Pragmas
In LiteDB v5, pragmas are variables that can alter the behavior of a datafile. They are stored in the header of the datafile.

Name			Read-only																Data type							Description																																				Default value
--------------- ----------------------------------------------------------------------- ----------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------- -----------------------------
USER_VERSION	no																		int									Reserved for version control by the user. Does not affect the behavior of the datafile.																	0
COLLATION		yes (can be changed with a rebuild)										string (internally stored as int)	Check Collation.																																		CurrentCulture and IgnoreCase
TIMEOUT			no																		int									Maximum amount of time (in seconds) that the engine waits for a shared resouce to be unlocked.															60
  等待鎖定 60 秒.
LIMIT_SIZE		no																		long								Maximum size (in bytes) that the datafile can grow to. Cannot be smaller than the current datafile size. Cannot be smaller than 4 pages (32768 bytes).	long.MaxValue
  long.MaxValue = 9,223,372,036,854,775,807 bytes = 9,223,372 TB   
UTC_DATE		no																		bool								If false, dates are converted to local time on retrieval. Storage format is not affected (always in UTC).												false
CHECKPOINT		no																		int									Maximum number of pages to be stored in the log before a soft checkpoint. If set to 0, auto-checkpoint and shutdown checkpoint are disabled.			1000
--------------- ----------------------------------------------------------------------- ----------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------- -----------------------------

Examples
select pragmas from $database; returns the pragmas in the current datafile

pragma USER_VERSION = 1; sets USER_VERSION to 1

pragma UTC_DATE = true; sets UTC_DATE to true

Rebuild Options
Rebuild options are used to configure a rebuild.

Name	Data type	Description	Default value
collation	string	Check Collation.	null (will use CurrentCulture and IgnoreCase if null)
password	string	Defines the password for an encrypted datafile.	null (datafile will not be encrypted)
If the rebuild command is issued without options, both are assumed to be null.

Rebuilds are also useful to defragment a datafile, making it smaller and faster to access.

rebuild; rebuilds the database with the default collation and no password
rebuild {"collation": "en-GB/IgnoreCase"}; rebuilds the datafile with the en-GB culture and case-insensitive string comparison
rebuild {"collation": "pt-BR/None", "password" : "1234"}; rebuilds the datafile with the pt-BR culture, case-sensitive string comparison and sets the password to “1234”