rownumObviously, this writing will result in reading the table first, then sorting, and then taking the first 5 records, the plan is as follows:If we write like this, the semantics are the same, but it saves a lot of reading and sorting costs:Select/*+ Index (T1,IDX1_T1) */* from T1 where rownumThe execution plan for this SQL is as follows:As you can see, the SQL does not follow the hint instructions and s
Tags: implementation mechanism originally page organizes tables based on free article content index ClustFollowing the book on SQL tuning (SQL tuning or SQL optimization) in the essentials of high-performance
Tags: and fast speaking tuning market buffer way a completely"High-performance SQL Tuning essentials and Case Resolution" a book has been launched, many enthusiastic readers on the contents of the book and some of the specific questions raised questions, because of the numerous readers plus my daily work busy, here on
11 simple Java performance tuning techniques, java Tuning
Most developers naturally think that performance optimization is complex and requires a lot of experience and knowledge. Well, it cannot be said that this is completely wrong. Optimizing applications to achieve optima
:16TAB1 small, TAB2 billion level above, two weeks data in tens of millions of.Lan Hua Main 16:13:22Ok.Orchid Island Main 16:16:29So change the SQL:with T1 as (Select count (t.c1), t.c1,t.c2,t.c3,t.c4,t.c5From Tab1 twhere T.c2 not in (' Val1 ', ' val2 ', ' val3 ', ' val4 ', ' VAL5 ')and C1 is not NULLGroup by T.C1, T.C2,T.C3,T.C4,T.C5)Select T1.c1,t1.c2,t1.c3,t1.c4,t1.c5from T1Where NOT EXISTS (Select/*+ Use_hash (m,n) */M.C1, M.C2,M.C3,M.C4,M.C5from T1 m,tab2 Nwhere N.c2 > Sysdate-14and m.c1 =
storage, but the benefits are largely negligible. Conclusion This article first of all, this article mainly describes the T-SQL statement tuning from the execution plan of the following, and introduced a few common simple operators, the next one will focus on some of our most commonly used operators and tuning techniques
Oracle Database 10g Performance Tuning tips and techniques is recommended. For Oracle performance test, diagnosis, analysis, and optimization, see!
Chapter 2 Basic index principles (beginner developer and beginner dBA). For Oracle index optimization, refer!
Chapter 4 tuning
:37YesOrchid Island Main 15:34:51Oh.Orchid Island Main 15:35:12Other, not quite understand your data in the situation, not very good fine optimization.Orchid Island Main 15:35:44Should still be quick.Snow Leopard 15:36:34GoodSnow Leopard 15:36:36Let me seeOrchid Island Main 15:37:16For example: The index of the other two tablesSnow Leopard 15:37:31WellOrchid Island Main 15:37:43The full table scan, although the table is small, but to 0.5s, should also be a small proportion.Snow Leopard 15:37:55I
Index plays an important role in database performance. The advantages and disadvantages of index design directly affect the efficiency of DB execution. Therefore, when performing DB tuning, some of them will start to process the index. SQL server also provides a good tool for Database Engine Tuning Advisor a
15 useful MySQL/MariaDB performance tuning and Optimization Techniques
MySQL is a powerful open-source Relational Database Management System (RDBMS ). It was released in 1995 (20 years ago ). It uses Structured Query Language (SQL), which may be the most popular choice in database content management. The latest MySQL v
weeks data in tens of millions of.Lan Hua Main 16:13:22Ok.Orchid Island Main 16:16:29So change the SQL:with T1 as (Select count (t.c1), t.c1,t.c2,t.c3,t.c4,t.c5From Tab1 twhere T.c2 not in (' Val1 ', ' val2 ', ' val3 ', ' val4 ', ' VAL5 ')and C1 is not NULLGroup by T.C1, T.C2,T.C3,T.C4,T.C5)Select T1.c1,t1.c2,t1.c3,t1.c4,t1.c5from T1Where NOT EXISTS (Select/*+ Use_hash (m,n) */M.C1, M.C2,M.C3,M.C4,M.C5from T1 m,tab2 Nwhere N.c2 > Sysdate-14and m.c1 = N.c1and t1.c2 = M.C2);Orchid Island Main 16:
can avoid Key lookup is perfect, let's revise non-clustered index to include it in the index with the Include keyword His fields are:[SQL]
DROP INDEX idx_non_clust_salesorddetaildemo_modifieddate on salesorddetaildemo
CREATE nonclustered INDEX idx_non_clust_salesorddetaildemo_modifieddate on salesorddetaildemo (ModifiedDate)
--Clear the cache, only for the development environment!
xf master# cd major-mysqltuner-perl-993bc18/#./ mysqltuner.pl You will receive detailed reports and recommended tips for MySQL usage. The following is an example of the output from the default MariaDB installation: MySQL Performance Optimization 15. Optimize and Repair MySQL database Sometimes tables in the MYSQL/MARIADB database can easily crash, especially if the server shuts down unexpectedly, the file system suddenly crashes, or the database is
statements. Using adbc in the abap environment is similar to using JDBC in the Java environment.
The reports and transactions they write can use any available interface to access the database.
Use DB2 parameters in SAP Open SQL
SAP supports a batch of DB2 parameters that can be added to Open SQL statements to affect how natural SQL statements generated from Open
Author: (US) Tony Andrews Translator: Chen Yong Yang Health Series name: Chapter Hua programmer library Publishing House: Machinery Industry Publishing House ISBN: 9787111425021 shelving time: -6-4 published on: July 4,: 16 webpage: 86 versions: 1-1 category: more about computers> DB2 SQL Performance Tuning tips computer books DB2
The following articles mainly describe the ultimate SQL Performance tuning Technology of DB2, including the impact of pointers on the Performance of DB2 databases, DB2 performance tuning technology and a detailed description of mo
Chapter 2 procedural performance tuning of PL/SQL applications
I. Reasons for PL/SQL Performance problems
When the execution efficiency of PL/SQL-based applications is low, it is usually caused by poor
both are created in the SGA but SQL plan directives have not yet been persisted to the Sysaux table space, and statistical feedback is used during the re-optimization period, ignoring the existence of SQL plan directives.Ø both are created but the SQL plan directives are persisted to the Sysaux table space, and the SQL
Label:Original: SQL Server Performance Tuning Training IntroductionHello everybody, this is the first blog post I wrote in the blogging park, and the reason I want to open this blog is a record of my interest in MS SQL Technology learning. As a computer professional graduates, their own grasp of the technology always
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