NAME¶

pmFetchArchive, pmFetchHighResArchive - get performance metric values directly from archives

C SYNOPSIS¶

#include <pcp/pmapi.h>

int pmFetchArchive(pmResult **result);
int pmFetchHighResArchive(pmHighResResult **result);

cc ... -lpcp

DESCRIPTION¶

The pmFetchArchive and pmFetchHighResArchive APIs are variants of the pmFetch(3) and pmFetchHighRes(3) interfaces that may only be used when the current Performance Metrics Application Programming Interface (PMAPI) context is associated with a set of archives.

The result is instantiated with all of the metrics (and instances) from the next archive record, consequently there is no notion of a list of desired metrics, and the instance profile of the PMAPI context is ignored.

pmFetchArchive and pmFetchHighResArchive may return a result in which numpmid is zero. This is a <mark> record that indicates a temporal discontinuity in the time series of performance metrics. This can happen at the boundary between archives in a set or if the archive associated with the current PMAPI context was created using pmlogextract(1) to concatenate two or more PCP archives, and the <mark> record marks a point in time between the end of one input archive and the start of the next input archive.

It is expected that pmFetchArchive and pmFetchHighResArchive will be used to create utilities that scan sets of archives, while the more common access to the archives would be via the pmFetch and pmFetchHighRes interfaces.

To skip records within the set of archives, use pmSetMode(3) or pmSetModeHighRes(3) to change the collection time within the current PMAPI context, then call either pmFetchArchive or pmFetchHighResArchive.

Note that the result returned by both pmFetchArchive and pmFetchHighResArchive is dynamically allocated, and must be released using either pmFreeResult(3) or pmFreeHighResResult(3), but not free(3). See pmFetch(3), pmFetchHighRes(3), pmFreeResult(3) and pmFreeHighResResult(3) for further details.

Both pmFetchArchive and pmFetchHighResArchive returns zero on success.

DIAGNOSTICS¶

PM_ERR_NOTARCHIVE

the current PMAPI context is not associated with a set of archives

SEE ALSO¶

PMAPI(3), pmFetchHighRes(3), pmSetModeHighRes(3), pmFreeHighResResult(3), pmFetch(3), pmFreeResult(3), pmNewContext(3), pmSetMode(3) and pmTrimNameSpace(3).