log

Function

ArgDescriptionType
messageMessage to log.string (required)
dedupSuppress same message in this many seconds (default 60 sec). Use -1 to disable dedup.int64
argsAn array of elements to apply into the format string.Any
levelLevel to log at (DEFAULT, WARN, ERROR, INFO, DEBUG).string

Description

Log the message and return TRUE.

The message will be logged into the query log stream (Viewable in the Logs tab). The message parameter represents a format string that will be expanded using the args parameter list if needed.

Since log() always returns TRUE it is easy to use in a WHERE clause as a form of debugging (It is basically equivalent to the print statement of other languages).

SELECT * FROM glob(...)
WHERE log(message="Value of OSPath is %v", args=OSPath)

Deduplication

Log messages will be deduped according to the dedup parameter - each distinct format string will not be emitted more frequently than the dedup parameter (by default 60 seconds).

This makes it safe to use log() frequently without overflowing the logs stream.

SELECT * FROM range(end=_value)
WHERE log(message="Value is %v", args=_value)

Will only emit a single message due to the format string being deduped.

This property makes it useful to add progress logging to long running artifacts. The logs will be emitted every minute.

SELECT * FROM glob(...)
WHERE log(message="Processing file %v", args=OSPath)