What can be the size of a page in Db2?
Pages can be four sizes: 4, 8, 16, and 32 KB.
How do I find the size of a Db2 database?
The database size is calculated as follows: dbsize = sum (used_pages * page_size) for each table space (SMS & DMS). An output parameter of type BIGINT that returns the database capacity (in bytes).
What is index page size in Db2?
Compressed indexes can use 8 KB, 16 KB, or 32 KB buffer pools. When you use compressed indexes, more index leaf pages can be stored on a disk. The index leaf pages are compressed down from either 8 KB, 16 KB, or 32 KB to fit into a 4 KB page size. For an 8 KB index page size, the best compression ratio is 2:1.
What is a page in Db2?
Pages are the unit of management within a buffer pool. The unit of I/O is one or more pages chained together. Db2 makes a getpage request operation whenever there is a need to access data in a page, either in an index or a table, such as when executing an SQL statement.
What is extent size in Db2?
An extent is a block of storage within a table space container. It represents the number of pages of data that will be written to a container before writing to the next container. The size and type of tables in the table space. Space in DMS table spaces is allocated to a table one extent at a time.
What is database page size?
DB pages can be between 512 bytes and 64K bytes in size. The size that you select must be a power of 2. You set your database’s page size using DB->set_pagesize() . Note that a database’s page size can only be selected at database creation time.
What are the mandatory components of Db2?
The 4 major components are: System services component, which supports system operation, operator communication, logging and similar functions.
What is LRG file in DB2?
Answer: The LRG file is large tablespace container. To decrease the size of file : delete the data in the table , commit an offline REORG using the LONGLOBDATA option. An Inplace REORG will not work.
How do I reduce the size of my DB2 database?
To reduce the size of an automatic storage table space:
- Formulate an ALTER TABLESPACE statement that includes a REDUCE clause. ALTER TABLESPACE table-space-name REDUCE reduction-clause.
- Run the ALTER TABLESPACE statement.
What are the mandatory components of db2?
What is dirty page in DB2?
When Db2 changes a page, the log file record is externalize to disk. This provides the “Durability” in ACID. However, the dirty page is still in the buffer pool. In this case, “dirty” means a page that has changed in memory, but that change has not yet been written out to disk.
What is the size of one extent?
Extents are the basic unit in which space is managed. An extent is eight physically contiguous pages, or 64 KB.
What is the default page size of a DB2 database?
By default, the default page size is 4096. The default can be set to one of the other possible values when the databases is created using the PAGESIZE clause of the CREATE DATABASE statement. The possible values for page size in a db2 database, no mater where it is referenced are:
How to check the size of the table in DB2?
DB2 queries to check the table size select a.CARD* (sum (b.AVGCOLLEN)+10)/1024/1024 as Tablesize_in_MB from syscat.tables as a, syscat.columns as b where a.TABNAME = b.TABNAME and b.TABNAME = ‘TABLE_NAME’ group by a.CARD
What is the default size of I/O in DB2?
The smallest unit of I/O that DB2 can handle is a page. By default, the default page size is 4096. The default can be set to one of the other possible values when the databases is created using the PAGESIZE clause of the CREATE DATABASE statement.
What is a page in Db2 LUW?
DB2 LUW – What is a Page? The logical view of a database consists of the standard objects in any RDBMS – Tables, Indexes, etc. There are a number of layers of abstraction between this and the physical hardware level, both in the OS and within DB2. The smallest unit of I/O that DB2 can handle is a page. By default, the default page size is 4096.
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