oracle pl sql performance tuning tips techniques

Tags: process optimizer consolidation requires merging auto overwrite session accessThe full execution order of the SELECT statement:The full execution order of the SQL SELECT statement: 1. The FROM clause assembles data from different data sources; 2. The WHERE clause filters the record rows based on the specified criteria, 3, the GROUP BY clause divides the data into multiple groupings, 4, uses the aggregation function for the calculation, 5, uses t

I. Description Oracle provides a profiler toolkit that allows you to view the performance of each module during PL/SQL Execution. You can download this script from MOS: Implementing andusing the PL/SQL profiler [ID 243755.1] You

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 comput

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

valuable, while the Oracle lock mechanism is more advantageous, allowing Oracle applications to be more comfortable with DML operations, but this does not mean that you can do whatever you do, and in reality, even a lot of senior developers, are not very understanding of the characteristics and application of Oracle transactions, so often unnecessary use of manu

Oracle is a large database with a C/SClient/Server structure. It is mainly used in the 4GLSQL language and has the advantages of being powerful, simple, and easy to learn. The working process of the C/S structure is: when the client c end) inputs and sends an SQL statement, it will be sent to the server S end through the network ), the result is analyzed and executed, and then returned to the client through

, which can significantly improve performance. Experience shows that the biggest improvement in SQL Server performance is due to logical database design, index design, and query design. Conversely, the biggest performance problems are often caused by deficiencies in these same areas. In fact, the essence of

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 lar

requires a sort operation, while the others need to perform at least two sorting. Typically, SQL statements with union, minus, and intersect can be overridden in other ways. If your database is well-sort_area_size, using union, minus, intersect can also be considered, but they are very readable.(34) Optimize GROUP by: Increase the efficiency of the group BY statement by filtering out unwanted records before group by. The following two queries return

at any time to modify the value of an optimization parameter to observe the result comparison before and after the adjustment. Use the new Opt_param hint to get The same effect. Select/*+ opt_param (' Optimizer_mode ', ' first_rows_10 ') * * col1, col2 ... Select/*+ opt_param (' Optimizer_index_cost_adj ',) * * col1, col2. . Oracle has released a large number of SQL prompts, and hints are const

I will share 11 practical tips on Java performance tuning and java Tuning Most developers think that performance optimization is a complicated problem and requires a lot of experience and knowledge. Yes, it is not wrong. It is not easy to optimize the application to achieve

Over the past decade, Oracle has become one of the most professional databases in the world. For IT professionals, it is important to ensure that Oracle's powerful features are used to improve the productivity of their companies. One of the most effective ways to do this is through Oracle tuning. It has a large number of tuni