Discover the world with our lifehacks

What is storage Group in DB2?

What is storage Group in DB2?

DB2® storage groups are a set of volumes on disks that hold the data sets in which tables and indexes are stored. The description of a storage group names the group and identifies its volumes and the VSAM (Virtual Storage Access Method) catalog that records the data sets.

What is the use of group by in DB2?

The GROUP BY clause allows you to find the characteristics of groups of rows rather than individual rows. When you specify a GROUP BY clause, SQL divides the selected rows into groups such that the rows of each group have matching values in one or more columns or expressions.

What are storage groups?

A storage group is a named set of storage paths where data can be stored. Storage groups are configured to represent different classes of storage available to your database system. You can assign table spaces to the storage group that best suits the data.

What is true for group by order by clause in DB2?

DB2 Order by clause is used to sort the result table values by the sort Key order. Here, sort key can be the column name or column number. Results can be sorted either by Ascending (ASC) or by Descending (DESC) order.

How do I create a storage group?

Create storage array group

  1. From the Manage page, select Manage Groups > Create storage array group.
  2. In the Name field, type a name for the new group.
  3. Select the storage arrays that you want to add to the new group.
  4. Click Create.

What is mainframe storage group?

The valid values for Storage Group Type are: VIO. Virtual I/O (VIO) storage groups are used to allocate data sets to VIO, which simulates the activity of a DASD volume. VIO storage groups do not contain any actual DASD volumes. You can put temporary data sets in VIO storage groups.

When would you use grouping in SQL?

The GROUP BY Statement in SQL is used to arrange identical data into groups with the help of some functions. i.e if a particular column has same values in different rows then it will arrange these rows in a group. Important Points: GROUP BY clause is used with the SELECT statement.

Can you group by multiple columns in SQL?

We can group the resultset in SQL on multiple column values. When we define the grouping criteria on more than one column, all the records having the same value for the columns defined in the group by clause are collectively represented using a single record in the query output.

What are storage groups used for?

A storage group, used with storage classes, separates the logical requirements of accessing data from the physical requirements to store the data. You can use storage group attributes to specify how the system should manage the storage group.

What are aggregate functions in Db2?

Introduction to Db2 aggregate functions An aggregate function operates on a set of values and returns a single value. The most commonly used aggregate functions are AVG() , COUNT() , MAX() , MIN() , and SUM() .

How is isolation level defined in Db2?

In Db2 you can specify the following four isolation levels: cursor stability (CS), repeatable read (RR), read stability (RS), and….Standard SQL defines four isolation levels that can be set using the SET TRANSACTION ISOLATION LEVEL statement:

  1. Serializable.
  2. Repeatable read.
  3. Read committed.
  4. Read uncommitted.

What is Stogroup?

A DB2 storage group , also known as a STOGROUP , is an object used to identify a set of DASD volumes associated with an ICF catalog, or VCAT. Storage groups and user -defined VSAM are the two storage allocation options for DB2 data set definition. A STOGROUP can be assigned to a database, a table space, or an index.