名]
# 或者: from bsddb.db import DB_RMW [as 別名]
def CreateOrExtendTable(self, table, columns):
        """CreateOrExtendTable(table, columns)

        Create a new table in the database.

        If a table of this name already exists, extend it to have any
        additional columns present in the given list as well as
        all of its current columns.
        """
        assert isinstance(columns, list)

        try:
            self.CreateTable(table, columns)
        except TableAlreadyExists:
            # the table already existed, add any new columns
            txn = None
            try:
                columnlist_key = _columns_key(table)
                txn = self.env.txn_begin()

                # load the current column list
                oldcolumnlist = pickle.loads(
                    getattr(self.db, "get_bytes",
                        self.db.get)(columnlist_key, txn=txn, flags=db.DB_RMW))
                # create a hash table for fast lookups of column names in the
                # loop below
                oldcolumnhash = {}
                for c in oldcolumnlist:
                    oldcolumnhash[c] = c

                # create a new column list containing both the old and new
                # column names
                newcolumnlist = copy.copy(oldcolumnlist)
                for c in columns:
                    if not c in oldcolumnhash:
                        newcolumnlist.append(c)

                # store the table's new extended column list
                if newcolumnlist != oldcolumnlist :
                    # delete the old one first since we opened with DB_DUP
                    self.db.delete(columnlist_key, txn=txn)
                    getattr(self.db, "put_bytes", self.db.put)(columnlist_key,
                                pickle.dumps(newcolumnlist, 1),
                                txn=txn)

                txn.commit()
                txn = None

                self.__load_column_info(table)
            except db.DBError, dberror:
                if txn:
                    txn.abort()
                if sys.version_info < (2, 6) :
                    raise TableDBError, dberror[1]
                else :
                    raise TableDBError, dberror.args[1] 

# 需要導入模塊: from bsddb import db [as 別名]
# 或者: from bsddb.db import DB_RMW [as 別名]
def Drop(self, table):
        """Remove an entire table from the database"""
        txn = None
        try:
            txn = self.env.txn_begin()

            # delete the column list
            self.db.delete(_columns_key(table), txn=txn)

            cur = self.db.cursor(txn)

            # delete all keys containing this tables column and row info
            table_key = _search_all_data_key(table)
            while 1:
                try:
                    key, data = cur.set_range(table_key)
                except db.DBNotFoundError:
                    break
                # only delete items in this table
                if key[:len(table_key)] != table_key:
                    break
                cur.delete()

            # delete all rowids used by this table
            table_key = _search_rowid_key(table)
            while 1:
                try:
                    key, data = cur.set_range(table_key)
                except db.DBNotFoundError:
                    break
                # only delete items in this table
                if key[:len(table_key)] != table_key:
                    break
                cur.delete()

            cur.close()

            # delete the tablename from the table name list
            tablelist = pickle.loads(
                getattr(self.db, "get_bytes", self.db.get)(_table_names_key,
                    txn=txn, flags=db.DB_RMW))
            try:
                tablelist.remove(table)
            except ValueError:
                # hmm, it wasn't there, oh well, that's what we want.
                pass
            # delete 1st, incase we opened with DB_DUP
            self.db.delete(_table_names_key, txn=txn)
            getattr(self.db, "put_bytes", self.db.put)(_table_names_key,
                    pickle.dumps(tablelist, 1), txn=txn)

            txn.commit()
            txn = None

            if table in self.__tablecolumns:
                del self.__tablecolumns[table]

        except db.DBError, dberror:
            if txn:
                txn.abort()
            raise TableDBError(dberror.args[1])