1. What is a database? acid refers to the four features of the Office in the database management system 1) atomicity 2) consistency 3) Isolation 4) Persistence & nbsp; relational database, based on relational algebra, database form is a table, data can be accessed or re-convened in different ways.   2. Relational algebra (simply an abstract query) Mathematically speaking, relational algebra is the remainder of the Boolean algebra that supports the unary operation called inverse from the database level, is a set of relationships that are closed to arithmetic NOTE: Although SQL's query statements are loosely based on relational algebra, many useful theories about relational algebra do not work in SQL counterparts. SELECT * * * * //projection from *** //Cartesian product where *** // Select union //set \ Difference set ... 3. Query optimization This blog focuses on "query rewrite rules" and " Query algorithm Optimization ", from the perspective of optimized content, query optimization is also divided into algebraic optimization and non-algebraic optimization, or called logical optimization and physical optimization 4. Database tuning and Query statement tuning Database tuning can make database applications run faster Its purpose is to make the database by a higher throughput and shorter response time, the object being tuned is the entire database management system overall Query statement tuning objects is a query statement 5. Key technologies in five phases of database tuning 1. Application estimation Application usage, data volume, database pressure, peak pressure, etc. make an estimate 2. System Selection Strategy Determine what database can use application requirements 3. Design of the data model   1) e-r model design 2) Data logic distribution Strategy 3) Data physical Storage Policy 4) index, the appropriate index on the object to be queried frequently, so that the positive effect of the index is greater than the negative (index maintenance is consumed) 4.SQL design 5. System monitoring and Analysis
MySQL query optimization from getting started to running (a) database and relational algebra
