how to improve query performance

The so-called partition to improve performance is to narrow the scan range during table access, with a very small cost, reduce I/O operations, and achieve higher performance. The global index and Local index created on the partition table are both

ReprintedBytes IndexYou can use indexes to quickly access specific information in database tables. An index is a structure that sorts the values of one or more columns in a database table (for example, the last name (lname) column of the employee

Recently, a friend of mine told me that the execution of many stored procedures in his database has timed out. let me show him why. I saw that many temporary tables and variable tables were used in his stored procedures. so I told him that I was too

1. char () is a fixed-length field. For example, char (20) is saved to Microsoft for nine characters. Each storage can contain only 20 characters, followed by spaces, if you are not sure about the number of data, it will be a waste of space.Varchar (

　　[It168 technical documentation] 　　1. Batch modification and Deletion In hibernate 2, if you want to modify or delete any data, you must first query the data to be modified or deleted, then perform operations on the data. There is no problem in

The query language of ejb3 is similar to the intermediate and Object-Oriented Query Language of SQL. It can be compiled into SQL statements that are acceptable to different underlying databases, thus shielding the differences between different

Indexes can significantly improve query performance. Consider the query types used in your application so that you can define related indexes. Once the index definition is complete, it is very easy to create them in mongodb. Mongodb indexes are

In the process of expanding the size of Web websites from small to large, the database access pressure is constantly increasing, and the database architecture needs to be dynamically expanded, the database expansion process consists of the following

1 Overview A recent blog on MySQL handlersocket attracted a lot of attention, and even the MySQL performance blog also had a performance evaluation on handlersocket. This blog claims that for a MySQL server with a CPU bound instead of an I/O bound

What is the principle of database indexing? The management of the MIS system for small and medium-sized enterprises is basically composed of two parts: one is the visual operation at the front end, and the other is the database management at the

What should I do if SQL server needs to store 10 million pieces of data? The company has a large business system with a large amount of data. Each of the major items of data exceeds 10 million records. I have been using sqlserver for a long time. I

Sysbase is a pioneer in column-based databases. Sysbase IQ 15 is the latest column-based database of Sybase. It has powerful functions, including fast data loading, ultra-high-speed analysis performance, powerful intelligent business analysis, and

The B + tree is a classic data structure generated by the combination of the Balance Tree and the binary search tree. It is a balanced search tree designed for disks or other direct access devices, in the B + tree, all record nodes store the key

Rollup and cube, oralcerollup of Oralce advanced SQLIn oracle SQL query, oracle provides some advanced functions to simplify SQL query statements and improve query performance. The following describes the usage and difference of rollup and cube.1.

Database usage-oracle bitmap index,-oracle bitmap Index Currently, a large number of indexes are mainly B * Tree indexes. The index structure stores the rowids of key values and key values, which correspond one to one. Bitmap indexes are mainly

Index Problems I. Overview You can use indexes to quickly access specific information in database tables. An index is a structure that sorts the values of one or more columns in a database table.Indexes provide pointers to the data values of the

Sort attribute members by secondary attributes : In Lesson 3rd, you learned how to sort attribute members by their names or key values. You also learned how to use the composite member key to influence attribute members and sort order. For more

1. Vertical table sharding Vertical table sharding refers to splitting a table with 20 columns into two tables, one table with 10 columns and one table with 11 columns. This reduces the capacity of a single table, it can improve the query

I talked about database sharding in the previous article. 1. Vertical table shardingVertical table sharding refers to splitting a table with 20 columns into two tables, one table with 10 columns and one table with 11 columns. This reduces the

You can optimize the queries used to improve the performance of SQL Server compact 3.5 applications. The following sections describe how to optimize query performance.Optimize Indexes Creating useful indexes is one of the most important ways to