DBA_HIST_PARAMETER

DBA_HIST_PARAMETER displays historical information about the initialization parameters that were in effect for the instance. This view contains snapshots of V$SYSTEM_PARAMETER.

Column	Datatype	NULL	Description
`SNAP_ID`	`NUMBER`	`NOT NULL`	Unique snapshot ID
`DBID`	`NUMBER`	`NOT NULL`	Database ID for the snapshot
`INSTANCE_NUMBER`	`NUMBER`	`NOT NULL`	Instance number for the snapshot
`PARAMETER_HASH`	`NUMBER`	`NOT NULL`	Parameter hash
`PARAMETER_NAME`	`VARCHAR2(64)`	`NOT NULL`	Name of the parameter
`VALUE`	`VARCHAR2(512)`		Parameter value for the session (if modified within the session); otherwise, the instance-wide parameter value
`ISDEFAULT`	`VARCHAR2(9)`		Indicates whether the parameter is set to the default value (`TRUE`) or the parameter value was specified in the parameter file (`FALSE`)
`ISMODIFIED`	`VARCHAR2(10)`		Indicates whether the parameter has been modified after instance startup: `MODIFIED` - Parameter has been modified with `ALTER SESSION` `SYSTEM_MOD` - Parameter has been modified with `ALTER SYSTEM` (which causes all the currently logged in sessions' values to be modified) `FALSE` - Parameter has not been modified after instance startup
`CON_DBID`	`NUMBER`		The database ID of the PDB for the sampled session
`CON_ID`	`NUMBER`		The ID of the container that `CON_DBID` identifies. Possible values include: `0`: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs. `1`: This value is used for rows containing data that pertain to only the root n: Where n is the applicable container ID for the rows containing data