using index condition using filesort

frequently use. Whenever possible, you should try to create a unique clustered index for a table to enhance query operations. Finally, you need to create an index for multiple fields -- composite index -- the index creation statement contains multiple field names at the same time. The following example creates an

1. Use the Explain statement to view performance mysql> explain select product_id from Orders where order_id in (123, 312, 223,, 224) \g2. Why create a composite index? If there is only one index, the 2 query criteria will first go to the index to query a condition, and then MySQL will go to the table on the disk to qu

, and ,, jin,, Dal and 檎? Fan undercover  Zhuo Shui throw  Riddle Wu ┧ the gourmands  the noisy bed 檠? Kill the noise from the PostScript 旆  Jin 鞯 queue frequency  牟檠 estimate vinegar Far oh well  Щ 牟檠  enzyme 鞯  n yi Ji ji 谩 ju cloth   Undercover Chant school  Langfeng Magic emanation perch undercover  shuo  same shade occluded dui  , this is the issue discussed in this chapter, the goal is to optimize the performance of the database system, Make it work on a variety of que

How to create the best index? 1. Create an index explicitly Create index index_name on table_name (field_name) Tablespace tablespace_name Pctfree 5 Initrans 2 Maxtrans 255 Storage ( Minextents 1 Maxextents 16382 Pctincrease 0 ); 2. Create a function-based index It is commonly used in functions such as UPPER, LOWER, an

.000001 Shanghai Composite Index,sz.399106 , etc.. # #规模指数, for example:sh.000016 Shanghai 50,sh.000300 Shenzhen 300,sh.000905 certificate 500,sz.399001 exponentially, etc. # #一级行业指数, for example:sh.000037 Shanghai Pharmaceutical,sz.399433 National Certificate delivery etc; # #二级行业指数, for example: sh.000952300 real estate, sz.399951300 bank etc; # #策略指数, for example: sh.00005050 rights, sh.000982 500 etc; # #成长指数, such as:sz.399376 small plate gro

SQL Server data rows: Heap and B-tree (binary two fork tree). People who have learned the data structure know that the advantages of binary tree are: The rapid use of binary method to find data, data pages using a two-way linked list end-to-end connection. Let's introduce the heap in the data structure. The data in the heap is not in any order and the data page is not connected to the end. So how do you find the data in the heap? The structure and IA

Use index quick full scan (indexffs) to avoid full table scan reference: IndexFastFullScanUsageToAvoidFullTableScans (DocID70135.1) applicable to: OracleDatabase Use index quick Full Scan (Index ffs) To Avoid Full Table Scan reference: index Fast Full Scan Usage To Avoid Full Table Scans (Doc ID 70135.1) applicable: or

You can create an index on an existing table by creating an index at the same time. Method 1: Create an index when creating a table. When using this method to create an index, you can create multiple indexes (such as unique index,

directory of the website, an error will inevitably occur. How can we solve this problem? the corresponding solutions are also provided in the CodeIgniter manual: Change the last sentence: The code is as follows: RewriteRule ^ (. *) $ index. php/$1 [L] You only need to remove the slash before index. php.How to add a url suffix Through the above steps, we have hidden the

Label: /*SELECT Count (*) from (*/EXPLAINSELECTSt.id,st. Stu_name,tmpgt.time,tmpgt.goutong fromJingjie_students St Right JOIN ( SELECT * from_goutong Gttime, (SELECTname_id NameID,Max(time) time fromT_goutongGROUP byNAME_ID) GTWHEREgttime.name_id=Gt.nameid andGttime.time=Gt.time andGttime.time>'2015-07-19 16:18:02') TMPGT onSt.id=tmpgt.name_id; /*) student_latested;*/When a federated index is not used, the 'GROUP by name_id' query uses a full table

Label:differences and linkages between Oracle unique indexes and ordinary indexes Difference: Unique index and general index the biggest difference is that you add a single layer of constraint to the index column. A data column that adds a unique index can be empty, but it must be unique as long as the data value is re

catalog and then turn to the page numbers you need.3. Brief summary Indexes can improve query efficiency Clustered index A table can have only one, and a table with a nonclustered index may have multiple Clustered index storage records are physically contiguous, while nonclustered indexes are logically contiguous, and physical storage is not con

Using full-text indexing in MySQL (fulltext index)A useful feature of MySQL is the ability to find text using full-text indexing (fulltext index). Currently only valid when using the MyISAM type table (MyISAM is the default table type, and if you don't know what type of tabl

In fact, it is very easy to create indexes for the database in paie.net. You only need to read the records in the data table and then index each field. In this article, the database content is a blog table-userblog table. 1. Table Structure:Field Name field type field meaningId varchar (11) No.Title varchar (50) TitleContent text content 2. Procedure1) Open the database;2) create an index;3) perform full-t

% '; SELECT * from Tbl_name WHERE key_col like Other_col; In the first statement, the like value starts with a wildcard-wildcard. In the second statement, the like value is not a constant. If you use ... Like '% string% ' and string more than 3 characters, MySQL uses the Turbo boyer-moore algorithm Initializes the pattern of the string and then uses the pattern to search faster. If col_name is indexed, searches using