db2 query performance tuning tips

number smaller than their own, the right to put bigger than their own dataFeatures: Fast Range search Speed3. Create an index:Normal index:CREATE INDEX name on ... Table of: ColumnCREATE INDEX Zhanggen on day61. ' User ' (email);Unique index:Create unique index index name on table name (column name)Drop unique index index name on table nameCombined index (leftmost prefix match):Create unique index index name on table name (column name, column name)Drop unique index index name on table nameCreat

the data processing to the SSAS Cube Dimension (also disk files), again generate unequal disk overhead, in addition to distinct to recalculate, the former need to the membership dimension of this large table to do tier to heavy, the latter only need to the membership level this small dictionary table to do the heavy, obviously the calculation is different weight class, These are just the cost of the process, perhaps you are doing in the night, not care these, then the

Performance Tuning is not a simple task. There is no omnipotent solution at all, but you can use some basic principles to implement it. In general, performance tuning is the role of DBA. however, DBA does not have time to carefully check every change made to the stored procedure. so learning some basic

Original addressMySQL is a powerful open source relational database management system (RDBMS). It was posted on 1995 (20 ago). It uses Structured Query Language (SQL), which may be the most popular choice in database content management. The latest MySQL version is 5.6.25, released on May 29, 2015.An interesting fact about MySQL is that its name comes from the daughter "My" of Michael Widenius (the founder of MySQL). Although there are many interesting

prevents people from overwriting the length () method. In addition, if you specify a class to be final, all methods of that class are final. the Java compiler will look for opportunities for inline (inline) all final methods ( This is related to the specific compiler implementation ). This will increase the performance on average 50%. 1.6 Use local variables as much as possibleparameters that are passed when the method is called and temporary varia

) name:@"IdleNotification" object:nil]; NSNotification *notification = [NSNotification notificationWithName:@"IdleNotification" object:nil]; [[NSNotificationQueue defaultQueue] enqueueNotification:notification 　　postingStyle:NSPostWhenIdle];} Five, memory optimization Use Autorelease pool to reduce memory spikes Six, Code details optimization 1, not in the viewwillapear time-consuming operation 2. If the key code is more efficient with C/C + + Seven, picture optim

some code that can be used to parse the ISO-8601 date string, and simply rewrite it to use it.Well, just use C to make it look good, but do you believe that we have a better plan!If you can control the date format you are working with, try to choose a Unix timestamp. You can easily convert from timestamp to NSDate:-(nsdate*) Datefromunixtimestamp: (nstimeinterval) timestamp {return [nsdate Datewithtimeintervalsince1970:timestamp]; }This will be faster than using C to parse the date string!It is

Tags: Practice login 16px between multiple connect shut down database SQL business logic　　The end of 2016 was the stage where I learned to understand the entire front end, backend, and database programming. During the practice programming process, notice that there is a scene between the server and the database: Start linking Database SQL--- $loginin =mysql_connect ("192.168.10.253:3306", "root", "123456"); To the end of the entire business logic, do not add a channel that closes the SQL linked

The simplest and most effective Bufferpool A buffer pool is a storage area in the memory. It is used to temporarily read and modify database pages (including table rows or index items ). The buffer pool is used to improve the performance of the database system. Accessing data from the memory is much faster than accessing data from the disk. Therefore, the fewer times the database manager needs to read or write data to the disk from the disk, the bette

Windows 2000 TCP Performance Tuning tips Carl HarrisCommunications Network servicesvirginia tech I was dismayed by the rather dismal TCP Performance in Win2000, especially for FTP up/downloads to distant sites, where the round-trip time (RTT) is nearly triple-digit. being a Unix bigot of sorts, I also found it amusing

, the not-in clause performs an internal sort and merge. In either case, not in is the least effective (because it performs a full table traversal of the table in the subquery). To avoid using not, we can change it to an outer join (Outer Joins) or not EXISTS. 20. Replacing exists with a table connection typically, table joins are more efficient than exists 21. Replace distinct with exists when you submit a query that contains one-to-many table inform

an execution plan, and stored in a database of SQL statements, is a collection of control flow language, the speed of course fast. 48, the return value of the function is not too large, this overhead is very large. A user-defined function that executes as a cursor consumes a large amount of resources if a large result is returned with a stored procedure. 49, as far as possible to avoid repeated access to the same or several tables, especially the large number of data tables, you can consider th

The DB2 tutorial you're looking at is: Tips for improving Insert performance in DB2 (1). Overview of the INSERT processing processFirst let's take a quick look at the process steps when inserting a row. Each of these steps has the potential to optimize, which we will discuss later. Prepare the statement on the c

Loops are a very common control structure, most things depend on it to do it, in JavaScript we can use for (;;), while (), for (in) three loops, in fact, in these three loops for (in) is very inefficient because he needs to query the hash key, As long as you can, you should try to use less. for (;;) The performance of the while loop should be the same as the basic (usually used) equivalent. In fact, the use