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Index maintenance is an important task in the daily maintenance of database. In fact, the index maintenance of SQL Server mainly focuses on the following three issues. Overindexing Insufficient index Index fragmentation rate This paper also introduces some practical daily maintenance methods and tools from these three perspectives. Overindexi ...

github synchronous update Blog Synchronization Updates Synchronized Updating of Brief Books Project address: Portal In normal development, the field names in our tables and the attribute names of the corresponding entity classes are not necessarily identical. Let's show how to resolve the conflict between the field names and the entity c ...

View the data type of the current database postgres=# \d pg_type ; Table "pg_catalog.pg_type" Column | Type | Modifiers ----------------+--------------+----------- typname | name | not null typnamespace | oid | not null ---- //Show all type types and corresponding storage types: postgres= ...

You should know that the biggest feature of mysql is master-slave replication compared with other databases, but the version before 5.7 only supports one master-slave replication at most. For some statistical classes, it needs to cross-database. This is a troublesome thing. In the past, only database middleware (mycat, etc.) can do this kind of ...

When a large system is set up, it will be found that many SQL operations overlap, and individual calculations are the same, for example, in a business system, how a single sheet is calculated.When these situations arise, using stored procedures is a great optimization. This series: demo download (1) MySQL Optimized Notes (1) - Basic op ...

Thing: Things are a logical set of operations in which the units that make up the set of operations either succeed or fail entirely In short, a set of operations either succeeds or fails; one thing has n components or n components succeed at the same time or n components fail at the same time. mysql transaction 1) Default transaction: ...

Overview of select statement There are three common functions of keyword select ion in query statements: single-table query, multi-table join query and sub-query. All the following introductions are about manipulating this table create table tml //Main table, two fields, ID (primary key self-increasing) and name (non-empty) ...

Label PostgreSQL, garbage collection, parameters, freeze background What parameters or factors will affect or control the garbage collection of PostgreSQL? parameter Global parameters 1. Control the sleep time of VACUUM command. When the stage COST of vacuum is larger than vacuum_cost_limit, sleep will continue after a period of time. va ...

Why can't 80% of yard farmers be architects? >    Usually, we use SQL to extract some columns from the database that meet the requi ...

PDO Extension PHP natively provides PDO extensions, meaning PHP data objects. Database Links and DSN DSN refers to the name of the data source, providing detailed information about database links. Generally, it contains the following information: Host name or IP address Port number Database name character set The DSN constructed by the above ...