how to tune sql query in oracle

partitioned tables:1, the size of the table more than 2GB.2, the table contains historical data, new data is added to the new partition.(3). Advantages and disadvantages of table partitioningTable partitioning has the following advantages:1, improve query performance: The query on the partition object can only search their own care, improve the speed of retrieval.2. Enhance usability: If a partition of a 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

and select 'store'-data file. The following interface is displayed, showing the data file name and tablespace name, data File Size in MB, used data file size, and data file utilization rate. Figure 2 data file size and usage 2. Command Method for viewing data file information in Oracle Database: Query the data dictionary tables in the database system to obtain information about the data file. Firs

Oracle learning notes 3 SQL commands, oracle learning notes SQLSQL introduction SQL supports the following types of commands: 1. data Definition Language (DDL) 2. data manipulation language (DML) 3. transaction Control Language (TCL) 4. the Data Control Language (DCL) is a detailed note of the four

a single-row subquery to be included in the select clause. This is the oracle scalar query. scalar queries are similar to external queries, when using external connections, we can flexibly convert them into scalar queries. SQL> create table t1 as select * from all_users; Table created. SQL> create table t2 as select *

Oracle with other methods (such as: RowNumber). In a later discussion about the "paging display stored procedure for TENS data", we will use the keyword top.Iv. how the query optimizer operatesThe preferred process to go through when we throw a T-SQL statement to SQL Server ready for execution is the compilation proce

/* Use ms SQL to implement the T-SQL code for Distributed Query of heterogeneous databases */ Exec sp_addrole server 'Ms _ SQL ', '', 'sqloledb', '2017. 18.9.20'Exec sp_add1_srvlogin 'Ms _ SQL ', 'false', null, 'sa', 'capec '/* Create a sqlserver remote connection to the sq

solution 3: (using SQL cursor Stored Procedure paging) The efficiency is the worst, but the most common Iii. oracle paging Query Method 1: SELECT * FROM ( SELECT A.*, ROWNUM RN FROM (SELECT * FROM tab) A WHERE ROWNUM This page is less efficient than the following execution time. Oracle will be automatically opti

The word booksearch may be unfamiliar to many developers. Many people have encountered this word, but they have not paid enough attention to it, so they have always ignored its existence. The word booksearch may be unfamiliar to many developers. Many people have encountered this word, but they have not paid enough attention to it, so they have always ignored its existence. The growth of SQL Server Cognition 1. I don't have to graduate or work for

(SELECT * FROM TABLE_NAME) A) where rn between 21 AND 40 In most cases, the efficiency of the first query is much higher than that of the second query. This is because in the CBO optimization mode, Oracle can push the outer query conditions to the inner query to imp

information. Terminal products occupy 1000 pieces of information. In the query condition, if the product category is limited to "terminal", the query results may not be all terminals. Only the first 100 terminal products are displayed by default. To view all product information, you must click "show all" to display all information.In fact, no matter how many applications are designed, there are also restri

1: When performing multi-table join, use the Where statement to minimize the result set of a single table. Use the aggregate function to summarize the result set and associate it with other tables to minimize the data volume of the result set.2: When two tables are joined, you should consider whether to use right join. To increase the query speed3: Use where instead of havingWhere is used to filter rows, while having is used to filter groups, because

1: When performing multi-table join, use the Where statement to minimize the result set of a single table. Use the aggregate function to summarize the result set and associate it with other tables to minimize the data volume of the result set.2: When two tables are joined, you should consider whether to use right join. To increase the query speed3: Use where instead of havingWhere is used to filter rows, while having is used to filter groups, because

We have to do not only write SQL, but also to write good performance of SQL statements.(1) Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a right-to-left order, and the FROM clause is written in the final table (the underlying table, driving tables) will be proc

The growth of SQL Server Cognition 1. I don't have to graduate or work for a long time. I only know the relationship between SQL and SQL Server Oracle and MySql. I usually think that SQL is SQL Server. 2. after several years of w

Small Program Ape SQL Server Cognitive growth 1. Did not graduate or work not long, only know that there is a database, SQL such dongdong, unaware of the SQL and SQL Server Oracle, MySQL relationship, usually considered SQL is

voodoo magic. SELECT B.sid, b.serial#, A.spid ProcessID, b.process clientpid from V$process A, v$session bwhere A.add R = b.paddr and B.audsid = USERENV (' SessionID '); V$session. SID and V$session. serial# is the database process ID V$process. SPID is the database server background process ID V$session. Process is the client process ID, On Windows it is:separated the first # was the PROCESS ID on the client and 2nd the the THREAD ID. 32. Query

part. Therefore, if the character set between the two databases is the same as that in the third part, data can be imported and exported to each other. The preceding information is only prompted in Chinese or English. 2. view database character sets This involves three character sets, The first is the character set of the kernel El server; The second is the character set of the Oracle client; The third is the DMP file character set. During data impor

$ sqlarea QWhere S. paddr = P. ADDRAndS. Sid = PAndS. SQL _address = Q. address;Query Based on the SID determined by the previous SQL statement. Result: Oracle and CPU resources The Oracle Database shares CPU resources with all other software running on the same serve

second, need to stitch SQL statementsPaging Scenario Three: (using SQL Cursor stored procedure paging) is the least efficient, but most versatile Third, Oracle paged query Method One: SELECT * from (select A.*, rownum rn to (SELECT * from tab) A where rownum This paging has less execution time