index key

(I ' m sitting here-Seattle Airport at 7am Sunday waiting to catch the same flight to Boston that I caught II weeks a Go. Instead of TechEd, this time I ' m going to a training course at MIT. I ' d enjoy the air travel a lot and a bigger gap in

 As you know, MySQL currently has the following types of indexes: Fulltext,hash,btree,rtree.So, what are the functional and performance differences of these indexes?FulltextThat is, full-text indexing, currently only supported by the MyISAM engine.

Concept articleIndexing concept (index concept)A data structure for the related b-tree in a table or view. The index key column consists of one or more columns. You can have an inclusion column (sql2005). Used to promote SQL Server to find related

Hash tableA hash table (Hashtable), also known as a hash, is a collection of index key (key) and value pairs that are organized according to the hash program code of the index key (Hashtable). The Hashtable object is made up of a hash bucket (bucket)

Index Database object index: A way to combine data, which can be quickly queried to specific records in a database object table by indexed objects, is the most common way to raise performance. An index will contain one or more

Search Engine Algorithm Research Topic III: Introduction to Clustered and nonclustered indexesIntroduction to Clustered IndexesIn a clustered index, the physical order of the rows in the table is the same as the logical (indexed) Order of the key

Under the following conditions, MySQL will do a full table scan: The 1> datasheet is too small to do a full table scan faster than doing a lookup on the index key. This is usually done when the total number of records in the table is less than 10

1 An application-defined error or an object-defined error. 2 an application-defined error or an object-defined error. 3 This error number is obsolete and is no longer in use. 5 procedure Call or parameter is invalid. 6 overflow. 7 Not enough memory.

mysql> help alter tablename:  ' alter table ' description:syntax:alter [online  | OFFLINE] [IGNORE] TABLE tbl_name    [alter_specification  [,  alter_specification]  ...]     [partition_options]alter_specification:    table_options 

Type of index:Normal: Indicates normal indexUnique: Represents a unique, not allowed duplicate index, if the field information is guaranteed not to be duplicated such as a social security number used as an index, can be set to a uniqueFull TEXTL:

MySQL performs a full table scan under the following conditions:1> the data table is too small, and a full table scan is much faster than the search for the index key. This is usually done when the total number of records in a table is less than 10

Simple sorting of MySQL InnoDB Engine B + tree indexes, mysqlinnodb   Standard Source: http://www.cnblogs.com/wy123/p/7211742.html (The Source retained is not the right of original works. My work is far from reaching this level, just to link to the

This article mainly introduces the difference between the Key quotation marks and the no quotation marks of the php array index. there is a serious difference between the quotation marks and the no quotation marks, you can refer to the following

1. Read the data of indexkey to the cache. If this part of data is not read to DBCache, dbfilescatterreadwrite wait events may occur. 2. Sort the data of indexkey. If sort_area_size or pga_aggregate_target is not large, disksort may be performed. 1.

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

This article mainly introduces the difference between the Key quotation marks and the no quotation marks of the php array index. there is a serious difference between the quotation marks and the no quotation marks, you can refer to the following

php Execution Principle PHP is a very simple application, the development of a very high efficiency of a language, its weak type of variable can save the programmer a lot of time and effort to define variables, type conversion and so on. It is a

Previous | returned directory | next As the name suggests, the update of the cache does not change with the set time, but changes according to the modification time of a file. ExampleCodeFor example ): File dependency Cache Code highlighting

One, uniqueidentifier is a data type that stores the value of the GUID.uniqueidentifier data type is a 16-byte GUID.A column or local variable of uniqueidentifier data type can be initialized to a value in the following ways: By using the

1, realize the idea Public class Implements Dictionaryinterface, Serializable {Defining Hasheddictionary.java as the implementation of the hash dictionary, the dictionary implements the following functions:① adds an element to the dictionary,