by index

Page level: Engine BDB.Table level: Engine MyISAM, understood to lock the entire table, can be read at the same time, write notRow level: Engine INNODB, separate one-line record lock Table level, locking the entire table directly, and other

Explain is mainly used for select queries in SQL statements, can be displayed to view the SQL Statement index hit situation, so that better use of indexing, optimize query efficiency. The explain syntax is as follows: Explain [extended] select ...

using the reverse index (index DESC), you can significantly increase the performance of SQL statements with an ORDER BY DESC clause. first, the scene 1, table name: test_t, there is a field named object_id 2, total data quantity: 580000 line,

I java,net get started, of course Python also want to learn well, these days to introduce the Python object-oriented Object-oriented programming requires the use of classes, classes and instances, and with classes we have to create an instance to

/** * This article is simply a comb through the current standard of the array object of the band method. * The full text does not have any nutrition, but the final performance test part, has thrown out some questions. */ Assignment Method (Mutator

When I saw the SQL statement optimization yesterday in the book, where is the order of the conditions and the performance is different, is this suggestion appropriate in the oracle11g version? Mode 1 better than Mode 2? Mode 1: Copy Code code

Objective Sorting is a basic function of the database, and MySQL is no exception. The user is able to sort the specified result set by the order BY statement, not just the order by statement, the Group by statement, and the distinct statement

Installation Configuration Pycharm Official Download Address: http://www.jetbrains.com/pycharm/CSDN Download Address: http://download.csdn.net/download/coofly/6637569 Adjustment of color scheme:File–>settings–>editor–>colors & Fonts Selection

This is the third of the Python introductory tutorials, which will specifically describe the four types of data structures commonly used in Python, which are lists, tuples, collections, dictionaries, which are often used later, so you need to

Array Categories: 1, from the array of subscript divided into index array, associative array Copy Code code as follows: /* Index array, that is, an array that is usually called/ var ary1 = [1,3,5,8]; Array elements by index,

oracle| problem Index is a common database object, it is set up and used properly, which greatly affects the performance of database applications and databases. Although there is a lot of data on the use of indexing, DBAs and Developer often deal

The Redis key (Key) command command describes the Redis DEL command, which is used to delete key in key presence. The Redis Dump command serializes the given key and returns the serialized value. The Redis EXISTS command checks to see if a given key

Objects | data | database | statistics If Oracle uses cost analysis when executing SQL, all cost analysis sources rely on the system's statistical analysis table (Dba_tables, dba_indexes, dba_tab_columns) data, if the statistical analysis data is

[Uboot] uboot process series :[Project X] tiny210 (s5pv210) power-on START process (BL0-BL2)[Project X] tiny210 (s5pv210) load code from storage device to DDR[Uboot] (chapter I) uboot process--Overview[Uboot] (chapter II) uboot process--UBOOT-SPL

Redis supports V data types: string (string), hash (hash), list, set (set), and Zset (sortedset: Ordered collection). Redis defines a rich primitive command that can interact directly with a Redis server. In practice, we do not use these primitive

About RedisRedis is one of the industry's leading key-value NoSQL databases. Similar to memcached, it supports storing more value types, including string (string), list (linked list), set (set), Zset (sorted set-ordered collection), and hash (hash

For everyone to share a case of SQL optimization we encountered, the case is not my own responsible database, I am just a porter.This case occurred last year, discovered because the Nets host CPU rose, the development operation found the DA, then

IntroductionIn this article, there is a query operation for a 41G size database that contains millions records, and if you take advantage of the index, you can reduce the operation time from 37s to 0.2s.So what is an index? What is the rationale for

-----Normal Operation PlanSet Autotrace traceonlySet Linesize 1000Select/*+index (t idx_object_id) */* from t where object_id=19;Execution Plan----------------------------------------------------------Plan Hash value:2041828949-----------------------

MySQL Optimization Topic Development--Wang YaoyuFirst, SQL Optimized1. Analysis and positioning strategies1. Learn the frequency of SQL execution through show status2, location execution inefficient SQL statement: ① through slow log positioning; ②