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What is the equivalent of varchar(max) in Oracle?
CLOB?
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Oracle uses the MAX_STRING_SIZE parameter for controlling the maximum size. If the MAX_STRING_SIZE is STANDARD , then the maximum size for VARCHAR2 is 4000 bytes. In case, the MAX_STRING_SIZE is EXTENDED , the size limit for VARCHAR2 is 32767.
Storage Information : The effective maximum length of a VARCHAR is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used. Make sure you are aware of the effects of a multi-byte character set. VARCHAR(255) stores 255 characters, which may be more than 255 bytes.
varchar [ ( n | max ) ] Variable-size string data. Use n to define the string size in bytes and can be a value from 1 through 8,000 or use max to indicate a column constraint size up to a maximum storage of 2^31-1 bytes (2 GB).
Setting MAX_STRING_SIZE = EXTENDED enables the 32767 byte limit introduced in Oracle Database 12c.
Varchars are limited to 4000 characters in Oracle. Other than that, you have to use a LONG or a CLOB. Prefer CLOBs. LONGs are the older equivalent.
From this Oracle documentation:
LOBs vs. LONG and LONG RAW
LOBs are different from the older LONG and LONG RAW datatypes in many ways.
- The maximum size of a LOB is 4 Gigabytes versus 2 Gigabytes for LONG and LONG RAW.
- You can use random as well as sequential access methods on LOBs; you can only use sequential access methods on LONG and LONG RAW.
- LOBs (except NCLOBs) can be attributes of an object type that you define.
- Tables can have multiple LOB columns, but can have only one LONG or LONG RAW column.
Migration of existing LONG and LONG Raw attributes to LOBs is recommended by Oracle. Oracle plans to end support of LONG and LONG RAW in future releases. See Oracle8 Migration for more information on migration.
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