DBA classic interview questions (1)

 2: How to view SQL Execution plans without using third-party toolsSet autotrace on If the following error occurs:SP2-0613: unable to verify PLAN_TABLE format or entitySP2-0611: An error occurred while enabling EXPLAIN reportRun oraclehome \ ora92 \

Enq: TX

  Session1:SQL> conn scott/trigerConnected.SQL> CREATE TABLE tx_eg (num number, txt varchar2 (10), sex varchar2 (10) INITRANS 1 MAXTRANS 1;INSERT into tx_eg VALUES (1, 'First ', 'female ');INSERT into tx_eg VALUES (2, 'second', 'male ');INSERT into

Use PL/SQL Developer to analyze PL/SQL code

  Click Tools ---> Preferences ---> Profiler. The configuration description is as follows (the current demo version is 9.0.0.1601)Available Columns -- Available Columns (can be moved to the right)Selected Columns -- Selected ColumnsTime units --

How should we design a database (3) (continued) (1)

After writing the previous blog "how to design a database (iii)", I deeply felt that I was not clearly written. It took a lot of space to describe the problem, however, the solution to the problem and its advantages and disadvantages were taken over

Upgrade from MySQL 5.1 to MariaDB 5.5.x

However, for those who have been using MySQL for a long time and are familiar with the MySQL ecosystem, changing MySQL is not so urgent. After all, it is not until the end of the day. However, it is time to come. Before Gentoo portage, the MySQL 5.5

Detailed description of Oracle cross-platform migration structure without data migration

This article describes Oracle cross-platform migration, such as migrating data from Oracle to other types of databases, but retaining the original structure. This reduces the workload of DBAs. I hope this article will help you better understand

An Analysis of the tablespace movement method in Oracle databases

Database movement is also a common phenomenon. After all, there are various reasons to force us to move. So how can we move faster? See the following. When using an Oracle database, data in the database is often moved from one database to another.

Use Performance Monitor to optimize SQL Server

There are many tools for Performance monitoring. First, we will introduce the Performance Monitor provided by Microsoft Windows Server. windows performance monitor is a very useful tool that can check the ways in which running programs affect

Case study of SQL Server connection failure in Windows 7

I. Problem In the home advanced edition of Win7, an inaccessible error occurs when accessing SQL Server. For details about the connection and error, see:   Ii. troubleshooting After learning, we found that the port number of SQL Server has been

Three considerations for database standardization

To reduce IT complexity and improve data quality, enterprises always want to integrate their businesses to fewer database platforms. However, experts believe that before the database standardization project, pay attention to cultural and technical

Overview of Oracle database architecture

Oracle Database system is a complex software system. The Oracle architecture refers to the relationship between the components of the Oracle database management system and these components, including the memory structure, background process,

SQL Server database minimal downtime migration Solution

I. Purpose When maintaining the SQL Server database, when the boss asks us to move dozens of GB of data files to other servers and requires the minimum downtime, do we have any solutions to meet these requirements? Here we assume that these two

Detailed description of the Access database management password method

Guidance:InAccess DatabaseIs embedded into a very strong database operating language-Visual Basic language, so you can use Visual Basic to write programs to implement some complex functions. The following describes how to implement encryption in the

Demonstrate the feasibility of DataReader Paging

I remember that it was one afternoon in. I was visiting the Internet and suddenly saw a piece of code, similar to the code above the landlord. The code was paged through DataReader. At that time, I was shocked. Is such code useless for a slightly

Teach you how to implement MySQL dual-host data synchronization (1)

Editor's note: many friends may not know where to start when getting started with MySQL's dual-machine synchronization requirements. In fact, this is one of the functions supported by MySQL itself. This article provides a preliminary idea about

How to capture the butterfly in the Butterfly Effect

A butterfly in the South American jungle flags wings and may cause heavy snow in Moscow, indicating the complexity of the atmospheric system. However, DBAs often face similar problems in their daily work. We analyze the symptoms of faults to solve

Cartesian product of SQL

What is Cartesian product? The implementation of cartesian products in SQL is not only Cross Join ). All join methods are converted into temporary Cartesian Product tables. Cartesian product is a concept in relational algebra, the number of rows in

How to use Excel to operate Oracle

Have you ever thought about a problem? Excel is the most commonly used tool to store data. However, when the number of data items is too large, it may be inconvenient to query. Can you connect Excel with a database to facilitate data use? This

What is Bloom Filter for massive data processing?

What is Bloom Filter] Bloom Filter is a space-efficient random data structure. It uses a bit array to easily represent a set and determines whether an element belongs to the set. The efficiency of the Bloom Filter has a certain price: when

MySQL 5.5.19 release attachment download

MySQL 5.5.19 is released. Improvements to this version include: New Feature ◆ By creating a cache for the metadata lock object, the performance of the metadata Lock operation in Windows XP is improved, which allows the server to avoid high-cost

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