query tuning in sql server

sname isn't null --use compound criteria to query ...... /* When using compound statements, you need to combine multiple conditional statements using logical operators and Or Not Each individual conditional statement can be enclosed with () parentheses */ Aggregate functions (for processing results of record data) --aggregate function (for processing results of record data) /* Aggregate functions are some of the column functions that have

Label:Original: SQL Server Tuning Series advanced (how the query optimizer runs)ObjectiveIn the previous articles, we introduced a series of basic descriptions of operators and the optimization methods and techniques for each operator. This includes a series of our common operators, including how to view execution plans, how several datasets are commonly used, ho

Many of my friends may be making mistakes in performance optimization as described below. If you have any need, please refer to the mistakes in SQL Server query performance optimization to get out of the index. Many of my friends may be making mistakes in performance optimization as described below. If you have any need, please refer to the misunderstanding of

Tags: Benefits Right click Access lib ORM tle blog together SDNReading Query plans:stairway to SQL Server Indexes level 9 by David Durant, 2011/10/05 Original link: http://www.sqlservercentral.com/articles/Stairway+Series/72441/ The Series This article is part of the ladder series: SQL

Label:As a DBA, troubleshooting SQL Server is one of our responsibilities, and a lot of people each month bring us a variety of performance issues that can't be explained but solved. I've heard many times that the performance problems of previous SQL Server are fine and within normal range, but now everything has chang

successful, D-recovey for MS SQL Server can sometimes read out the data in the MDF data file. Let's describe some of the data recovery features of D-recovey for MS SQL Server.Let's take a look at some of the database corruption scenarios:1, due to power outages and other causes of database query, this is a more common

It is understood that the vast majority of developers have a thorough understanding of indexing, limited to the fact that most daily work has no chance, and there is no need to care about or understand indexing, when a query is too slow, you can create an index based on the query conditions. When another query is slow, you can create an index, or directly send th

Often listen to the students of Oracle materialized view, one of the functions of materialized view is that you can implement query rewriting, it sounds like a tall feeling, SQL Server also has the function similar to Oracle materialized view, just called indexed view. To tell the truth, or materialized views sound more appropriate, compared to the normal view, m

It is understood that most developers have a smattering of understanding of the index, limited to most of the daily work no opportunity, what is not necessary to care about, understand the index, it is really a query too slow to find the query conditions to build an index on OK, which day again a query slow, and then establish an index is, Or simply send the enti

SQL Server 2016 improves the Query Optimizer The first two versions of SQL Server mainly improve performance by providing new features, while SQL Server 2016 mainly improves its existin

block according to the pointer on the index block, so that the IO traffic is much less. Second, index optimization technology Is there an index that must be retrieved quickly? The answer is yes. Sometimes it's better to use indexes than to index faster. For example, we want to retrieve all the records in the above table, if not indexed, need access to 8,000 x1000 bytes/8k = 1000 pages, if you use the index, first retrieves the index, accesses 8,000 x10 bytes/8k byte = 10 pages to obtain the ind

versioning) information, and so on. SQL Server allows users to create temporary tables for their own use, where the physical location of these temporary tables is tempdb. Note: Each time the SQL Server instance is restarted, the contents of the database are deleted and recreated as a copy of the model. Therefore, When

Myth 1. An index is established on a table and an indexed column is used at query time, and the index is bound to take effectFirst of all, it is wrong to make it clear that the SQL Server query optimizer is a cost-based optimizer that determines whether to use an index, what type of index to use, and which index to use

about what the database engine is doing. With the trace tool, we can monitor 180 events. In these events, we can view details of the user's login and lock activity through a special session ID (SPID). This data is generated through SQL Server Profiler, as well as a series of server-side stored procedures and. NET classes, and can provide you with the flexibility

Label:Original: 1th week how SQL Server executes a queryHello everyone, Welcome to the 1th week of SQL Server Performance Tuning training . Before we go into the tedious details of SQL Server performance tuning, I want to build th

There are many causes for slow query speed of SQL Server databases. The following are common causes: 1. No index or no index is used (this is the most common problem of slow query and is a defect in programming) 2. Low I/O throughput, resulting in a bottleneck effect. 3. the query