---
name: "pmSeriesInstances"
section: "3"
platform: "linux"
package: "pcp"
version: "7.2.2-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/pmSeriesDescs"
---

# pmSeriesInstances(3)

fast, scalable time series metadata

Part of [pmSeriesDescs(3)](/pmSeriesDescs/3.md).

## NAME

**pmSeriesDescs**, **pmSeriesLabels**, **pmSeriesLabelValues**, **pmSeriesInstances**, **pmSeriesMetrics**, **pmSeriesSources** - fast, scalable time series metadata

## C SYNOPSIS

**#include \<pcp/pmwebapi.h\>**

**int pmSeriesDescs(pmSeriesSettings \****sp***,** **int** *count***,** **sds \****series***,** **void \****arg***);**\
 **int pmSeriesLabels(pmSeriesSettings \****sp***,** **int** *count***,** **sds \****series***,** **void \****arg***);**\
 **int pmSeriesLabelValues(pmSeriesSettings \****sp***,** **int** *count***,** **sds \****labels***,** **void \****arg***);**\
 **int pmSeriesInstances(pmSeriesSettings \****sp***,** **int** *count***,** **sds \****series***,** **void \****arg***);**\
 **int pmSeriesMetrics(pmSeriesSettings \****sp***,** **int** *count***,** **sds \****series***,** **void \****arg***);**\
 **int pmSeriesSources(pmSeriesSettings \****sp***,** **int** *count***,** **sds \****series***,** **void \****arg***);**

**cc ... -lpcp\_web**

## DESCRIPTION

Each performance metric and data source forming part of the Performance Co-Pilot (PCP) fast, scalable time series service has certain properties (metadata) associated with it. These properties can be queried using the interfaces described here.

This functionality is provided through asynchronous APIs, which function in an event-driven fashion where callbacks are invoked for each metadata structure being returned.

As a general pattern, all interfaces in these APIs that need to invoke callbacks provided by the calling program (see [**pmSeriesSetup**(3)](/pmSeriesSetup/3.md)) will take an opaque (void \* pointer) parameter, *arg*. This pointer will be passed through unchanged and is typically used to access a data structure maintaining state within the calling program.

With a couple of exceptions, these interfaces tend to operate in one of two modes. Firstly, one invocation is available to query metadata for a specific (non-zero) *count* of time *series*. A second, (zero) *count*, mode returns all available metadata of that type, across all time series.

In order to retrieve metric descriptor information for one or more time series, the **pmSeriesDescs** interface is used. For each valid *series* identifier provided, a callback will be invoked providing the metric units, semantics, and type as well as other identifiers associated with it (pmID, InDom and source identifier). When this call is issued with a zero value for *count*, It is an error to pass a zero or negative value of *count* into this interface.

To extract label names and values, the **pmSeriesLabels** interface is used. With a non-zero value for *count* valid *series* identifiers, this routine will invoke a callback once for each label name and once for each label name:value pair, for labels associated with those time series. If called with a *count* of zero, this interface will return (via the label name callback) all label names that have observed to date - not associated with specific time series. The **pmSeriesLabelValues** interface is comparable to this latter mode, except will return all label values that have been observed to date for the given array of *labels* names (not associated with any specific time series identifiers).

**pmSeriesInstances** can be used to find metadata about instance domains and instance identifiers associated with a given (non-zero) *count* of time *series* identifiers. If a zero value is passed for *count* then all instance names observed to date will be returned.

**pmSeriesMetrics** can be used to find metric names associated with a given (non-zero) *count* of time *series* identifiers. If a zero value is passed for *count* then all metric names observed to date will be returned.

**pmSeriesSources** can be used to find metadata about the source of metrics - that is, host names and archive file paths. If a zero value is passed for *count* then all metric sources observed to date will be returned.

## DIAGNOSTICS

Where these functions return a status code, this is always zero on success. On failure a negative PMAPI error code is returned.

## SEE ALSO

[**pmproxy**(1)](/pmproxy/1.md), [**pmlogger**(1)](/pmlogger/1.md), [**pmseries**(1)](/pmseries/1.md), [**pmSeriesQuery**(3)](/pmSeriesQuery/3.md), [**pmSeriesSetup**(3)](/pmSeriesSetup/3.md), [**PMAPI**(3)](/PMAPI/3.md) and [**PMWEBAPI**(3)](/PMWEBAPI/3.md).