合并连接(Merge Join) 谈到合并连接,我突然想起在西雅图参加SQL Pass峰会晚上酒吧排队点酒,由于我和另外一哥们站错了位置,貌似我们两个在插队一样,我赶紧说:I’m sorry,i thought here is end of line。对方无不幽默的说:”It’s OK,In SQL Server,We called it merge join”。 由上面的小故事不难看出,M...
SQLSERVER SQL TDE数据库加密操作一、创建master数据库下的主数据库密钥在Transact-SQL下执行USE masterCREATE MASTER KEY ENCRYPTION BY PASSWORD = N'master主数据密钥密码';二、创建证书用来保护数据库加密密钥在Transact-SQL下执行USE masterCREATE CERTIFICATE mas sql server 存储过程 加密 sql 数据库 SQL 主数据 ...
sql server 执行计划 hash match sql执行计划命令 Explain命令在解决数据库性能上是第一推荐使用命令,大部分的性能问题可以通过此命令来简单的解决,Explain可以用来查看SQL语句的执行效 果,可以帮助选择更好的索引和优化查询语句,写出更好的优化语句。 EXPLAIN 语法:explain select … from … [where …] EXPLAIN PART...
假设你正在使用 Microsoft SQL Server 中的传输层安全(TLS)协议版本1.2。 当用于加密数据库镜像、可用性组和 service broker 的终结点通信的证书使用 MD5 哈希算法时,通信将失败。 此外,你还会在 SQL Server 错误日志中收到以下错误消息: 连接握手失败。 操作...
This feature is off by default, and it is only available in SQL Server 2022 CU12 and later. There are no plans to back-port this to older versions of the database engine. Next, and this is critically important. This changes the on-disk format for the password ve...
MySQL8.0以后,Server层做了大量的优化。HashJoin的支持使得MySQL优化器有更多选择,SQL的执行路径也能做到更优,尤其是对于等值join的场景。虽然MySQL之前对于Join做过若干优化,比如NBLJ,INLJ等,但这些代替不了HashJoin的作用。一个好用的数据库就应该具备丰富的基础能力,利用优化器分析,结合具体的业务查询场景,更好的...
这篇文章:Improvement in minimizing lockhash key collisions in SQL Server 2008R2 and its impact on concurrency Since the key to a row could be as large as 900 bytes, using the real key values would have inflicted larger memory consumption. ...
If you need hash functions that spread data evenly over an integer space, you have to choose the hash function carefully. The built in hash functions BINARY_CHECKSUM and CHECKSUM, while very fast, do not provide a good spread over a 16 bit integer space. The built in SQL Server HASHBYTES...
参考MySQL介绍Hash Join的示例,例如SQL: 1234 SELECT given_name,country_nameFROM persons JOIN countries ON persons.country_id= countries.country_id; 1.1 Basic Hash Join(In-memory Hash Join) 内存能够存储外表时,可以直接依赖内存执行Basic Hash Join,所以又被称为In-memory Hash Join。执行Hash Join一般包...
version 1.2 in Microsoft SQL Server. When the certificate that's used to encrypt the endpoint communication for database mirroring, availability groups, and service broker uses an MD5 hashing algorithm, communication fails. Additionally, you receive...