[Metricbeat] [PostgreSQL] module [database] metricset - wrong mapping for blk_read_time and blk_write_time

[fkalinowski]

• Version: metricbeat 7.11 + PostgreSQL 11
• Operating System: k8s v1.18.9+k3s1 under k3OS v0.11.1
• Discuss Forum URL: https://discuss.elastic.co/t/metricbeat-module-postgresql-wrong-mapping-of-blk-read-time-and-blk-write-time/270722
• Steps to Reproduce:

1. in Metricbeat: enable PostgreSQL module
2. in PostgreSQL: enable track_io_timing via postgresql.conf --> uncomment or add track_io_timing = on
3. in Metricbeat: connect the Metricbeat instance with PostgreSQL module to your PostgreSQL database + enable database metricset
4. check that fields postgresql.database.blocks.time.read.ms and postgresql.database.blocks.time.write.ms are missing while expected (due to step n°2).

• Detailed description:

According to beats/metricbeat/module/postgresql/database/data.go, the following fields are mapped as Integer:

	    "blocks": s.Object{
...
		"time": s.Object{
			"read":  s.Object{"ms": c.Int("blk_read_time")},
			"write": s.Object{"ms": c.Int("blk_write_time")},
		},
...

But according to the official PostgreSQL documentation, theses columns are double precision - see PostgreSQL: Documentation: 9.2: The Statistics Collector

Due to this wrong mapping, once the "track_io_timing" feature is enabled at PostgreSQL side then the fields postgresql.database.blocks.time.read.ms and postgresql.database.blocks.time.write.ms are always missing (more than probably due to an error while mapping).

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)