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Some disorderly thing

The INITRANS, chain line, and the efficiency of the data buffer to read my database using Oracle 9i. I have the following questions: 1, INITRANS parameter indicates the database block operation of the affairs of the concurrency level. This parameter

select count (*) and select count (1) the difference between the (reproduced)

select count (*) and select count (1) the difference between the (reproduced) Effect: both return the same result. Meaning: When the count value of the parameter is specific (such as count (1), count ('a')), count parameter has no real meanin

Two types of queries and ways to delete duplicate records and performance comparison

Here I give two query methods, and delete duplicate records, use the rowid one is supporting the completion of, and the other one is with the analysis of the power function to complete. The efficiency of both methods is efficient relative to other me

SQL combined with a single index of the column index

Background: The current popularity of fast WEB, many web sites because the large flow of data and the occurrence of habitual server crashes, a query can only be applied in certain network environments. Unoptimized case of large amount of data when th

Statistics maximum and minimum respectively, of the time they

Statistics maximum, minimum, and the time they were there select t. *, (Select timestamp from hisdata where pointname = t.pointname and realvalue = t.minvalue limit 1) as mintime, (Select timestamp from hisdata where pointname = t.pointname and realv

Oracle group and group function

First, the group: Grouping function can be set to operate on the line and give a result for each group. Use group by column1, column2, .. by columm1, column2 group, that is, column1, column2 is a combination of the same group Second, the commonly use

Sybase Replication Server common Commands (II)

12. admin stats View the replication server operating statistics Syntax : Syntax admin { stats | statistics } [, sysmon | "all" | module_name [, inbound | outbound ] [, display_name ] ] [, server[, database ] [instance_id ] [, display |, save[, obs_i

<Pro Oracle SQL> - Chapter 5 - 5.5 Questions about Data

Questions about Data about data problems (page 134) I hope at this point you agree that you do need to concern yourself with how data is stored and how it should be accessed. Where do you find this information? The database can give you most of the a

Oracle function of time (turn)

Oracle function of time (turn) The time format used in the oracle in yyyy-mm-dd hh24: mi: ss and some differences in Java for the yyyy-MM-dd HH: mm: ss This is often easily blurred. I believe many people have had the experience of some of the data st

oracle management performance statement

View user's session for the user select * from gv $ session t where t.USERNAME = 'user'; Session according to statistics the number of users to select count (1), username from gv $ session t group by username Not release the number of con

select sysdate from dual in Oracle9i and 10g of the difference

In the 9i environment. SQL> select * from v $ version; BANNER -------------------------------------------------- -------------- Oracle9i Enterprise Edition Release - 64bit Production PL / SQL Release - Production CORE

HBase run map / reduce to close down Speculative Execution

What is Speculative Execution The so-called speculative execution, that is, when all the task began to run after, Job Tracker statistics of the average progress of all tasks, if a task where the task node machine configuration is relatively low, or C

An iterative development of the research: the real work began

We passed over a series of analysis, workload assessment and priority assessments, developing an iterative project, through a system user identification and evaluation after the company, we can finally start the real development work. In fact, the it

Oracle10g system management 5

34 Oracle Database data dictionary is the most important part, it provides a database of relevant system information. Dynamic performance since the start of a routine attempt to record the relevant performance information. Data dictionary is a collec

System.currentTimeMillis () a matter of time

Do not know if you have not encountered the following situation: long stime = System.currentTimeMillis(); String[] strs = str.split(" "); long sendtime = System.currentTimeMillis(); System.out.println("String.split() spend time:" + (sendtime - stime)

SQL Server 2008 index tips

Microsoft MVP and best-selling book "Hitchhiker's Guide SQL Server" author Bill Vaughn gives a brief index to use SQL Server 2008 skills. The theme is based Kimberly Tripp and Paul Randall (the two is the SQL Server high availability an

sql daily, weekly, monthly and yearly statistics

Such as: Table: consume_record Field: consume (money type) date (datetime type) I ask how to write sql statements were four daily, weekly, monthly, quarterly consumption. Such as: January 1200 yuan February 3400 yuan March 2800 yuan - Daily select su

excel function formula and techniques used to collect 5

With data on how the unit sum In the data unit must be added to the final statistics but also the sum, and ask how AutoSum? (Example: A1: 2KG, A2: 6KG ....., in the last line KG automatically calculate the total number). = SUMPRODUCT (- LEFT (A1: A5,

