tuning oracle sql queries

Tag: Time Condition number column arch OSI user CTE codeIn section 1.5 of the SQL Tuning Basics Overview 05-oracle Index Type and introduction, several "Common index execution plans" are mentioned: Index full Scan: Fully scanned indexes, block read, orderedIndex range Scan: Range sweep of indexIndex fast full Scan: Fast all scans of indexes, multiple rea

To improve performance, we have tried a number of ways or scenarios that the Oracle database itself has provided, mainly including: Shared server mode (MTS)Cluster technology (clustering) RACPartitionParallel processing (mainly parallel queries) These features provided by Oracle are indeed used for performance improvement, but we often ignore the analysis of our

How to dynamically number rows and add row numbers in SQL is a classic problem in database queries. How to dynamically number rows and add row numbers in SQL is a classic problem in database queries. (1) display and sort row numbers 1. SQL Server row number A.

, make sure that the goal of performance tuning From the most intuitive, most common point of view, mainly includes the following two points: Optimizing Response Time What is "Optimizing response time"? The popular point is that after tuning, the execution of queries, updates, and other operations, the database reaction faster, the time spent less. More commo

As mentioned in parts 1th and 2nd, there are several relatively easy steps to improve performance you can take, one of these steps involves using an automated tool to "guide" you to write SQL statements, there are many production performance analysis or performance tuning tool manufacturers, in the following article, We will examine one of them. Quest Software Many DBAs and developers use a tool called To

Tracefiledatatablewhere eventclass=12--equals 12 for batchcompleted events and cpu2. What are the most resource-intensive queries?? Is the amount of CPU time, and the number of read/write Io. Recommended events include Connect, Disconnect, ExistingConnection, sql:batchcompleted, rpc:completed, and columns that contain WRITES,READS,CPU.3. Detect deadlocks?? In a database with a large number of accesses and concurrency, if the design is slightly unreas

, it mainly includes the following two points: Optimized Response Time What is "optimized Response Time? In other words, after optimization, when performing queries, updates, and other operations, the database responds faster and takes less time. It is quite common that it may take three seconds to execute an SQL query statement. After the index is added, it will take less than one second. Add indexes, whic

The Oracle database queries the year, month, day, and 24 hours (Instance) of the day in the time range according to the time range, and the oracle databaseYear in the query time range SELECT TO_CHAR ( ADD_MONTHS ( TO_DATE ('2013', 'yyyy'), (ROWNUM - 1) * 12 ), 'yyyy' ) AS yearsFROM DUAL CONNECT BY ROWNUM Query t

Oracle Adjusts Oracle's competition One of the benefits of Oracle is that it manages the free space in each table space. Oracle handles the space management of tables and indexes so that we don't have to understand the internal workings of Oracle's tables and indexes. However, for an experienced Oracle

as lide '%5400% ' queries that do not reference the index, and a "x5400%" reference to the scope index.7, where the condition order after the influenceThe condition order after the WHERE clause has a direct effect on the query of the large data scale. Such as:SELECT * from zl_yhjbqk where dy_dj= ' 1KV below ' and xh_bz=1;SELECT * from Zl_yhjbqk where dy_dj=1 and dy_dj= ' 1KV below ';The above two queries,

clearly not the best in terms of performance bottlenecks. Typically starts with a filter set to 100 milliseconds and then works from the beginning. The method is to increase the signal-to-noise ratio on each iteration, eliminate the smaller queries, and keep only those queries with higher potential for performance tuning. Depending on the application and server

oracle| Data | database | Performance Oracle is a high-performance database software. The user can adjust the parameters to achieve the optimization of performance. Performance optimization is mainly divided into two parts: first, the database administrator through the adjustment of system parameters to achieve the goal of optimization, the second is the development of the application of the optimization to

level, you should create an index on both the employee department and the employee post level fields. InvasiveThe performance gains from indexing to retrieval are often huge, so the first thing you should think about when discovering a slow retrieval speed is to create an index.②: Using Precompiled queriesIn a program where SQL is executed dynamically based on the user's input, you should use parameterized SQL