Small. Fast. Reliable.
Choose any three.
#define SQLITE_DETERMINISTIC 0x000000800
#define SQLITE_DIRECTONLY 0x000080000
#define SQLITE_SUBTYPE 0x000100000
#define SQLITE_INNOCUOUS 0x000200000
#define SQLITE_RESULT_SUBTYPE 0x001000000
#define SQLITE_SELFORDER1 0x002000000
These constants may be ORed together with the
preferred text encoding as the fourth argument
to sqlite3_create_function(), sqlite3_create_function16(), or
sqlite3_create_function_v2().
- SQLITE_DETERMINISTIC
-
The SQLITE_DETERMINISTIC flag means that the new function always gives
the same output when the input parameters are the same.
The abs() function is deterministic, for example, but
randomblob() is not. Functions must
be deterministic in order to be used in certain contexts such as
with the WHERE clause of partial indexes or in generated columns.
SQLite might also optimize deterministic functions by factoring them
out of inner loops.
- SQLITE_DIRECTONLY
-
The SQLITE_DIRECTONLY flag means that the function may only be invoked
from top-level SQL, and cannot be used in VIEWs or TRIGGERs nor in
schema structures such as CHECK constraints, DEFAULT clauses,
expression indexes, partial indexes, or generated columns.
The SQLITE_DIRECTONLY flag is recommended for any
application-defined SQL function
that has side-effects or that could potentially leak sensitive information.
This will prevent attacks in which an application is tricked
into using a database file that has had its schema surreptitiously
modified to invoke the application-defined function in ways that are
harmful.
Some people say it is good practice to set SQLITE_DIRECTONLY on all
application-defined SQL functions, regardless of whether or not they
are security sensitive, as doing so prevents those functions from being used
inside of the database schema, and thus ensures that the database
can be inspected and modified using generic tools (such as the CLI)
that do not have access to the application-defined functions.
- SQLITE_INNOCUOUS
-
The SQLITE_INNOCUOUS flag means that the function is unlikely
to cause problems even if misused. An innocuous function should have
no side effects and should not depend on any values other than its
input parameters. The abs() function is an example of an
innocuous function.
The load_extension() SQL function is not innocuous because of its
side effects.
SQLITE_INNOCUOUS is similar to SQLITE_DETERMINISTIC, but is not
exactly the same. The random() function is an example of a
function that is innocuous but not deterministic.
Some heightened security settings
(SQLITE_DBCONFIG_TRUSTED_SCHEMA and PRAGMA trusted_schema=OFF)
disable the use of SQL functions inside views and triggers and in
schema structures such as CHECK constraints, DEFAULT clauses,
expression indexes, partial indexes, and generated columns unless
the function is tagged with SQLITE_INNOCUOUS. Most built-in functions
are innocuous. Developers are advised to avoid using the
SQLITE_INNOCUOUS flag for application-defined functions unless the
function has been carefully audited and found to be free of potentially
security-adverse side-effects and information-leaks.
- SQLITE_SUBTYPE
-
The SQLITE_SUBTYPE flag indicates to SQLite that a function might call
sqlite3_value_subtype() to inspect the sub-types of its arguments.
This flag instructs SQLite to omit some corner-case optimizations that
might disrupt the operation of the sqlite3_value_subtype() function,
causing it to return zero rather than the correct subtype().
All SQL functions that invoke sqlite3_value_subtype() should have this
property. If the SQLITE_SUBTYPE property is omitted, then the return
value from sqlite3_value_subtype() might sometimes be zero even though
a non-zero subtype was specified by the function argument expression.
- SQLITE_RESULT_SUBTYPE
-
The SQLITE_RESULT_SUBTYPE flag indicates to SQLite that a function might call
sqlite3_result_subtype() to cause a sub-type to be associated with its
result.
Every function that invokes sqlite3_result_subtype() should have this
property. If it does not, then the call to sqlite3_result_subtype()
might become a no-op if the function is used as term in an
expression index. On the other hand, SQL functions that never invoke
sqlite3_result_subtype() should avoid setting this property, as the
purpose of this property is to disable certain optimizations that are
incompatible with subtypes.
- SQLITE_SELFORDER1
-
The SQLITE_SELFORDER1 flag indicates that the function is an aggregate
that internally orders the values provided to the first argument. The
ordered-set aggregate SQL notation with a single ORDER BY term can be
used to invoke this function. If the ordered-set aggregate notation is
used on a function that lacks this flag, then an error is raised. Note
that the ordered-set aggregate syntax is only available if SQLite is
built using the -DSQLITE_ENABLE_ORDERED_SET_AGGREGATES compile-time option.
See also lists of
Objects,
Constants, and
Functions.