All technological notes.
Flashback Version QueryFlashback Version QueryFlashback Version Query:
VERSIONS clause to retrieve all the versions of the rows that exist between two points in time or two SCNs.Characteristics:
transaction identifier (the VERSIONS_XID
pseudocolumn) to perform transaction mining by using LogMiner or to perform a Flashback Transaction Query. 可用于数据挖掘version query filters out such phantom(虚构的) versions because the row data remains the same. 会自动过滤虚幻的版本SELECT ... VERSION clause:
external tables, temporary tables, fixed tables, or views.
VERSIONS clause.DDL statements that change the structure of the corresponding tables.
Example:
SELECT versions_xid, salary FROM employees
VERSIONS BETWEEN TIMESTAMP <tl> and <t2>
WHERE employee id = 200;