sql performance counters

Performance Comparison Between ISNULL and COALESCE in the paging mode of SQL Server, isnullcoalesce Preface In the previous section, we explained the data type and several notes in the string. In this section, we will continue to talk about the number of string lines, other content and interspersed content, short content, and in-depth explanation. (For details, see "Data Types in

where should we start? The root cause is generally the database design and access to its query. In this month's column, I will talk about four technologies that can be used to improve the performance of SQL Server? Or improve the scalability of the application. I will carefully describe the use of LEFT JOIN and CROSS JOIN and the retrieval of IDENTITY values. Remember, there is no magic solution at all. Ad

the problem. So, where do we start? The root cause is usually the database design and the query that accesses it. In this month's column, I'll talk about four technologies that can be used to improve SQL Server based? The performance of the application or improve its scalability. I will carefully describe the use of the left join, the CROSS join, and the retrieval of the IDENTITY value. Remember, there is

SQL Server performance optimization -- wait -- SLEEP_BPROOL_FLUSHPreface: There is a database for historical archiving (referred to as the historical database). After a certain amount of time, the data file has reached more than 700 GB, and it was decided that some data does not need to be retained, this part of data is truncate and more than 600 GB of space is available. That is to say, after the contracti

can ensure that the database will faint. In addition, execution plans can be reused, and the simpler SQL statements are more likely to be reused. Complex SQL statements have to be re-parsed as long as one character changes, and then the bulk of the garbage is stuck in memory. It is conceivable how inefficient the database will be. 4. Staging intermediate results using temporary table An important way to si

things, after all, than the person's resolution is worse, if people are looking dizzy, I can ensure that the database will faint. In addition, execution plans can be reused, and the simpler SQL statements are more likely to be reused. Complex SQL statements have to be re-parsed as long as one character changes, and then the bulk of the garbage is stuck in memory. It is conceivable how inefficient the datab

The Oracle tutorial is: Oracle-based high-performance dynamic SQL Program Development. Abstract: This article summarizes the development of dynamic SQL programs and provides several development skills based on the actual development experience of the author. Keywords: dynamic SQL, PL/

Oracle SQL Performance Optimization: 2. When a user establishes a connection with the database, an operation request is sent to the database, that is to say, send the previous SQL statement (or several or one PL/SQL package) to the database. After Oracle receives the SQL sta

Setting the SQL _trace parameter to true will track the entire instance, including all processes: User processes and background processes, which may cause serious performance problems. Be cautious in the production environment. Setting the SQL _trace parameter to true will track the entire instance, including all processes: User processes and background processes

Unlike other SQL Server databases, tempdb stops at SQL Server and automatically drops and re-create upon restart. by default, a new 8 MB (MDF file: 8 MB; LDF file: 1 MB, autogtouth is set to 10%) recovery model is a simple tempdb database. After the tempdb database is created, DBA can create data objects, temporary tables, temporary stored procedures, and table variables in other databases and add them t

I. Question proposal At the early stage of application system development, due to the relatively small amount of data in the development database, the performance of SQL statement writing is not good for querying SQL statements and writing complex views, however, after the application system is submitted to the actual application, as the data in the database incr

[Author: Shi XiaoYu] I. Question proposalAt the early stage of application system development, due to the relatively small amount of data in the development database, the performance of SQL statement writing is not good for querying SQL statements and writing complex views, however, after the application system is submitted to the actual application, as the data

become a problem, it is necessary to first understand what sleep_bpool_flush this waiting state is. In Microsoft's official note: https://technet.microsoft.com/zh-cn/library/ms179984 (v=sql.105). aspx, with a simple description: When checkpoints abort new I/O to prevent disk subsystem flooding Appears at the time of publication. Obviously, this explanation is inadequate. So I turned over the foreign Daniel Blog and other books, summarized as follows:

statements have to be re-parsed as long as one character changes, and then the bulk of the garbage is stuck in memory. It is conceivable how inefficient the database will be. 4. Staging intermediate results using temporary tables An important way to simplify SQL statements is to use temporary tables to stage intermediate results, but the benefits of temporary tables are much more than that, temporary tables are temporarily present in tempdb, and the

After a period of research, we started to optimize the performance this week. Before optimization, I will summarize some of the information I have investigated. 1. Background This is a system developed in the past 03 years. NET 1.1 + SQL Server 2000, the operating system uses Windows2003. After so many years of use, the operating system was upgraded (from Windows2000 to 2003 at that time) and system mainten

Yesterday I introduced to you how to find bad code, how to gracefully implement an application of the monitoring program. Of course, after discovering the bad code, we still have to find a way to get rid of it, perhaps it will be very stubborn. Tell me today. A very important part of performance optimization: SQL optimization What I'm going to say today is not how to write good,

execution. Then, there are operators that require additional memory space to store row data, and the amount of memory required by such operators is usually proportional to the number of rows of data processed. This can cause memory to not be applied if any of the following conditions affect execution performance A, if the server is performing other similar memory consumption of large queries, resulting in insufficient system memory, the current query

types of index performance is not the same, should be used as far as possible first high-performanceThe 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 Username= ' Zhang San ' and age>=21(efficient) Select ... from TableName where age>=21 and Username= ' Zhang San 'Second,

ORACLE stores the executed SQL statements in the shared buffer pool, which can be shared by all database users. When you execute an SQL statement (sometimes called a cursor), if it is exactly the same as the previously executed statement,ORACLE can quickly obtain parsed statements and the best execution path. This function greatly improves SQL Execution

Tags: time access connection between directory conditions cannot loop archIt is often asked whether the conditional writing order of the WHERE clause in Oracle has an impact on SQL performance, and my intuition is not affected, because if this order has an impact, Oracle should be able to automatically optimize it early, But there has been no conclusive evidence of this. articles found on the Internet are g