How can you determine the size of a table in Redshift?
To ascertain the size of a table in Redshift, a specific command is utilized. This command is SELECT ``table'', size, tbl_rows FROM SVV_TABLE_INFO. In this command, the 'table' column refers to the table name, 'size' refers to the table size in MB, and 'tbl_rows' is the total number of rows in the table.
- SVV_TABLE_INFO: This is a Redshift systems table that provides information about user-defined tables in a Redshift database. This table is only visible to superusers.
- Table Size: The size column in the command represents the size of the table in megabytes.
- Table Rows: The tbl_rows column in the command indicates the total number of rows in the table.
What is the role of SVV_TABLE_INFO in Redshift?
SVV_TABLE_INFO is a system table in Redshift that contains information about user-defined tables in a Redshift database. It is only visible to superusers and is used to retrieve various details about a table, including its size and the total number of rows.
- User-defined tables: These are tables created by users in the Redshift database. SVV_TABLE_INFO provides detailed information about these tables.
- Superuser visibility: Only superusers can view the SVV_TABLE_INFO table. This is a security measure to prevent unauthorized access to table information.
- Table details: SVV_TABLE_INFO can be used to retrieve various details about a table, such as its size and the total number of rows.
How can you use the table_info.sql script in Redshift?
The table_info.sql script can be used in Redshift to return a list of all user tables in the system, along with information about each table. The 'mbytes' column in the script indicates the total size of each table in megabytes.
- User Tables: The script returns a list of all user tables in the system, providing a comprehensive overview of the database structure.
- Table Information: Along with the list of tables, the script also provides detailed information about each table.
- Mbytes column: This column in the script indicates the total size of each table in megabytes, helping users understand the space utilization of each table.
SELECT "table", size, tbl_rows
FROM SVV_TABLE_INFO
