tuning oracle sql queries

(PQO). The index will not be used for parallel queries.12th, see if it is useful to bind variables in PL/SQL statements. Because the database does not know what the bind variable is, when doing a non-equal connection, such as ' Two effective ways to track debugging:One is the Explain table method. The user must first establish the Plan_table table in his or her schema (schema), and each step of the executi

shortcomings. 8. SQL Server 2008 query performance tuning this book is a more practical book that describes the discovery of various bottlenecks, performance baseline resume, and performance analysis from the perspective of queries and stored procedures, this section describes possible performance issues. 9. pro SQL S

In 10 Gb, Oracle launched its own auxiliary SQL optimization tool: SQL optimizer (SQL Tuning Advisor: STA), which is a new DBMS_SQLTUNE package. To use the STA, make sure that the optimizer is in CBO mode. However, I think this tool is only suitable for those who do not full

dbms_workload_repository. Create_snapshot;We can also use the Dbms_workload_repository package to complete the baseline, modification of the default settings and so on.ADDM (Automatic Database Diagnostic Monitor AWR)is a consultant system within Oracle that can automate some of the optimization recommendations for the most databases, give recommendations for SQL optimization, index creation, and statistics

Chapter 2 procedural performance tuning of PL/SQL applications I. Reasons for PL/SQL Performance problems When the execution efficiency of PL/SQL-based applications is low, it is usually caused by poor SQL statements and programming methods, poor understanding of PL/

, and this is where Oracle is widely praised. SQL Server reads and writes are blocked from each other, in order to improve concurrency performance, for some queries, you can add nolock, so that the reading can be allowed to write, but the disadvantage is that it is possible to read the dirty data uncommitted. There are 3 principles for using NOLOCK. (1) The resul

ObjectiveIn the previous articles, we introduced a series of descriptions of operators and the optimization methods and techniques for each operator. This includes a series of our common operators, including how to view execution plans, how several datasets are commonly used, how to join operators, and parallel operators. Interested children's shoes can be clicked to view.In this article we introduce a series of sub-query statements, sub-query is generally the formation of some of the basic oper

of disk sorting will be greatly increased. This is mainly because at the end of the month, users will make statistics on the transaction data for the month. So at the beginning of the month, because of the number of transactions, so there will be more disk sorting occurs. In this case, it is necessary for the database administrator to adjust the relevant parameters. However, this adjustment is a temporary adjustment, until the cycle has passed, still need to transfer the parameters back. Only i

Label: Objective About SQL Server Tuning series is a huge content system, not a word two words can be analyzed clearly, this article first in the SQL tuning in the most commonly used query plan to parse, to do a good job of the basic grasp, tamping basic skills! Then we talk about the overall statement

is widely praised. SQL Server reads and writes are blocked from each other, in order to improve concurrency performance, for some queries, you can add nolock, so that the reading can be allowed to write, but the disadvantage is that it is possible to read the dirty data uncommitted. There are 3 principles for using NOLOCK.(1) The results of the query for "plug, delete, change" Can not add nolock!(2) The qu

It is troublesome to optimize an SQL statement before Oracle 10 Gb. However, the SQL Tuning Advisor tool launched in Oracle 10 Gb can greatly reduce the workload of SQL optimization, however, to use

. In this way, Oracle's read and write can be mutually exclusive, and this is where Oracle is widely praised. SQL Server reads and writes are blocked from each other, in order to improve concurrency performance, for some queries, you can add nolock, so that the reading can be allowed to write, but the disadvantage is that it is possible to read the dirty data unc

actually specified as the sqlid of the statement) --Generates an AWR report of an SQL statement, runs the script Awrsqrpt.sql Awrsqrpi.sql: Generates a statistical report of the specified SQL statement for the specified DB instance, specifying the snapshot interval; Awrddrpt.sql: Specify two different time periods, generate a statistical comparison report of the two periods; Awrddrpi.sql: Speci

An outline that is roughly written in the optimization content of the physical design and logical design of the DB, mainly physical design, logical design introduction of the content is not much, the outline of the physical structure design and example optimization of organic combination of the logical structure design and application adjustment together ... Oracle Performance Tuning Guidance outline Desi

access records in a table: A, full table scan A full table scan is a sequential access to each record in the table. Oracle optimizes full table scans in a way that reads multiple data blocks (database block) at a time. B, access to the table through rowID You can use ROWID access mode to improve the efficiency of the Access table, ROWID contains the physical location information recorded in the table. Oracle