advanced oracle sql tuning

types of SQL statements that need to be used to increase the free space in the data block: The DELETE statement, and the UPDATE statement that updates the existing data value to a smaller size. In the following two conditions, the space freed by the above two operations can be used by subsequent INSERT statements:If the INSERT statement is in the same transaction as the above two operations (transaction) and is located after the statement that freed

Article Summary: Oracle is a database platform, and some projects use Oracle's database replication technology, which also encounters some problems, so here I have a personal understanding of Oracle's replication technology, hoping to help the project team with Oracle databases. The SQL scripts that are used in the text are validated to run. --------------------

This series of "T-SQL" is mainly for T-SQL summary.T-SQL Basics"T-SQL Basics" 01. Single-Table query-several SQL query questions"T-SQL Basics" 02. Join Query"T-SQL Basics" 03. Subquerie

read times. The ways to refine each statement are:Check Optimizer statistics，Check the interpretation plan for the most efficient access pathMeasuringtry to replace SQL constructs, and test for possible new indexes, manifested views, and partitions. Test the performance of the entire application using the optimized SQL statement. Is overall performance improved? The method is reliable, but somewhat dilator

Tags: style blog ar color OS using SP strong onFirst, memory adjustmentOracle 11g, Oracle unified the SGA with the PGA, the sum of the Memory_target parameter settings, that is, Max (SGA+PGA) Alter system set sga_max_size=1500m Scope=spfile;If the error is set to Sga_max_size>=memory_target (not equal, the PGA requires at least approximately more than 10 m of memory), the startup Nomount cannot be performed, but modifying the SGA command requires at l

of the SQL statement, and combine its resource consumption and related statistics, trace files to analyze its execution plan is reasonable;2, through the correction measures (such as adjusting the SQL execution plan, etc.) to adjust the SQL to shorten its execution time, here is the guiding principle of tuning is the

, Microseconds_per_second ms_per_sec, pct_of_time pct from Opsg_delta_report where Microseconds_per_second > 0; Monitoring the usage of indexes: With In_plan_objects as(SELECT DISTINCT object_name from V$sql_plan WHERE object_owner = ' SCOTT ')SELECT table_name,Index_name,CaseWhen object_name was NULL then' NO 'ELSE' YES 'END as In_cached_planFrom User_indexesLeft OUTER JOIN in_plan_objectsOn (index_name = object_name);4. Identify the SQL st

Label:1. Pure hand-crafted Tools: Programmer's hands Features: Handwritten client and server-side validation code 2. Semi-manual semi-automatic Tools: Jquery.validate (client) + dataannotations dataannotationsextensions (server side) Features: Client handwritten partial validation code, server side only need to declare validation rules 3. Fully Automatic Tools: Jquery.validate jquery.validate.unobtrusive (client) + dataannotations dataannotationsextensions (server side) Features: Only server-

Understanding Deadlocks When two processes hold one or a set of locks, while the lock held by another process is incompatible with the lock acquired by another process view. A deadlock will occur. This concept is shown in 15. Figure 15: A simple schematic of a deadlock Below we simulate a deadlock, as shown in Figure 15, 16. Figure 16: Simulate a deadlock As you can see, when a deadlock occurs, SQL Server does not stand idly by to let the two pr

Tags: merging RDBMS LTE data file nbsp Select line div2016-11-22Subquery: Scalar subquery inline view (In-line views) semi-join/reverse-connect scalar subquery Select followed by subquery similar to a custom function to overwrite an inline view (In-line view) from followed by a subquery similar to Design view sub-query A condom query is a garbage design that can cause performance problems. A semi-connection is a subquery that has a in/exists in the back of where it is followed by a subquery with

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

SQL Server database self-optimizing release time under large data volume:2013-12-17 15:19:00 Source: Forum anonymous Keywords: database development1.1: Add secondary data filesStarting with SQL SERVER 2005, the database does not generate the NDF data file by default, generally there is a master data file (MDF) is enough, but some large databases, because of a lot of information, and query frequently, so in

Oracle Advanced queue introduction, oracle queueOriginal link: http://www.oracle-developer.net/display.php? Id = 411Oracle Advanced queue IntroductionAdvanced Queue (AQ) is available in multiple oracle versions. He is an oracle na

Oracle Advanced Training Course 6th Study Notes by jackyang (JackYang.sh@gmail.com) Date: This course contains multiple experiments, has not yet passed the computer verification. Tspitr (recovery of tablespaces Based on Time points) is introduced to reduce losses. Advanced than dbpitr. Design Philosophy: If a table in a production database is deleted by mistake.

SQL advanced (9) functions, SQL FunctionsSQL advanced (9) function syntax built-in SQL function syntax is: SELECT function (column) FROM tableIn SQL, there are several basic function types and types. The basic types of functions a

Oracle Advanced Training Course 5th learn the pages in the notes of the notebook and Oracle9i Database Management Basics II ed 1.1 vol.2.pdf correspondence guide: http://blog.csdn.net/magus_yang/archive/2006/10/10/1328283.aspx Author: jackyang (JackYang.sh@gmail.com) Date: this course contains multiple labs and has not yet passed the computer verification. Review the last lesson, which is not completely res

Oracle (4) --) Advanced subquery ~) This section will discuss the more complex application of instant queries, mainly to simplify SQL and improve performance from the aspect, of course .. There are many ways to improve performance .. Today I attended a lecture on Oracle performance