Updating date in oracle
On the client, you can use either a large or a small file.
Adding the conversion operator may, however, slow down queries and disable usage of indexes on the Oracle Database supplies multiple versions of time zone files, and there are two types of file associated with each one: a large file, which contains all the time zones defined in the database, and a small file, which contains only the most commonly used time zones.The values of these fields determine the value of the data type.The fields that apply to all Oracle Database datetime and interval data types are: initialization parameters.The time zone offset is the difference (in hours and minutes) between local time and UTC (Coordinated Universal Time, formerly Greenwich Mean Time).
Specify the as follows: data stored in the database is normalized to the database time zone, and the time zone offset is not stored as part of the column data.
Note that some regions, such as Brazil and Israel, that update their Daylight Saving Transition dates frequently and at irregular periods, are particularly susceptible to time zone adjustment issues. For example, you can use them to calculate a moving average of stock prices. The following is one example of specifying an interval of 123 years and 2 months. If you change the values in the initialization parameter file, you must restart the instance for the change to take effect.