Storage

DlmpDbValue

Type: nil|boolean|integer|number|string

DlmpDbParams

Positions 1..n, where n is the n field (table.pack) or the highest index; a nil in between is NULL.

Type: DlmpDbValue[]

DlmpDbRow

One row by column name; a NULL column is absent. Use AS to rename duplicate columns.

Type: table<string, DlmpDbValue>

DlmpDb

The resource's own storage namespace. The server keeps one per resource and applies the resource's migrations ([storage.migrations] sqlite = ["migrations/sqlite/001_init.sql", ...], in order, each once; a migration must not be edited after it has run) before its scripts run. No resource can access another's. SQL is the dialect of the server's backend (SQLite: ? placeholders, RETURNING, ON CONFLICT); a statement may read and change rows, but the schema changes only in a migration.

Every call queues its request and returns immediately: true, or nil, err when 256 requests are already waiting. The result reaches the callback in a later server step, in request order; a stopped resource receives no callbacks, but its queued writes still run. A malformed argument (a table or non-UTF-8 string parameter, SQL over 64 KiB, more than 256 parameters) raises an error. Limits: 10 000 rows and 16 MiB per result, 1 MiB per value, 5 s per statement or transaction.

DlmpDb.query

Runs one statement and passes its rows to callback(rows), or calls callback(nil, err).

Parameters

• sql string
• params (optional) DlmpDbParams
• callback fun(rows: DlmpDbRow[]|nil, err: string|nil)

Returns ok true|nil, err string|nil

DlmpDb.exec

Runs one statement that returns no rows and calls callback(changed_rows) or callback(nil, err). Without a callback, a failure is written to the server log.

Parameters

• sql string
• params (optional) DlmpDbParams
• callback (optional) fun(changes: integer|nil, err: string|nil)

Returns ok true|nil, err string|nil

DlmpDb.transaction

Runs 1..256 statements as one transaction (all or none), then calls callback(true) or callback(nil, err), where err gives the number of the failed statement. No Lua runs between statements, so put conditions in the SQL (WHERE money >= ?).

Parameters

• statements { [1]: string, [2]: DlmpDbParams|nil }[]
• callback (optional) fun(ok: true|nil, err: string|nil)

Returns ok true|nil, err string|nil