by index

A table access by index ROWID batched may appear in the start of an Oracle 12C execution plan, official explanation: Table access by index ROWID Batched:means that Databa SE retrieves a few rowids from the index, and then attempts to access rows in

1. Defining a SequenceThis article describes how to define a sequence in the Python language. The syntax for defining a sequence is similar to an array in Java, using a pair of brackets to enclose the values of elements in the sequence.The following

Oracle Development Series (iii) table access by index rowid you do not know the INDEX back TABLE, rowid back TABLE1 Introduction Recently, the system often prompts a problem where the SQL query time is too long. After reading it, it is an SQL

1 IntroductionRecently, the system often prompts a SQL query for too long, and looked at a daily count of the day by the time stamp of the amount of SQL.The total data volume for the table is 53483065.The statements are as follows:Select COUNT

Python Create Listone of the data types built into Python is the list: lists. A list is an ordered set of elements that can be added and removed at any time.For example, by listing the names of all the classmates in the class, you can use a list to

Optimize the MySQL statement with ORDER by index Several guidelines for indexing: 1, reasonable indexing can speed up the efficiency of data reading, the unreasonable indexing will slow down the response speed of the database. 2, the more indexes,

The GROUP BY statement uses the B+tree index scan to be divided into two cases: loose scan, compact scan.Loose Index Scan (loosely scanned) is just a small portion of the key value that needs to be taken out of the index scan to complete a scan of

1. rangeofstring: Intercept the length of the specified string;2. substringToIndex:7：截取从0 索引到指定索引（7）长度的字符串 （从0到7）3. substringFromIndex:9：截取从指定索引（9）到末尾长度的字符串  （从9到0）4. substringWithRange:NSMakeRange（4，2）：截取从指定索引（4）到指定（2）长度的字符串

Tag: Ack Index des access specifies Lin pre first soPython accesses list by indexSince list is an ordered set, we can use a list to indicate from high to low the 3 students in the class:>>> L = [' Adam ', ' Lisa ', ' Bart ']So how do we get the

This article mainly introduces Python through the Index traversal list method, example analysis of Python traversal list of related skills, very practical value, the need for friends can refer to the The example in this article describes how Python

Although order by does not match the ORDER of the index, the index can still be used, as long as the unused index part and all the additional order by fields are included in the WHERE clause.Use the index MySQL OrderThe following queries use indexes

This article mainly introduces how to analyze the CPU load soaring caused by MySQL indexes, and introduces the huge CPU burden caused by independent indexes, to remind you to pay attention to the CPU load when using indexes in MySQL, you can refer

Although order by does not match the ORDER of the index, the index can still be used, as long as the unused index part and all the additional order by fields are included in the WHERE clause. Use the index MySQL OrderThe following queries use

Received a MySQL server load alarm, up a look, load average are more than 280, with top look, the CPU ran to 336%, but IO and memory load is not high, according to experience, should be an index caused by the tragedy. Look at the processlist and

Through the Partition Table analysis, we found that the original table structure was renamed without indexing, and a new table was created. After the analysis, we found that the index was used! Is it a partition storage parameter? Or the number of

Although an order by is not exactly the same as an index, an index can be used, as long as the unused index portion and all the extra orders by fields are included in the WHERE clause. Use the indexed MySQL order bySeveral of the following queries

In some cases, MySQL can use the index directly to satisfy an order BY or GROUP by clause without having to do extra sorting. Although an order by is not exactly the same as an index, an index can be used, as long as the unused index portion and all

Today, Galle asked me to optimize an SQL statement. The SQL statement is as follows: SELECT DISTINCT b.organ_id, c.company_name as organ_name, a.distri_date, a.distri_type,

Today, I encountered a strange problem at oracle10g. One SQL statement was very fast on database 1 and very slow on Database 2. Database 2's data was imported from database 1 and the data volume was similar. Run 0.01 s on database 1. SQL> SELECT .*,2

DBA Note: a dba diagnostic tool-Event 10046 and 10053 friend from an optimization tool manufacturer sent a case request to assist in diagnosis, it is unacceptable that a friend's optimization tool can produce results in 10 minutes when executing an