1 概念说明
The maximum size of the VARCHAR2, NVARCHAR2, and RAW data types has been increased from 4,000 to 32,767 bytes.
Increasing the allotted size for these data types allows users to store more information in character data types before switching to large objects (LOBs). This is especially useful for brief textual data types and the capabilities to build indexes on these types of columns.
VARCHAR2、NVARCHAR2和原始数据类型的最大大小从4,000增加到32,767字节。
增加这些数据类型的分配大小允许用户在切换到大型对象(lob)之前存储更多字符数据类型的信息。这对于简短的文本数据类型和在这些类型的列上构建索引的功能特别有用。
Beginning with Oracle Database 12c, you can specify a maximum size of 32767 bytes for the VARCHAR2, NVARCHAR2, and RAW data types. You can control whether your database supports this new maximum size by setting the initialization parameter MAX_STRING_SIZE as follows:
If MAX_STRING_SIZE = STANDARD, then the size limits for releases prior to Oracle Database 12c apply: 4000 bytes for the VARCHAR2 and NVARCHAR2 data types, and 2000 bytes for the RAW data type. This is the default.
If MAX_STRING_SIZE = EXTENDED, then the size limit is 32767 bytes for the VARCHAR2, NVARCHAR2, and RAW data types.
从Oracle Database 12c开始，您可以为VARCHAR2、NVARCHAR2和原始数据类型指定最大大小为32767字节。您可以通过设置初始化参数MAX_STRING_SIZE来控制数据库是否支持这个新的最大大小:
如果MAX_STRING_SIZE = STANDARD，那么在Oracle数据库12c之前释放的大小限制适用于:VARCHAR2和NVARCHAR2数据类型的4000字节，以及原始数据类型的2000字节。这是默认的。
如果MAX_STRING_SIZE = EXTENDED，那么大小限制为VARCHAR2、NVARCHAR2和原始数据类型的32767字节。The maximum size of the VARCHAR2,
