sql temp table performance

Label:In the original: Toward Dba[mssql Article] high-efficiency stored procedures for large tables "principle" with the worst performance SQL statement evolutionary process GuestThe results of the test are here to explain the principles of this articleDesign backgroundDue to historical reasons, the online library environment data volume and its huge, many tens above even billions of tables. The goal is to

In SQL query in order to improve query efficiency, we often take some measures to SQL optimization of query statements, the following summarizes some of the methods, there is a need to reference. In the optimization experience of a carrier has encountered a more interesting SQL, as follows: 1 The initial SQL execution

Label:In SQL Server, COUNT (*) or COUNT (1) or count ([column]) may be the most commonly used aggregate function. A lot of people actually have a clear distinction between the three. This article will describe the roles, relationships, and principles behind the three. As always, I often see some so-called optimizations that don't use COUNT (*) instead of count (1), which can improve performance, given the r

Original: SQL query performance analysisOriginal source: http://blog.csdn.net/dba_huangzj/article/details/7623926The performance of SQL query directly affects the value of the whole database, which must be treated solemnly.SQL Server provides a variety of tools, and here's a simple introduction:First, the

The WITHAS phrase, also called subqueryfactoring, allows you to do a lot of things and define an SQL segment, which will be used by the entire SQL statement. The with as phrase, also known AS subquery factoring, allows you to do a lot of things and define an SQL segment, which will be used by the entire SQL statement.

Test sql: Copy Code code as follows: SET STATISTICS IO on SET STATISTICS time on SELECT COUNT (1) From Dbo.tbtext A INNER LOOP JOIN Dbo.tbtext b On a.id = b.id option (MAXDOP 1) SET STATISTICS IO off SET STATISTICS Time off Table structure: Copy Code code as follows: CREATE TABLE [dbo]. [Tbtext] ( [ID] [int]

Original address: http://www.cnblogs.com/qiusnay/archive/2010/03/15/1686500.html 3. Performance and efficiency 5.3. Fixed length and variable length table A data table containing any varchar, text, and other variable-length fields, which is a variable-length table, whereas a fixed-length

In Oracle 10 Gb, there is a single-Table query SQL statement, which does not have a where clause, but simply calculates the maximum and minimum values of a column at the same time.According to our understanding, it should undergo a full index scan, but it does. The data size of a single table is a little large, and the composition is a little complicated. There a

First of all, let's look at one of the steps here that translates into banner, which requires pivot, step-by-step Then look at the overall query results for the two query methods after the main table join So take a look at the latter query method is also through the industry after the conversion to do the join execution plan, you can see only the Word table for a search (this is the index seek, but th

Comparison of paging stored procedures and performance of five types of SQL Server, SQL stored procedures In SQL Server database operations, we often use stored procedures to implement paging processing of the queried data to facilitate browsing by viewers. This article summarizes the five paging stored procedures for

you create a table variable, you cannot make DDL statements for it, which includes the CREATE INDEX statement. You can, however, create an index for a table variable when it is defined, such as the following statement.This statement will create a table variable that has a clustered index. Because the primary key has a corresponding clustered index, a system-name

Label:Index, Index!!! Jianjian index for frequently queried words!! However, you cannot build indexes too much. Changes to table records, such as insert and delete, can cause indexes to reflow, increasing the burden on the database.Optimize your goals 1. Reduce the number of IOIo is always the most vulnerable to the database, which is determined by the responsibility of the database, most of the database operations more than 90% of the time is occupie

session. After the session is disconnected, the table is deleted. If the # employees global temporary table is created, any user in the database can use the table. If the table is not used by other users after you create it, delete it when you disconnect it. If another user is using the

AI-like 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 t

exist and not exist instead of in and not.You can use table links instead of exist. Having can be replaced by where, if not replaced, can be handled in two steps.ExampleSELECT * from ORDERS WHERE customer_name not in (SELECT customer_name from CUSTOMER)OptimizationSELECT * from ORDERS WHERE customer_name not exist (select Customer_name from CUSTOMER)7.2 Do not declare numbers in character format, you want to declare character values in numeric form

Tags: des style blog http color io os using AR2014-08-22 BaoxinjianI. Summary 1. Partition table:As the table continues to grow, it is more difficult to maintain the new record's increase, find, delete, and so on (DML). For a very large table in a database, you can simplify the management of the database by dividing its data into several small tables. For each simplified small

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 tableAn important way to simplify

statements first, converting lowercase letters to uppercase and then executing (20) Use the connector "+" connection string sparingly in Java code! (21) Avoid using not on indexed columns usually (22) Avoid using calculations on indexed columns (23) Replace > with >= (24) Replace or with union (for indexed columns) (25) Replace or with in (26) Avoid using is null and is not NULL on an indexed column (27) Always use the first column of an index (28) Replace union with

Welcome to the Linux community forum and interact with 2 million technical staff. Many people use the database design paradigm as the database table structure design Bible. They think that as long as they are designed according to the needs of this paradigm, the table structure can be optimized to ensure excellent performance and meet scalability requirements. It

directory: MYLOG.000001: Log backup file. If you want to view the information in this log file, we can use the Mysqlbinlog program to view the Mysqlbinlog program stored in the MySQL Bin directory ("C:\Program files\mysql\mysql Server 5.6\bin ”）。 Execute SQL statement UPDATE emp Set ename= ' Zouqj ' where empno=100003; Start-run--cmd,mysqlbinlog backup file path C:\Program files\mysql\mysql Server 5.6\bin>mysqlbinlog G:\Database\mysqlbinlog\mylog.000