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Many Programmers think that query optimization is a task of DBMS (Database tutorial Management System). It has little to do with the SQL statements compiled by the programmers. This is wrong. A good query plan can often increase the program

Recently, a friend asked me that it was very slow for him to delete millions or tens of millions of data from SQLSERVER. He analyzed the problem and gave some comments as follows, it may be useful to many people.If your hard disk space is small and

There are two types of repeated data: one is a completely repeated record, that is, the values of all fields are the same; the other is a record with some field values repeated. 1. Deleting completely duplicated records data is usually caused by the

File Cache, database cache, optimized SQL, data shunting, horizontal and vertical division of database tables, and optimized code structure! Summary 1. why do the following data inconsistencies occur when multiple users are locked for concurrent

Author: Ayouhttp: sudone.com the website is growing and stores more and more things. How to solve these problems has become a new challenge. It is not a good idea to completely store these files using a large hard disk, because the larger the data

Problem description: An exception occurs when the page data volume is large. Details: System. InvalidOperationException: the current state of the object invalidates the operation.   Cause:This exception occurs because of the last abnormal

In the following article, I will take the "office automation" system as an example to explore how to implement rapid data extraction and data paging IN THE MSSQLSERVER database with 10 million pieces of data. In the following article, I will take

I. Some Influencing Factors · Compression format and compression ratio When importing raster data, you can select different compression formats and compression ratios based on your needs. Common examples include compression, lz77, JPEG, and MPEG-4,

// Chinese word segmentation is the foundation of the Chinese search engine. It is mainly used in information retrieval, information mining, Chinese and foreign translation, Chinese proofreading, automatic clustering, automatic classification, and

The original question is as follows: Assume that a log of 100 GB exists on the disk, and each log occupies no more than bytes. Now N logs are randomly selected from the log, make sure that the probability of selecting each log is the same. Solution 1

A small website, such as a personal website, can be implemented using the simplest HTML static page. With some images for beautification, all the pages are stored in a directory, such websites have very simple requirements on system architecture and

Recently, I 've been reading some things about Linux C Server programming, and it involves a lot of connection processing problems. We know that in Linux, we generally use the TCP/IP protocol to write simple C/S model code and often use the select ()

Java. util. bitset can be stored by bit.One byte occupies 8 bits in the computer. Data in Java is stored at least by byte,For example, an int occupies 4 bytes.If you encounter a large amount of data, it will inevitably require a large storage space

Cphpc++ multi-Dimension query large files There is a large file of more than 20 g inside a row of (CSV format, comma-separated type of the kind) is the order information is the main user ID merchant ID and the order ID must be required to find

Address: http://www.cnblogs.com/kivenhou/archive/2010/10/06/1844856.html Note:1. Try to avoid null value determination on the field in the WHERE clause. Otherwise, the engine will discard the index and perform full table scanning, for example:Select

20-million data records Instant change of table name Instantly changed field name Moving fields is very slow for 10 minutes. It is better to make a view to rearrange the positions. Adding an index for 1 minute, but if the table is very busy, it

Note:1. Try to avoid null value determination on the field in the where clause. Otherwise, the engine will discard the index and perform full table scanning, for example:Select id from t where num is nullYou can set the default value 0 on num to

The maximum heap is the big root heap -- the first n small and the smallest heap is the small root heap -- the first n Large, for example, the first n small, for the current element, compared with the heap top element (that is, the maximum heap

With the popularity of Ajax, Ajax is now widely used in projects. It can be said that AJAX is widely used. It is difficult to manage because of a large number of Ajax requests. As a result, we often send requests in a unified manner, with a unique

In the non-grid method, ttttttttt draws discrete points. If there are many points, they cannot be represented by small balls. In my test, if the number of small balls exceeds one hundred, the speed is too slow to bear. The solution is to use the dot