sql server performance tuning best practices

following is the optimization of the SQL statement in fact, SQL is not complex, but the data of these tables are slightly larger, but also nested inside more complex business logic, history after several rounds of "master" in the index of the whole side of the optimization, can also run normally but over time, the amount of data in the table is getting larger , boiled frog in warm water,

Tags: process optimizer consolidation requires merging auto overwrite session accessThe full execution order of the SELECT statement:The full execution order of the SQL SELECT statement: 1. The FROM clause assembles data from different data sources; 2. The WHERE clause filters the record rows based on the specified criteria, 3, the GROUP BY clause divides the data into multiple groupings, 4, uses the aggregation function for the calculation, 5, uses t

Label:Poptest is the only training institute for developing Test and development engineers in China, aiming at the ability of the trainees to be competent in automated testing, performance testing and testing tools development. In Poptest's LoadRunner training, in order to improve the performance of students experience, add a lot of server optimization knowledge,

Yesterday's SQL Server query performance optimization-index creation principle (I) mainly introduced the principle. today are some of the main principles and checks the created indexes. Iii. indexing principles In general, building indexes depends on the data usage scenarios. In other words, which SQL statements are co

be sorted, or it can be added to a column (like joins or additions). Any non-indexed item in the ORDER BY statement, or a computed expression, will slow down the query. Double-check the order BY statement to find non-indexed items or expressions that degrade performance. The solution to this problem is to rewrite the order BY statement to use the index, or you can establish another index for the column you are using, and you should absolutely avoid u

= DB_ID(@DatabaseName) AND SPId -- SELECT @SQL EXEC(@SQL) A very similar to the SQL code above, an other code block can be used by using the coalesce as shown below DECLARE @DatabaseName nvarchar(50) SET @DatabaseName = N‘Works‘ DECLARE @SQL varchar(max) SELECT @SQL = COA

10.1 Order problems for connecting query tablesThe parser for SQL Server processes the table names in the FROM clause in a right-to-left order, so the table that is written in the FROM clause (the underlying table driving tables) will be processed first, and in the case of multiple tables in the FROM clause, the tables with the fewest number of record bars must be selected as the underlying table. When

. Room number andAcquisition Time>='2013-11-6 0:00:00' andAcquisition Time'2013-11-7 0:00:00') Workaround, create a memory table in SQL, first identify the part, and then use the first part of the results to query the final result. It can be checked in seconds. SET STATISTICSIo onDBCCDropcleanbuffers--Turn off cachingDBCCFreeproccache--Turn off cachingSELECTT.* frommeasure_heat TWHERECommunity number=' -' andAcquisition Time=( SELECT min(Acquisit

SQL Server backup and recovery practices I started to back up and restore the database because a project was completed right away. I checked several methods to achieve this. My goal is to back up the database on the server, so I found several methods for implementation, which are roughly divided: 1: Back up data us

--windows Machine NameSysprep.exe check general, and turn off the machine--Instance NameSELECT @ @SERVERNAME, serverproperty (' SERVERNAME ')If SERVERPROPERTY (' servername ') Begindeclare @server sysnameSet @server = @ @servernameexec sp_dropserver @server = @serverSet @server = Cast (serverproperty (' servername ') a

rownumObviously, this writing will result in reading the table first, then sorting, and then taking the first 5 records, the plan is as follows:If we write like this, the semantics are the same, but it saves a lot of reading and sorting costs:Select/*+ Index (T1,IDX1_T1) */* from T1 where rownumThe execution plan for this SQL is as follows:As you can see, the SQL does not follow the hint instructions and s

Label:ObjectiveIn the previous article, we analyzed how the query optimizer works, including: detailed operation steps of the query optimizer, analysis of filter conditions, optimization of index items, and other information.In this article we analyze the detection of several key indicator values in the course of our operation.These indicator values are analyzed to analyze the operation of the statement and to analyze how it is optimized.Through this article we can learn the

Read Catalogue Objective Technical preparation ObjectiveIn the previous article, we analyzed how the query optimizer works, including: detailed operation steps of the query optimizer, analysis of filter conditions, optimization of index items, and other information.In this article we analyze the detection of several key indicator values in the course of our operation.These indicator values are analyzed to analyze the operation of the statement and to analyze how it is optimized

When interviewing MySQL DBA or those planning to do MySQL performance optimization, my favorite question is: MySQL server in accordance with the default settings after installation, what should be done to adjust it? To my surprise, how many people can not give a reasonable answer to this question, and how many servers are running under the default settings. Although you can adjust the variables on many My

index is deleted. Doing so causes an unnecessary rebuild of the nonclustered index. The conversion of a table from a heap table to a clustered index table always results in the rebuilding of a nonclustered index, because the content of a nonclustered indexed bookmark changes from the row number to the key of the clustered index. Do Plan Your Index defragmenting and rebuilding Based upon Usage If an index is frequently scanned, the external fragmentation of the index is important, which can have

DISTINCTdatabase_id,object_idFrom Sys.dm_db_missing_index_details) as Ddmid on ddmid.database_id = ddios.database_idand ddmid.object_id = ddios.object_idWHERE Ddios.page_lock_wait_in_ms > 0 and object_name (ddios.[ OBJECT_ID]) like ' Pos_transmst 'ORDER by Ddios.page_lock_wait_count DESC;/*******************************************************************************************--page IO Latch Wait *******************************************************************************************/ SEL

By changing the vast majority of SQL queries into stored procedures, such operations can undoubtedly improve some of the performance. All operations using "SELECT * from XXX" are specific to the required fields. A query that uses joins to connect more than 2 large amounts of data, and queries that have little variation on the underlying datasheet, uses the view and indexes the view. The reason comes from th

"SQL Server 2005 Deadlock resolution Discovery" mentioned a while ago, serious deadlock, the average occurrence of a deadlock every day, in the resolution and processing of SQL server2005 deadlock in the search for a lot of information and think of a lot of ways, on why deadlocks and how less deadlock has a further understanding, Here to share with you:

, without being hindered by interaction. Like what: Use a specific report server as a front-end server to process all report creation requests, so that other servers are free to process interactive reports. Use one or more report servers to handle the production of ordered subscriptions or event-driven reports. General performance

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