SQLServer performance data for SQL statement

Reprinted from: STATISTICS we can see by setting the time of the system of executing SQL. Options are PROFILE, IO, TIME. Described as follows: SET STATISTICS PROFILE ON: display analysis, compile and execute the quer

shell statistics log lines

Statistics log lines: 1. Wc-l nginx_access.log.2011-09-26 2. Awk 'END {print NR}' nginx_access.log.2011-09-26 3. Awk '{max = max> NR? Max: NR} END {print max}' nginx_access.log.2011-09-26 View number of visits per hour for the requ

Linux cluster time synchronization settings

11 sets of plans to look at Linux cluster time synchronization, the operating system to Ubuntu 11.04 x86 64 Bits Selected one of the as the time server (ntp server), the node with other nodes for time synchronization. 1, (mo

SQL's case and when to use

Case has two formats. Simple search function and Case Case function. -- Simple Case function CASE sex WHEN '1' THEN ' Male ' WHEN '2' THEN ' Female ' ELSE ' Other ' END --Case The search function CASE WHEN sex = '1' THEN ' Male ' WHEN sex = '2' THEN

How to enable the AutoTrace function sqlplus

By the following method to grant permission to Autotrace Everyone Autotrace if you need to restrict access, you can put on the public authority to mandate a specific user. D: \ oracle \ ora92> sqlplus / nolog SQL * Plus: Release - Produc

Sqlserver all keywords


Regular expression test code statistics gadget

import; import; import; import; public class Code { static long normalLines = 0; / / code static long commentLines = 0; / / comment static long whiteLines = 0; static boolean

Oracle performance tuning study notes (b) - Statpack (extended application help documentation)

Oracle's installation directory $ ORACLE_HOME / rdbms / admin / spdoc.txt Single-instance report on Unix: SQL> connect perfstat / perfstat_password SQL> define begin_snap = 1 SQL> define end_snap = 2 SQL> define report_name = batch_ru

Oracle: DBA interview questions to collect and continuously update

1 You leave the occupation because of What? A: Two reasons, first to more change in environment, and the second is the company's commitment to some of their own unfulfilled. 2 heat generated when the backup archive (total size) than if the same b

Use of Sybase sp_monitor

sp_monitor Description Displays statistics about Adaptive Server. Syntax sp_monitor [connection, [cpu | diskio | elapsed time]] [Event, [spid]] [procedure, [dbname, [procname, [, Summary | detail]]]] [enable] [disable] [Statement, [cpu | diskio | ela

Oracle user session query methods of information

Oracle database user session information should be how to query it? The following information on the Oracle user session query methods described in detail, hoping to help you. AD: Oracle user session, I believe we have a better understanding, here to

MongoDB (4) java api

java api applications, not jdbc ah, mongodb very strange, very strange, Examples include code, commonly used to add, modify, delete, statistics, paging, conditions, documents nested query Test code import java.util.HashSet; import java.util.Set; impo

See table below shows the analysis table

- Analysis analyze table COMPETITORITEMPRICE_partition compute statistics; - View the table size of table space accounted for the final analysis time SELECT * FROM User_Tables; - Sub-table SELECT * FROM User_Part_Tables; - Sub-table schedule SELECT *

Oracle performance tuning study notes (b) - ---- Oracle SQL TRACE and TKPROF to use

Oracle SQL TRACE And using TKPROF After the start sql trace information collected includes 1. Resolution Executive . Returns the number of data 2.cpu And the time the command 3. Physical read and logical read the number of 4. The number of records pr

over () rank () usage

When the bubble jar accidentally discovered in this function, the function analysis to know oracle is so powerful, in which over () function is used and is particularly special, it will record about their findings. Personal understanding: over () fun

