+ History: this configuration value was introduced in notmuch 0.32.
+
+ Default: For compatibility with older configurations, the value of
+ database.path is used if **database.mail\_root** is unset.
+
+**database.backup_dir**
+ Directory to store tag dumps when upgrading database.
+
+ History: this configuration value was introduced in notmuch 0.32.
+
+ Default: A sibling directory of the Xapian database called
+ `backups`.
+
+**database.hook_dir**
+ Directory containing hooks run by notmuch commands. See
+ :any:`notmuch-hooks(5)`.
+
+ History: this configuration value was introduced in notmuch 0.32.
+
+ Default: See HOOKS, below.
+
+**database.autocommit**
+
+ How often to commit transactions to disk. `0` means wait until
+ command completes, otherwise an integer `n` specifies to commit to
+ disk after every `n` completed transactions.
+
+ History: this configuration value was introduced in notmuch 0.33.