db2 query optimization

string, if not found, that must be traced back to the tail, speed is too slow to bear. Customers also have several fields set the criteria together to query, so basically twenty or thirty minutes will not come out, system availability is very poor. My approach is to test the main, while looking at Java code, through log4j and perf4j logs, look at the time each SQL statement used, look for performance bottlenecks, and then targeted for

Speaking of mysql, we immediately think of its small size, fast speed, and open source features, so it is widely used. Today, we will summarize the two most frequent mysql operations: insert and query, and the optimization methods. Insert: I. Text Import Using load data infile to download DATA from text is 20 times faster than using the insert statement. Example: Load data local infile 'C:/Users/DELL/Deskt

query tree 22212.7 cut off a branch 22312.8 field List value de-weight 224The 13th chapter of the Application case Realization 22713.1 Extracting elements from a string from a fixed position 22713.2 Searching for alpha-numeric mixed strings 23013.3 grading results and converting to columns 23013.4 Importance of building the underlying data 23413.5 Returning data from different columns based on incoming criteria 23513.6 splitting a string to connect 2

can greatly optimize the query speed, basically can be completed within dozens of milliseconds. The restriction is only used to explicitly know the ID, but when the table is established, the Basic ID field is added, which brings a lot of traversal to the paging query.There is another way to do this:selectfromwhereid1000001limit100;Of course, you can also use in the way to query, this method is often used i

Query optimization Technology of databaseQuery optimization Technology of databaseDatabase system is the core of MIS, and online transaction processing (OLTP) and online analytical Processing (OLAP) based on database is one of the most important computer applications in banks, enterprises and government departments. From the application examples of most systems,

Php+mysql Query Optimization Simple instance This article mainly introduces the simple example of Php+mysql query optimization, analyzes the techniques of SQL statement optimization query in Php+mysql program design, and has some

normalCreate an indexALTER TABLE tabname Add index idxname (column)ALTER TABLE tabname add unique (column)ALTER TABLE TabName add primary key (column)Create INDEX Idxname on tabname (column)Create unique index idxname on tabname (name)Delete IndexDrop Index idxname on tabnameALTER TABLE tabname DROP INDEX IdxnameMySQL Slow query" %slow% " ; 2 | more than 2 seconds are defined as slow queries. | Slow_query_log | OFF | slow

Label:MySQL Database optimization pt-query-digest use I. Introduction of PT-QUERY-DIGEST Tools Pt-query-digest is a tool for analyzing MySQL slow query, which can analyze Binlog, general log, Slowlog, or through show Processlist or the MySQL protocol data captured by Tcpdump

index! The title of this article is: "Query optimization and pagination algorithm scheme." The author only so that "query optimization" and "pagination algorithm" These two links are not very big topic together, because both need a very important thing--clustered index. As we mentioned earlier in the discussion, clust

Tags: multiple table association between key words left JOIN best like inconsistent ATI driverTransferred from: http://blog.csdn.net/kevinlifeng/article/details/43233227 Statement is their own study is not original, hope everyone support the original. SQL statement optimization and indexing 1.Innerjoin and left connection, right connection, sub query A. Inner joins are also called equivalent connections, le

Tags: suitable for minimum hit use where to go Scale index desc execution planFirst, Introduction1. What is an index?General application system, reading and writing ratio of about 10:1, and the insertion operation and the general update operation rarely appear performance problems, in the production environment, we encounter the most, is also the most prone to problems, or some complex query operations, so the opt