oracle编程艺术 笔记（oracle编程艺术 笔记）.docVIP

oracle编程艺术 笔记（oracle编程艺术 笔记） What are the database architectures, how databases work, and how they behave? What is concurrency control and what does concurrency control mean? Problems such as development, performance, scalability, and safety must be properly considered when developing What are the characteristics of a particular database and how do you use it? Good SQL statement Doubt Database can be achieved, why not let the database do, so that my application can be deployed anywhere, I think no server does not support Oracle, why, why do you have to implement it again? There are inefficient SQL; there are a lot of procedural code, but these work was originally a SQL statement is enough; in order to maintain database independence, there is no Use new features How do you tune SQL without modifying SQL?. This may seem magical, but it can be done in Oracle 10g, which is, to a great extent, the first. How to measure performance. How do I see where bottlenecks occur?. How to build indexes and index what?. And so on. crux Databases are often the cornerstone of application. If it doesnt work well, nothing else will make sense SGV Area Global (System) Oracle will parse, compiled SQL here, try to use bound variables, you can use SGV to smooth operation Bind variables: select *, from, table, where, id=: ID Soft analysis Hard parsing: taking more resources, locking longer Oracle lock: Locks only when modified. Normally, it does not upgrade to block level locks and table level locks, but there is one other thing: a short period of time for the two commit; If you simply read data, Oracle will never lock the data and will not lock on the data rows because of simple read operations; One point distinguished from other data: the writer does not block the reader The original text of the book: The following is a summary of the Oracle locking policy: Oracle only when the data was modified in the lock. Normally, it does not upgrade to block level locks or table level locks (except for