Reference · Database

db.system

db.system(str) -> null | error(str)

What it does

Names the system database: where Quillo keeps its own tables, the scheduled jobs (_quillo_jobs), the decisions of db.atomic (_quillo_atomic) and the calls a service answered. Calls made later stay with the work, in the program's database or the tenant's, and only go here when there is neither. Without it they go to the program's database, or, when that is one per tenant, to $QUILLO_SYSTEM_DB or a SQLite file quillo-system.db next to the program. Several servers of one program share one system database, so give them a server URL. It gives null when the database is open and an error value when it is not.

Examples

print(db.system("system.db"))print(db.query("select 1 as still_the_program_database"))

null[{ still_the_program_database: 1 }]

db.open("data/{tenant}.db")          // a database per tenant: jobs cannot live theredb.system(env("SYSTEM_DB_URL"))      // one for every server of the program

Edge cases

• It keeps Quillo's tables apart from the program's even when there is one database.
• The program's db calls do not go to it: it is not another db.open.
• A file that cannot be opened is an error value; the program goes on.
• Calling it again with the same target is harmless.

print(db.system("system.db"), db.system("system.db"))print(db.system("nope/dir/system.db") | is_err)

null nulltrue

Errors

A path that cannot be opened is an error value; a target that is not a string is a runtime error.

print(db.system(1))

line 1: `db.system` expects a path or a database URL

Chaining

Called once, at the top of the program, after db.open:

print("system.db" | db.system)

null

See also

db.open, db.atomic, db.tenants, schedule

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