cascade dk

In the previous article, I wrote how to use gp_segment_id to determine whether the Dk value of the table has data. The following describes how to check the allocated unbalanced table by checking the amount of space occupied and re-adjust the Dk value. One of my greenplum machines, one of which has more data volumes than other nodes, shows the imbalance of data distribution, as shown in the following example

To test whether multi-Table association can be filtered by Image segment when multiple DK distribution keys exist, the test is as follows: [gpadmin @ gtlions50 ~] $ Psqlgtlionspsql (8.2.15) Typehelpforhelp. gtlions # createtablegtt1 (idint, namecharactervarying (5) distributedby (id, name); CREATETAB To test whether multi-Table association can be filtered by Image segment when multiple DK distribution keys

Thanks for kinglong's invitation not long ago. Now my Gmail has invited me. Today, I opened a Gmail surprise and found "invite a friend" in the lower left, 50 invitations. If you have any need, please reply to the DK invitation here: Http://www.sumso.com/dkblog/index.php? Action = show bid = 45 # feedback Note: Reply format: (your name) your current email (e.g. :( DK) w3cdk@yahoo.com) Note: I am only

Log Analysis of ETL background system data is currently underway. You can view the tasks that have been running for a long time, find the jobs that have consumed a long time, and optimize the logic and database layers. this article focuses only on Database optimization (including SQL statement adjustment and greenplum table DK adjustment ). view a job that takes about 30 minutes, find the corresponding source table, and perform the following analysis:

Tags: Image student round key cannot code also innodb intoFirst, create two tables STU,SC Create TableStu (SidintUNSIGNEDPrimary Keyauto_increment, namevarchar( -) not NULL) TYPE=InnoDB CharSet=UTF8; Create TableSC (SCIDintUNSIGNEDPrimary Keyauto_increment, SidintUNSIGNED not NULL, scorevarchar( -)default '0', Index(SID),--foreign keys must be indexed FOREIGN KEY(SID)REFERENCESStu (SID) on DELETE CASCADE on UPDATE

Mysql implements cascade operations (cascade update and cascade deletion) and mysql implements 1. Create two tables stu, SC Create table stu (sid int UNSIGNED primary key auto_increment, name varchar (20) not null) TYPE = InnoDB charset = utf8; create table SC (scid int UNSIGNED primary key auto_increment, sid int UNSIGNED not null, score varchar (20) default '0'

Hibernate Association, focusing on understanding cascade and Inverse 1. cascade is generally used for Cascade storage, cascade update, and cascade deletion. 1.1cascade annotation has two types, one is based on Hibernate Annotation Org. hibernate. Annotations.

Oracle foreign key cascade deletion and cascade updateCascading Deletion Oracle has three behaviors: no action (similar to RESTRICT), CASCADE, and set null. The following uses the student-class as an example to describe how to delete Foreign keys in different situations. A student belongs to a class and the primary key of the class is the foreign key of the stude

Oracle foreign key cascade deletion and cascade update, oracle key level update Cascading Deletion Oracle has three behaviors: no action (similar to RESTRICT), CASCADE, and set null. The following uses the student-class as an example to describe how to delete Foreign keys in different situations. A student belongs to a class and the primary key of the class is t

[Mysql] the disadvantage of external key cascade and cascade, mysql key-level disadvantage When creating a table, you can set delete and update to cascade. An example is used to describe the concept of cascade of Foreign keys. Assume that a usertable exists in the database as follows: This user table is very simple an

Oracle FOREIGN KEY (Foreign key) cascade Delete (delete CASCADE)TargetExamples of how to use cascading deletions in Oracle foreign keysWhat is cascading delete (DELETECASCADE)? Cascade Delete is when a record in the primary table (parent table) is deleted, and the associated record in the child table is automatically deleted.cascading deletions for foreign keys c

I have already used the association in my previous notes, but it is mainly a demonstration. In this article, I will analyze it in detail!Operation object using association relationship:The associations between data objects are one-to-one, one-to-many, and many-to-many. In database operations, it is difficult to process the association between data objects using JDBC. For example, when deleting information about a class, you also need to delete the basic information of all students in the class.

Label:SQL Cascade UPDATE, cascade Delete did a test today, made clear cascade Update, cascade DeleteCascade Delete: When we do not have a key to cascade Delete, delete the primary key table data (foreign key table has reference data), will be error, cannot delete, must first

The previous article introduced the cascade operation of Hibernate persistence object, this article introduces the cascade operation when reading.Or use the previous example, a questionnaire has a number of questions, but each problem can only belong to a questionnaire. Let's look at the test case first:@Test public void Testreadfromquestionnaire () {Session session = Sessionfactory. Getcurrentsession();Ses

idx_cpumodel (cpumodel ); Define Foreign keys The following describes how to create a constraint between two tables ". Because the CPU model of the pc must refer to the corresponding model in the parts table, we set the cpumodel field of the pc table to "foreign key" (foreign key ), that is, the reference value of this key comes from other tables. Alter table pc add constraint fk_cpu_model Foreign key (cpumodel) REFERENCES parts (model ); Cascade ope

key?Most people here say the foreign key, degree refers to the field name in a table that is constrained by a foreign key. This is a lot of people from the beginning of the default, in fact, not yet,Explanation: for each table with a FOREIGN KEY constraint constraint, the foreign KEY constraint relationship is given a name, which can be learned from the statement that sets the FOREIGN key constraint on the Table.CONSTRAINT foreign Key name FOREIGN key by foreign key constraint decorated field n

Css inheritance and cascade, css inheritance and cascade This section describes how to use the document structure and css selector to apply various styles to elements. Let's take a look at css cascade and inheritance. Let's talk about the concept first. Inheritance: the mechanism used by an element to pass attribute values to its child element. The popular point

Summarize:Cascade: To limit cascading operations, there are several parameters:All: associated operations are performed in all cases. None: Associated operations are not performed in all cases. This is the default value. Save-update: the associated operation is performed when Save/update/saveorupdate is executed. Delete: The associated operation is performed when the delete is executed. Inverse: In a one-to-many model, it can only be set on a single side, andinverse 's role is to update the pri

key?Most people here say the foreign key, degree refers to the field name in a table that is constrained by a foreign key. This is a lot of people from the beginning of the default, in fact, not yet,Explanation: For each table with a FOREIGN KEY constraint constraint, the foreign KEY constraint relationship is given a name, which can be learned from the statement that sets the FOREIGN KEY constraint on the table.CONSTRAINT foreign Key name FOREIGN key by foreign key constraint decorated field n

Three major Css mechanisms (features): particularity, inheritance, details of cascade, css Cascade Inheritance(Inheritance) is a mechanism used to pass attribute values from an element to its child element. When determining which values should be applied to an element, the user agent (browser) should not only consider inheritance, but also consider declaringSpecial(Specificity). In addition, you need to con