Sql In Efficiency

The greatest fascination with large data is the new business value that comes from technical analysis and excavation. SQL on Hadoop is a critical direction. CSDN Cloud specifically invited Liang to write this article, to the 7 of the latest technology to do in-depth elaboration. The article is longer, but I believe there must be a harvest. December 5, 2013-6th, "application-driven architecture and technology" as the theme of the seventh session of China Large Data technology conference (DA data Marvell Conference 2013,BDTC 2013) before the meeting, ...

Presumably every DBA would like to challenge the data import time, the shorter the work efficiency, the more sufficient to prove their strength. In the actual work sometimes need to import a large amount of data into the database, and then for various program calculation, this article will recommend a challenge 4 seconds limit to let millions data into SQL Server experiment case. This experiment will use the 5 method to complete this process, and detailed records of the various methods of time spent. The tools used are Visual Studio 2008 and SQL Server 2000, SQL S ...

Setting filter conditions to improve indexing efficiency good indexes are key to SQL Server database performance, but efficient indexes are carefully designed. As we all know, a primary key is a unique identifier for a data object, and if there is no clustered index in the datasheet, the SQL Server database will create a clustered index (Clustered index) for the primary key by default in order to maintain the uniqueness of the key. Unless the user specifically specifies that the index should be created as a nonclustered index (non-clustered index). There is no doubt that we ...

A few suggestions to improve SQL execution efficiency: Try not to include subqueries in where; queries about time, try not to write: where To_char (dif_date, ' yyyy ') =to_char (' 2007-07-01 ', ' yyyy '); In the filter condition, the condition in which the maximum number of records can be filtered must be placed at the end of the WHERE clause, and the last table (underlying table, driving table) in the FROM clause will be first ...

We want to do not only write SQL, but also to do a good performance of the SQL, the following for the author to learn, extract, and summarized part of the information to share with you! (1) Select the most efficient table name order (valid only in the Rule-based optimizer): The ORACLE parser processes the table names in the FROM clause in Right-to-left order, and the last table in the FROM clause (the underlying table driving tables) is processed first, In the case where multiple tables are included in the FROM clause, you must select the table with the least number of records as the underlying table. If...

The logical design of database is a very broad problem. In this paper, the main key design of the table is discussed in the design of MS SQL Server, and the corresponding solutions are given. Primary key design status and problems about database table primary key design, in general, based on business requirements, based on business logic, the formation of primary key. For example, when sales to record sales, generally need two tables, one is the summary description of the sales list, records such as sales number, the total amount of a class of cases, and the other table record of each commodity ...

Data such as video, music and text have been expanding indefinitely, driven by surging networking devices and ubiquitous Internet connectivity. A recent report by Gartner, a research institute, says "Big data" will become a new conventional industry in the next 10 years. At present, including Google, IBM, Microsoft, EMC, Hewlett-Packard and many other giants, has begun to layout large data, in the coming Big Data era to do a good job in the foreshadowing. How to use massive data to bring value to the enterprise is the main focus of Microsoft's current, but also the core elements of large data. Through data Mining ...

Intermediary transaction http://www.aliyun.com/zixun/aggregation/6858.html ">seo diagnose Taobao guest cloud host technology Hall before writing a paging stored procedure, we first create a test table for the database. This test shows that there are 3 fields, called Order, which are or_id,orname,datesta; The following creates a table script: CREATE TABLE [dbo]. [Orders ...]

Intermediary transaction http://www.aliyun.com/zixun/aggregation/6858.html ">seo diagnose Taobao guest cloud host technology Hall in the consideration of a website if the host million or tens of millions of PV, We tend to think in two directions instinctively: static and distributed. Of course, for Sina and other portal types of Web sites, static + read and write separation and distribution, can solve most of the problems. But we are facing more, may be large data + high and ...

MySQL database sql statement commonly used optimization methods 1. Query optimization, should try to avoid full table scan, should first consider where and order by the columns involved in the establishment of the index. 2. Should be avoided in the where clause on the field null value judgment, otherwise it will cause the engine to abandon the use of indexes and full table scan, such as: select id from t where num is null You can set the default value of num 0, to ensure that Num column table does not null value ...