Question: What does
the nls_length_semantics parameter do? Can you show an
example using nls_length_semantics?
Answer: The nls_length_semantics
parameter enables you to create CHAR and VARCHAR2 columns,
using either byte or character length semantics. The default
for nls_length_semantics is "byte". You MUST create a new
database with nls_length_semantics=byte because scripts such
as catalog.sql must use the byte setting.
Oracle notes this about the nls_length_semantics
"The session-level value of
nls_length_semantics specifies the default length
semantics to use for VARCHAR2 and CHAR table columns . . .
This default may be overridden by the
explicit length semantics qualifiers BYTE and CHAR in
column, attribute, and variable definitions.
The instance-level value of
nls_length_semantics provides a default for the
session-level value if
nls_length_semantics it is not set explicitly by the
database client through the
nls_length_semantics client environment variable
(does not apply to JDBC Thin clients, or the ALTER SESSION
WARNING: Oracle strongly
recommends that you NOT set NLS_LENGTH_SEMANTICS=CHAR in the
init.ora or spfile. Doing this may cause many existing
installation scripts to unexpectedly create columns with
character length semantics, resulting in runtime errors,
including buffer overflows.
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