Init: 用于SeqScan没有子执行器,将该函数放空即可。 Next: TableHeap为我们提供了MakeIterator(), IsEnd()与operator++(), 使用迭代器遍历。TableHeap即可。不过你不能输出(1)被删除的tuple, (2)不符合filter的tuple。 值得注意的是:(1)BusTub删除了TableIterator的拷贝方法,我们只能为SeqScanExecutor添加TableIte...
此外,LRUKNode 除LRUKNode(size_t k, frame_id_t fid) 外还需要指定默认构造函数 LRUKNode() = default,因为在 LRUKReplacer 使用std::unordered_map 的operator[] 时,若指定的键不存在于映射中,会首先调用 LRUKNode 的默认构造,然后才会报错。要么定义LRUKNode的默认构造,要么使用emplace插入。 2. LRUK...
当 DBMS 调用执行器的 Next 函数时,执行器会返回 (1) 单个元组 或者 (2) 没有更多的元组的指示。通过这种方法,每个执行器实现了一个循环,持续调用其子节点的 Next 函数来逐个检索和处理元组。在BusTub 的迭代器模型实现中,每个执行器的 Next 函数除了返回一个元组外,还会返回一个记录标识符(Record Identifier,...
'QUERY REWRITE', 'CREATE DIMENSION', 'CREATE INDEXTYPE', 'CREATE LIBRARY', 'CREATE OPERATOR', 'CREATE PROCEDURE', 'CREATE SEQUENCE', 'CREATE SESSION', 'CREATE SNAPSHOT
In Oracle Database 10g Release 2, you can create the wrapped code directly without a script by calling the supplied procedure: Copy Copied to Clipboard Error: Could not Copy begin dbms_ddl.create_wrapped ('create or replace function myfunc ...') end; You can also use this to write your...
迭代器接口:Begin End operator++ 并发控制:利用TransactionManager实现INSERT,UPDATE,SELECT,DELETE的并发版本和乐观锁版本 二、实现细节 A concurrency control protocol is the method that the DBMS uses to ensure “correct” results for concurrent operations on a shared object. ...
Depending on the field type many logic operator are available: equals, does not equals, is greater than, is greater than or equal to, is less than, is less than or equal to, is not within, is within, contains, does not contains. The custom views are now available under the menu ...
LBADD - Distributed SQL database implemented in Go go-memdb - In-memory database based on immutable radix trees VectorSQL - DBMS database for IoT and Big Data, similar to ClickHouse BuntDB - A memory-based KV database that supports disk persistence and ACID transactions TinySQL - Small dist...
PostgreSQL does not need Oracle’s table 'dual', but since it is intensively used by Oracle users, it has been added in orafce. Package dbms_output PostgreSQL sends information to the client via RAISE NOTICE. Oracle uses dbms_output.put_line(). This works differently from RAISE NOTICE. Orac...
awhere H is the Warniltonian of the system and is the symmetrized flux operator. Formally, the trace form of N(E) can be evaluated in any complete basis. Since Eq. 18.47 does not refer to the asymptotic states explicitly, N(E) can be calculated using only dynamics in the transition ...