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as

Input Stack:
replacement: String
original: String
expr: TimeSeriesExpr
 ⇨ Output Stack:
TimeSeriesExpr
 
 

Rename a tag key to use an alternative name. This operator creates a mapping from one tag key to another, which is essential for performing mathematical operations between time series that use different tag keys to represent the same conceptual dimension.

Parameters

  • expr: The time series expression to apply tag key renaming to
  • original: The existing tag key name to be renamed
  • replacement: The new tag key name to use

Common Use Cases

Binary Math Operations

When performing operations like addition, subtraction, or division between time series from different sources, tag keys must match for proper alignment. In most cases, the data should be cleaned up so renaming is not necessary. If that is not possible, then the :as operator can rename one side to align the keys.

IPC Metrics Comparison

A common scenario involves comparing server and client perspectives of the same interactions. The common IPC metrics illustrate this pattern:

  • Server side: Groups by nf.app (the server application)
  • Client side: Groups by ipc.server.app (the server being called)

Both represent the same application, but use different tag keys.

Examples

Basic tag key renaming for legend display:

BeforeAfter
name,sps,:eq,
(,nf.cluster,),:by

name,sps,:eq,
(,nf.cluster,),:by,
nf.cluster,c,:as,
$c,:legend

Mathematical Operation Alignment

# Server-side requests per second (grouped by nf.app):
name,server.requests,:eq,(,nf.app,),:by

# Client-side requests per second (grouped by ipc.server.app):
name,client.requests,:eq,(,ipc.server.app,),:by,ipc.server.app,nf.app,:as

# Now both can be combined since they share the same tag key:
name,server.requests,:eq,(,nf.app,),:by,
name,client.requests,:eq,(,ipc.server.app,),:by,ipc.server.app,nf.app,:as,
:sub
  • :legend - Custom legend text with variable substitution
  • :s - Search and replace on legend strings
  • :by - Group time series by tag keys
  • :add / :sub / :mul / :div - Mathematical operations requiring aligned tag keys

See Also