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SQLITE3_VTAB_NOCHANGE(3)   Library Functions Manual   SQLITE3_VTAB_NOCHANGE(3)

NAME
     sqlite3_vtab_nochange - determine if virtual table column access is for
     UPDATE

SYNOPSIS
     #include <sqlite3.h>

     int
     sqlite3_vtab_nochange(sqlite3_context*);

DESCRIPTION
     If the sqlite3_vtab_nochange(X) routine is called within the xColumn
     method of a virtual table, then it might return true if the column is
     being fetched as part of an UPDATE operation during which the column
     value will not change.  The virtual table implementation can use this
     hint as permission to substitute a return value that is less expensive to
     compute and that the corresponding xUpdate method understands as a "no-
     change" value.

     If the xColumn method calls sqlite3_vtab_nochange() and finds that the
     column is not changed by the UPDATE statement, then the xColumn method
     can optionally return without setting a result, without calling any of
     the sqlite3_result_xxxxx() interfaces.  In that case,
     sqlite3_value_nochange(X) will return true for the same column in the
     xUpdate method.

     The sqlite3_vtab_nochange() routine is an optimization.  Virtual table
     implementations should continue to give a correct answer even if the
     sqlite3_vtab_nochange() interface were to always return false.  In the
     current implementation, the sqlite3_vtab_nochange() interface does always
     returns false for the enhanced UPDATE FROM statement.

IMPLEMENTATION NOTES
     These declarations were extracted from the interface documentation at
     line 9716.

     SQLITE_API int sqlite3_vtab_nochange(sqlite3_context*);

SEE ALSO
     sqlite3_result_blob(3)

NetBSD 10.99                    August 24, 2023                   NetBSD 10.99