influxdata/telegraf

run postgres_extensible query across multiple databases

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#3219 opened on Sep 11, 2017

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area/postgresqlfeature requesthelp wantedsize/l

Description

Feature Request

Opening a feature request kicks off a discussion.

Proposal:

The postgres_extensible plugin should support a way of running the same query across multiple databases. The configuration should allow running across all discovered databases, or a filtered list.

Current behavior:

No such feature

Desired behavior:

Such a feature

Use case: [Why is this important (helps with prioritizing requests)]

Postgres provides a lot of data though what it calls "system catalogs", which are really tables within each database. Thus to use them you have to connect to that database. Instead of having to know which databases are present, and then having to hard-code those databases in the telegraf config on each server, it would be nice if we could push out the same telegraf config to all servers.

Contributor guide

Tech stack
gopostgresql
Domain
backenddatabase
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
Go programmingTelegraf plugin architecturePostgreSQL system catalogs
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Examine the existing postgres extensible plugin in plugins/inputs/postgresql extensible/ to understand how single database queries are handled. The feature requires adding an option to specify multiple database names or a discovery mechanism, then executing the query per database. Review any linked PRs or comments for design constraints. Start by implementing a simple comma separated list of databases in the plugin configuration.