sql query running slow oracle database

execution plans. However, in practice we have also found a lot of such scenarios: sub-query speed, the amount of data is not small, but the slow after the connection, the result is to find the execution plan subquery is opened.By default, Oracle has a "small compute" feature when estimating the number of result sets for a multi-conditional statement. That is, th

Background: Oracle queries the current asset status, including asset information (table 1), Asset maintenance status (table 2), Asset retirement status (table 3)As follows:Asset Information:Asset Repair:Asset retirement:After the asset application is finished, you can apply for maintenance and scrap of the current asset, with two processes in service, one for maintenance and then maintenance. The corresponding need to start the corresponding process t

Syntax and introduction of SELECT statement in Oracle databaseSELECT [All | DISTINCT] From [WHERE [GROUP BY [ORDER by Statement Description:[] square brackets are optional[GROUP BY Refers to grouping results by the values of The phrase will be output only if the group satisfies the specified criteria.[ORDER by Display results sorted by The order in which the SQL clauses are executed:1. From2. WHERE3. GROUP

This weekend, when the Lord Bo was in his own Windows host, the Oracle database in the virtual machine was connected with Pl/sql, and there was a problem of approximately more than 10 seconds to log in to succeed. It's a strange phenomenon because I ping the Oracle server IP address in the virtual machine in Windows, a

Oracle optimizer and SQL query execution sequence before Oracle executes an SQL statement, it first needs to check the SQL Execution Plan and then execute the SQL statement according to

), variable length, can hold photos, files, etc. int, integer field. Example: Userage int float, floating-point data is approximate. Example: Userresults float, the approximate numeric data type used to represent floating-point numeric data. datetime, Date type. Example: Createdatetime datetime Bit, Boolean type. Can be set to True is male, false is schoolgirl If the content is very much, indeterminate length (such as article), can be used: nvarchar (max) 6. Save the tabl

After a DML statement is executed, the results of the DML statement are stored in four cursor attributes, which are used to control the program flow or understand the program status. When running DML statements, PL After a DML statement is executed, the results of the DML statement are stored in four cursor attributes, which are used to control the program flow or understand the program status. When running

Before executing an SQL statement, Oracle needs to first check the SQL Execution Plan and then execute the SQL statement according to the execution plan. The optimizer is responsible for analyzing the execution plan, under different conditions, an SQL statement may have mult

Tags: style blog http io color OS SP for strongTo synchronize data from Oracle in real time to MS SQL Server, you need to read and write data directly to SQL Server in Oracle, and you can install the Oracle database for

By separatingSQL statement for local range data scanning Generally, it is more effective to put all components of an SQL statement that implements a function together. However, in a few cases, the SQL separation method is more effective. This situation mainly exists in that when you query two tables with a 1: M relationship, the data used to filter the condition

Label:Getting started with the database running the original SQL lookup Once you've set up your database connection, you can use the DB facade to be searched. DB Facade provides a lookup method for each type:select,update,insert , Delete , Statement . the following brothers to help you introduce each. Run a Select Fi

uniquely identifies the current database user. USERReturns the username of the current user. USERENV ()Returns information about the current session based on opt. The optional value of opt is: SYSDBA role response in ISDBA session, returns TRUESESSIONID return Audit Session identifier ENTRYID return available audit item identifierAfter the INSTANCE is connected to the session, the INSTANCE identifier is returned. This value is only used when the Para

$ SQL = "select count (qid) from test_querys where istested = 1And qid Qid from $ left_cr where issubmit = 1 and qid $ SQL = "selectCount (A. qid) from test_querysA left join (select qid from $ left_cr where issubmit = 1 and rankval = 1 and qid 1. The first query takes 2.9 s, and the second query takes 0.2 s! Use in

not return any parameters. For this type of operation, you can use the statement method in DB facade:Db::statement (' drop table users ');Listen for Find events #If you want to be able to monitor every piece of program execution SQL statement, you can use the Listen method. This method is useful for record lookups and debugging. You can register your lookup listeners in the service container:namespace App\providers;Use DB;Use Illuminate\support\serv

This article introduces the database SQL recursive query in different database implementation methods, the specific contents please see below. For example, the table structure data is as follows: Table:tree ID Name ParentID 11 Level 0 22 Level 1 33 Level 2 44 Level 3 SQL