caohong286的专栏

Chapter 2 SQL Execution     SQL的执行Karen Morton   (page51)    You likely learned the mechanics of writing basic SQL in a relatively short period of time. Over the course of a few weeks or few...

Executing the Plan and Fetching Rows   执行计划和取出行  (page 78)    After the optimizer determines the plan and stores it in the library cache for later reuse, the next step is to actually execute...

Determining the Execution Plan    确定执行计划  (page 74)    When a hard parse occurs, Oracle will determine which execution plan is best for the query.  An execution plan is simply the set of steps...

Query Rewrite with Materialized Views  用物化视图重写查询 (page 72)    Query rewrite is a transformation that occurs when a query, or a portion of a query , has been saved as a materialized v...

Predicate Pushing   谓词推进       (page 69)    Predicate pushing is used to apply the predicates from a containing query block into a non-mergeable query block.  The goal is to allow a...

Subquery Unnesting  子查询反嵌套        (page 66)    Subquery unnesting is similar to view merging in that just like a view a subquery is represented by a separate query block.  The main dif...

View Merging  视图合并  (Page 62)    As the name implies, view merging is a transformation that expands views, either in-line views or stored views, into separate query blocks that can eithe...

Query Transformation    查询变换   (Page 61)    Prior to the development of the execution plan, a step called query transformation occurs. This step happens just after a query is checked for syn...

SGA – The Buffer Cache    SGA-缓冲区缓存   (page59)    The buffer cache is one of the largest components of the SGA. It stores database blocks after they have been read from disk or before ...

2.4 Identical Statements  同样的语句   (page56)    In order for Oracle to determine if a statement has been previously executed, it will check the library cache for the identical statement....

The Library Cache  库缓存     (page 54)    The first thing that must happen to every SQL statement you execute is that it must be parsed andloaded into the library cache.  The library cac...

2.2 SGA – The Shared Pool  共享池 (page 53)    The shared pool is one of the most critical memory components particularly when it comes to how SQL executes. The way you write SQL doesn’t just effect ...

SQL Execution – Putting It All Together   SQL执行--把所有放在一起 (page 81)    Now that I’ve covered the details, I’m ready to put the whole picture of how a SQL statement executes together.  F...