query optimization in dbms

in the flow log table. it is estimated that it may reach 40 million records per day. using a table per day is also very large. I have read it. the MYD file size is more than 8 GB. When we query the log records in the management system, we need to perform conditional queries on several fields, and several fields have a length of 256. in the 8G table, we need to query a string. if the string cannot be found,

largest number of records in the flow log table. it is estimated that it may reach 40 million records per day. using a table per day is also very large. I have read it. the MYD file size is more than 8 GB. When we query the log records in the management system, we need to perform conditional queries on several fields, and several fields have a length of 256. in the 8G table, we need to query a string. if t

When querying database records using SQL statements, there are many different ways to query the same content.Still, although you can get the same results using a variety of methods, if you use a different approach, the execution benefits are quite different. Therefore, we have to consider carefully, if you want to query the same results, which statement to use, the implementation of the benefit is better.Th

2005 provides the INCLUDE parameter in the Create Index statement, add other fields of the data table unrelated to the key-value column to the leaf layer of the non-clustered index to expand the non-clustered index function. However, these fields are not sorted and other additional maintenance actions are not performed. When querying, you can obtain all relevant data only by reading the index structure, without accessing the table or clustered index data, thus reducing disk I/O operations, redu

Slow Query Optimization of MySQL is a common topic. This article describes the actual problems encountered in the production database and provides examples. Enable slow query supportFirst, activate the slow query log, modify the my. CNF configuration file, and add the following options:Log-Slow-queries = slow. LogLong_

ORACLE query optimization and gather_plan_statistics hint, oracledbmsgather Query Optimization Methods and gather_plan_statistics hint:After 10 Gb, we can use the gather_plan_statistics prompt to learn more about SQL Execution statistics. The usage is as follows: If the statistics_level parameter is set to ALL, or the

will use the memory of the sort_area_size. The optimization of this memory is also very important.4. The Order by statement is added to the index column, preferably the primary key PK. SELECT Dept_code from DEPT ORDER by Dept_type (inefficient) 5. Avoid using resource-intensive operations:SQL statements with distinct,union,minus,intersect start the SQL engine to perform the resource-intensive sorting (sort) function. Distinct requires a sort operati

database application development tools and supports Java™SQL pl and PL/SQL routines, XML editor, and other development methods. It can also be integrated with IBM's query optimization tools to Optimize Query performance. Monitoring and Management of database health and availability plan jobs. Data Studio 3.1.1 provides a Web-based monitoring tool for health an

The optimization scheme of SQL Server Multi-table query is the main content of this article, we give the optimization scheme and specific optimization examples, then let us take a look at this part of the content. 1. Execution path This feature of Oracle greatly improves the performance of SQL and saves memory usage:

. In the 8g table, we need to query a string. If the string cannot be found, it must be retrieved from the beginning, and the speed is too slow. The customer also needs to set conditions for query in several fields. In this way, the system availability is very low because it is usually 20 or 30 minutes long. The method I used is mainly for testing. I also read the JAVA code and use Log4j and Perf4j logs to

compilation, only 0.7 seconds to get the results. So how do you precompile, or use an existing execution plan?SQL Server has an optimization algorithm that holds the execution plan for the previous execution of the SQL statement, and all execution plans are stored in the Sys.syscacheobjects table, and if the current SQL statement matches in the cache table, then it executes the execution plan that matches to it and no longer compiles. So the solution

1. UseProgramTo minimize the number of accesses to the database. By searching for parameters, You can minimize the number of rows accessed to the table and the result set, thus reducing the network burden; separate operations should be processed separately to improve the response speed each time. When using SQL in the data window, try to place the indexes in the first column selected;AlgorithmThe structure should be as simple as possible; During the query