experimental.join() function
experimental.join() is subject to change at any time.
experimental.join() joins two streams of tables on the group key and _time column.
Deprecated
experimental.join() is deprecated in favor of join.time().
The join package provides support
for multiple join methods.
Use the fn parameter to map new output tables using values from input tables.
Note: To join streams of tables with different fields or measurements,
use group() or drop() to remove _field and _measurement from the
group key before joining.
Function type signature
(fn: (left: A, right: B) => C, left: stream[A], right: stream[B]) => stream[C] where A: Record, B: Record, C: Record
For more information, see Function type signatures.
Parameters
left
(Required) First of two streams of tables to join.
right
(Required) Second of two streams of tables to join.
fn
(Required)
Function with left and right arguments that maps a new output record
using values from the left and right input records.
The return value must be a record.
Examples
Join two streams of tables
import "array"
import "experimental"
left =
array.from(
rows: [
{_time: 2021-01-01T00:00:00Z, _field: "temp", _value: 80.1},
{_time: 2021-01-01T01:00:00Z, _field: "temp", _value: 80.6},
{_time: 2021-01-01T02:00:00Z, _field: "temp", _value: 79.9},
{_time: 2021-01-01T03:00:00Z, _field: "temp", _value: 80.1},
],
)
right =
array.from(
rows: [
{_time: 2021-01-01T00:00:00Z, _field: "temp", _value: 75.1},
{_time: 2021-01-01T01:00:00Z, _field: "temp", _value: 72.6},
{_time: 2021-01-01T02:00:00Z, _field: "temp", _value: 70.9},
{_time: 2021-01-01T03:00:00Z, _field: "temp", _value: 71.1},
],
)
experimental.join(
left: left,
right: right,
fn: (left, right) =>
({left with lv: left._value, rv: right._value, diff: left._value - right._value}),
)
Join two streams of tables with different fields and measurements
import "experimental"
s1 =
from(bucket: "example-bucket")
|> range(start: -1h)
|> filter(fn: (r) => r._measurement == "foo" and r._field == "bar")
|> group(columns: ["_time", "_measurement", "_field", "_value"], mode: "except")
s2 =
from(bucket: "example-bucket")
|> range(start: -1h)
|> filter(fn: (r) => r._measurement == "baz" and r._field == "quz")
|> group(columns: ["_time", "_measurement", "_field", "_value"], mode: "except")
experimental.join(
left: s1,
right: s2,
fn: (left, right) => ({left with bar_value: left._value, quz_value: right._value}),
)
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