how to improve query performance

MySQL has not provided such complex functions as function indexing since ancient times. So how can this function be implemented in MySQL? Let's take a look at the concept of function indexing. Function indexes, also known as Expression indexes, are

Mysql Performance Optimization 1. optimize table 2. analyze table 3. try to declare the column as NOT NULL 4. Mysql only uses the prefix index to avoid creating an index on an existing index prefix.For example, do not create an index (a) on index

Understanding MySQL-index and optimization is at the beginning: indexes have a crucial impact on the query speed. understanding indexes is also the starting point for database performance tuning. Consider the following: assume that a table in the

This article mainly introduces the open-source MySQL efficient data warehouse solution: Infobright details. This article describes the features of Infobright, the value of Infobright, the applicable scenarios of Infobright, and the comparison with

Mysql master-slave replication and lvs43; keepalived achieves load high availability directory 1. preface 42. principle 421. Overview 422. Working principle 423. actual action 43. solution 431. environment 43. mysql master-slave replication and lvs +

Explanation of the usage of explain in mysql MySQLexplain BitsCN.com The explanation of mysql explain is clear.Of With the help of explain, you will know when to add an index to the table to use the index to search for records so that select can run

7.2.1EXPLAIN syntax (obtain SELECT-related information) The EXPLAINtbl_name or: EXPLAINSELECTselect_optionsEXPLAIN statement can be used as a synonym for DESCRIBE, or used to obtain information about the SELECT statement to be executed by MySQL.

This article mainly introduces what is DB2 database partition and why database partition is used. The following uses Balanced Warehouse E7100 as an example to introduce the basic methods and application practices of database partition management. DB2

Materialized views are similar to indexes in many aspects: materialized views are used to improve query performance, while materialized views are transparent to applications, adding or deleting materialized views does not affect the correctness and

Database partitioning is one of the key functions required by each database. Almost all Oracle databases use the Partition Function to improve query performance. The Oracle 11g Partition Function simplifies the daily management and maintenance of

This article describes the concept of a one-level, two-level cache in Hibernate and how to use it.First, the outline2. What is a first-level cache3. First-level cache example Display4. Level Two cache and sample display5. SummarySecond, what is a

The EXPLAINtbl_name or: EXPLAINSELECTselect_optionsEXPLAIN statement can be used as a synonym for DESCRIBE. It can also be used to obtain information about the SELECT statement to be executed by MySQL. The syntax of EXPLAINtbl_name is the same as

Hibernate hql Query:The criteria query encapsulates the query criteria in an object-oriented manner, but HQL (Hibernate query lanaguage) queries provide richer and more flexible query features. As a result, Hibernate makes the HQL query the official

Oracle integrity constraints are used to enhance data integrity. Oracle provides five integrity constraints: Check not null Unique Primary Foreign key integrity constraints are a rule, it does not occupy any database space. Integrity constraints

Database usage-create and classify oracle Indexes Database usage-create and classify oracle Indexes An index is an optional data structure in a database. It is usually related to tables or clusters. You can create an index on a column or series of

Rollup and cube 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. rollupRollup

I. general usage of Materialized views are a special physical table. Materialized views are relative to normal views. A common view is a virtual table, which has many application limitations. Oracle converts any View query to a view SQL statement

MongoDB is a popular non-relational database. As a document-based database, in addition to the flexible data structure with or without schema, MongoDB supports complex and rich query functions, and also comes with a powerful sharding function. To

Partition Table in oraclePartition tables in oracle are frequently used in the system and frequently appear in some systems with large data volumes. When talking about partition tables, we must first understand what partitions are. In fact, the

By default, the tempdb database is placed on the master device with a capacity of 2 MB, temporary databases are the most common databases used for sorting, creating temporary tables, and re-formatting. Therefore, tempdb optimization should be paid