Oracle Certification: Oracle statistics the total number of eligible columns

Oracle Certification: Oracle statistics the total number of eligible columns. Recent reports in the project need a query that used statistics in line with the conditions of a column number of the other columns. For example a table has the following s

joint multi-table query oracle, statistics query, group functions, order by, having, subqueries, set operations,

Joint multi-table query by connecting to a multi-table queries, multi-table query data from multiple tables, but the table must have the appropriate connection between the conditions. In order to query from multiple tables, multiple tables must be id

Case statement in SQL usage

In SQL, Case has two formats. Case is a simple search function to function and Case. Below I discuss with you the SQL Case statement usage. - Simple Case function CASE sex WHEN '1' THEN ' Male ' WHEN '2' THEN ' Female ' ELSE ' Other ' END - Case Sear

HSQLDB password change

Because of the current swing in write a desktop application, taking into account the future there may be other users, and the system itself is involved in more statistics, charts, so the need to use a database but the database is not possible to use

[Reproduced] in the cardinality of query plan (Cardinality) is calculated

[Reproduced] in the cardinality of query plan (Cardinality) is calculated Original: When using the CBO optimizer mode when, oracle query plan is generated, it will calculate the cost of each acces

mysql datetime in date and the difference in statistics

Type: mysql Table structure: CREATE TABLE `abc` ( `id` int(11) NOT NULL AUTO_INCREMENT, `create_date` date DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM ; Data: mysql> select * from abc; +----+-------------+ | id | create_date | +----+---------

Oracle's DBMS_PROFILER: PL / SQL Performance Tuning

By Amar Kumar Padhi <! - Content_start -> An application can always be fine-tuned for better performance with the use of better alternatives or with the new features introduced with every release of Oracle. Simply inspecting the code can bring

oracle index aggregation factor

Simple look clustering_factor Simply CLUSTERING_FACTOR for INDEX Degree of order and chaos degree of comparison between Table b*tree index Is sorted For example, in INDEX The first point to a rowid record Where in the DATAFILE table BLOCK#1 Line 1 Co


Role: DBMS_STATS.GATHER_TABLE_STATS tables, columns, indexes of statistical information. DBMS_STATS.GATHER_TABLE_STATS syntax is as follows: DBMS_STATS.GATHER_TABLE_STATS (ownname VARCHAR2, tabname VARCHAR2, partname VARCHAR2, estimate_percent NUMBER, blo

Index Full Scan vs Index Fast Full Scan

index full scan and index fast full scan is the same thing? The answer is no. Although the two look almost literally, but to achieve a completely different mechanism. We take a look at where the difference between the two? First, look at IFS, FFS can

oracle case when the use of summary

Oracle dbms_job package usage summary ORACLE CASE WHEN and usage of SELECT CASE WHEN Case has two formats. Simple search function and Case Case function. -- Simple case function case sex when '1' then ' Male ' when '2' then ' Female ' else ' Other '

Alibaba Druid open source platform for new projects

Alibaba Druid open source platform for new projects Druid is what? Druid is a JDBC component, which includes three parts: DruidDriver Proxy Driver, to model-based plug-Filter-Chain system. DruidData

Operating statement records database

1, the table look-up table exam_manage first 10-20 records: select top 10 * from exam_manage where emp_num not in (select top 10 emp_num from exam_manage) 2, a string padded to 10 bits, the original string is 123456, to be treated as 0000123456 right

Use SELECT 1 FROM Tab to improve efficiency

1 Statistics of the total number of records in a table: SELECT COUNT (1) / SUM (1) FROM tab; Explained: select 1 from table; and select anycol (the purpose of collection of any row in the table) from table; and select * from table is not from the eff

oracle update statistics

dbms_stats.gather_schema_stats (ownname => 'USER', cascade => TRUE);

Oracle analytic functions summary

First, the statistics Second, the arrangement in row_number () the same data set in accordance with the order of ranking data dense_rank () the same data the same ranking rank () the same data the same ranking, the same data in different data of the

mysql count function statistics

Sometimes some of the database often statistical data For example, grouped according to a certain field, each value is the number select field, count (*) from table group by field Results: Field name count (*) Group 1 N a Group 2 N a ... ... ...
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