sql performance counters

used; the third SQL uses place, all referenced columns are included in the composite index, which forms an index overwrite, so it is very fast. 　 4. Combined indexes on date, place, and amountSelect count (*) from record where date> '20160301' and date Select date, sum (amount) from record group by date (11 seconds)Select count (*) from record where date> '2013' and place in ('bj ', 'sh') ( Analysis:This is a reasonable composite index. It uses date

As a code generator and ORM tool, linq to SQL automatically performs many tasks for us, which can easily cause us to doubt its performance. However, there are also several tests that show that the performance of linq to SQL can be improved to 93% of the performance of ado.ne

I have been looking for some authoritative references on SQL statement performance debugging, but I may not be able to do a good job of debugging. I believe that the experience gained in practice is the most precious, and book knowledge is just a guide. This article comes from "Inside Microsoft SQL Server 2008", although experienced experts make bricks. This sec

report server cache per second. Memory Cache Hits/sec The number of times per second that the report was retrieved from the memory cache. The memory cache is part of the report services cache, which stores reports that are displayed in memory or in temporary files. This will provide the best performance for the request because there is no need to process it. When the memory cache is available, the report server cannot query

: ALTERDATABASEMyDatabaseNameSETOFFLINE; Next, copy the data file to the new location. Use replication instead of moving. You can perform quick rollback in case of any errors. Otherwise, you must perform restoration ). Then, use the following code to notify SQL Server of the new location of each file ALTERDATABASEMyDatabaseName MODIFYFILE (NAME=N'LogicalFileName', FILENAME=N'pathname\filename'); After all files are physically co

Oracle Performance Analysis 1: Enabling SQL tracking and obtaining trace files When there is an issue with Oracle query efficiency, we often need to understand the problem so that we can provide a solution to the problem. Oracle provides the trace information for SQL Execution, including the text information of SQL sta

; (efficient) Select ... from [dept] where [sal]>25000/12; 10, different types of index performance is not the same, should be used as far as possible first high-performance The index lookup efficiency of a numeric type is higher than the string type, and the index of fixed-length string char, nchar is higher than the variable-length string varchar, nvarchar. (inefficient) Select ... from tableName where Us

gender from users where gender = 'male ', this query is very efficient and the index ix_gender has been successfully used. However, we write less SQL statements like this. For more SQL statements, we can write such as select userid, username, phone, email from users where gender = 'male' then you can look at the query plan and try to use the index ix_gender. Instead, you perform a clustered index scan or t

SQL Server Full-text indexing performance has been not too good, listen to colleagues today to share, found a skill, go back to try, found that can obviously improve the performance of full-text indexing, generally can improve twice times + Original SQL statement: SELECT * from Table1 where contants (*, ' test ') 　

Next, the index Optimization for MySQL database performance optimization, which isMySQL database performance optimization topicsThe fourth article in the series:MySQL database performance optimization-SQL Optimization Some people have reported that the previous articles are too theoretical and lack practical operation

This article is based on MySQL. Many content applies to other relational databases at the same time and requires some indexing knowledge. It focuses on how to optimize SQL to improve database performance. This article is based on MySQL. Many content applies to other relational databases at the same time and requires some indexing knowledge. It focuses on how to optimize

personally think that if most of the requests reach the second paradigm, the system will generate fewer columns and more tables, this reduces data redundancy and improves performance. 2, Reasonable redundancy It is almost impossible to design a system completely according to the standardization. Unless the system is very small, it is necessary to add redundancy in a planned manner after the standardization design. Redundancy can be a redundant databa

SQL Server Performance Tuning 3 (Index) MaintenanceHeat1 reviews Brook Stream GrassSQL Server Performance Tuning 3 (Index) MaintenanceObjectiveThe previous article describes how to improve the query performance of a database by building an index, which is really just the beginning. Subsequent to the lack of proper mai

factors, such as indexes, fragmentation, statistics, and locks, can affect performance, and optimization of these features may improve the execution efficiency of query statements. However, if the SQL statement is not properly written, it can significantly increase the avoidable overhead. Here are some things to keep in mind when writing SQL statements:

Original: SQL Drip 27-execution plan for performance analysisAlways want to find some of the authoritative reference for SQL statement performance debugging, but there is no reference may not be able to do the debugging work. I am convinced that the experience gained in practice is the most precious, and that book know