improve linq query performance

The most important component of Oracle SQL running time is the time spent preparing new SQL statements for execution. However, if you understand the Inherent Mechanism of executable plan generation, you can control the time spent by Oracle in evaluating the table connection sequence and improve query performance in general. 　　 Prepare the SQL statements for execu

This article is based on MySQL. Many content applies to other relational databases at the same time and requires some indexing knowledge. It focuses on how to optimize SQL to improve database performance. This article is based on MySQL. Many content applies to other relational databases at the same time and requires some indexing knowledge. It focuses on how to optimize SQL to

1. Storage Partition the hard disk into NTFS format. NTFS is faster than FAT32, And you can view the size of your data file. You can use multi-database files for 1 GB or more, in this way, the access load can be distributed to multiple physical hard disks or disk arrays. 2. tempdb Tempdb should also be placed on a separate physical hard disk or disk array. We recommend that you place it on RAID 0 so that it has the highest performance. Do not set the

indexing and using indexes does not respond much to the program, so programmers ignore the possible performance differences between different implementations when writing programs , this performance difference is particularly noticeable when the volume of data is particularly large or in large or complex database environments, such as online transaction processing OLTP or DSS for decision support systems.

differences between different implementations when writing programs , this performance difference is particularly noticeable when the volume of data is particularly large or in large or complex database environments, such as online transaction processing OLTP or DSS for decision support systems. In practice, poor SQL often comes from inappropriate index design, non-sufficient connection conditions, and a WHERE clause that is not optimized. After the

can use it to store user information and shopping commodity information, which can reduce the server burden caused by Session usage. But here One small problem is that when a user exits or submits an order to delete the items in the Cookie, we usually use setting the Cookie. Expires attribute to invalidate the Cookie, I don't know if this is the case. Using C # to invalidate a Cookie is sometimes different from using JavaScript to invalidate a Cookie, for example... The time for a computer is n

Preparedstatement How to greatly improve performance By BILLY Newport This article describes how to use prepared statements correctly. Why does it make your application program run faster and Database Operations faster. Why? Prepared statements Very important? How can I use it correctly? The database has a very hard job. They accept SQL queries from many concurrent clients and execute the queries as quickly

usage by avoiding double buffer. O_direct is a flag related to Linux IO scheduling and is called in the Open function. Files opened with the O_DIRECT flag will not be used to read or write to the file system cache. Traditional databases (ORACLE, MySQL) basically have o_direct-related switches that improve performance while reducing memory usage. As for Posix_memalign (), it is used to apply the aligned mem

Philosophically speaking, eliminating bottlenecks is the only way to improve server performance and concurrency capabilities.If you can eliminate all bottlenecks, you will be able to maximize the performance of the hardware, so that the performance and concurrency of the system to reach the best.Use multi-threaded mult

' OperationSimilarly, for the ' * ' operation, using the shift operation will be faster and more efficient as int num = a * 4;int num = a * 8; should be changed to int num = a Note:16, 17, the individual does not quite agree with these two articles. This does have better performance, but at the expense of readability. These two operators are not intuitive to many programmers. I think it's a good choice to sacrifice some

Tags: master memcached replication ParallelHow to improve the performance of replication:Delay:For MySQL replication, in the absence of a failure, the master and slave data are out of sync, and the delay is divided into the following two scenarios:Recurrent delay: The data gap between asynchronous synchronizations is larger, cyclical, and cyclic.Transient delay: unexpected condition, resulting in delayThe m

In SQL query in order to improve query efficiency, we often take some measures to SQL optimization of query statements, the following summarizes some of the methods, there is a need to reference. In the optimization experience of a carrier has encountered a more interesting SQL, as follows: 1 The initial SQL execution

. The CTE can refer to itself, or it can refer to a pre-defined CTE in the same with clause. Forward references are not allowed.5. The following clauses cannot be used in CTE_query_definition:(1) COMPUTE or COMPUTE by(2) ORDER by (unless the TOP clause is specified)(3) into(4) OPTION clause with query hint(5) for XML(6) for BROWSE6. If the CTE is used in a statement that is part of a batch, then the statement before it must end with a semicolon, as sh

How to improve the processing speed (to) of millions of databases to process millions of databases 1. to optimize the query, try to avoid full table scanning. First, create an index on the columns involved in where and orderby. 2. Try to avoid null value judgment on the field in the where clause; otherwise How to improve the processing speed (to) of millions of d

Java concurrent package 10, appropriate use of some high-efficiency algorithms. 11. Memory Consistency: Happen-before relationship of memory operations (such as read and write of shared variables). Only a write operation Happen-before read operations guarantees that the result of one thread's write is visible to the other thread's read. Synchronized and volatile tectonic happen-before relationships, Thread.Start () and Thread.Join () methods form happen-before relationships. 12, the JVM's

The time spent preparing new SQL statements is the most important part of the execution time of Oracle SQL statements. However, by understanding the internal execution plan generation mechanism of Oracle, you can control the number of times that Oracle spends evaluating the connection sequence and improve query performance in general. Prepare to execute SQL state

In the key points of Oracle performance adjustment, it is also very important to improve the efficiency of the block. We also need to pay attention to some things in improving the efficiency of the block. The following is a detailed description of the issues that need to be paid attention to when Oracle performance is adjusted to

We have to do not only write SQL, but also to write good performance of SQL statements.(1) Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a right-to-left order, and the FROM clause is written in the final table (the underlying table, driving tables) will be processed first, and in the case where the FROM clause contains more than one table, you must

; Spool OffSql> @d:analyze_tables.sqlSql> @d:analyze_indexes.sql 　　 Explanation: The above statement generates two SQL files, analyzing all the GAXZUSR tables and indexes, respectively. If you need to analyze the table by percentage, you can modify the script. Through the above steps, we have completed the analysis of the table and index, you can test the speed of improvement. It is recommended that the above statements be run on a regular basis, especially when data has been updated. Of cours

This article explains how to split an SQL statement with one or more left JOIN or right join into multiple SQL statements. MySQL query efficiency is very low, especially large data, and high concurrency, the index can not solve the problem, the best way is to split the SQL statement into multiple single table query SQL. Our company's electrical business website now to do Web services, Java to do middleware