PG Exporter v0.5.0

VonngAuthor of PG Exporter and Pigsty, working on PostgreSQL infrastructure and monitoring.

Exporter changes

• Used nFPM to build RPM and DEB packages.
• Added column.default to substitute a value for NULL.
• Added column.scale to scale numeric values, such as microseconds to seconds.
• Fixed /stat output.
• Added the pgsty/pg_exporter Docker image.

Collector changes

• Converted time metrics to seconds in pg_wal, pg_query, pg_db, pg_bgwriter, pg_ssl, and pgbouncer_stat.
• Moved pg_class metrics into pg_table and pg_index.
• Enabled pg_table_size by default.