Add additional stats to postgres collector
Bug fixes and query fixes; register queries
Add support for key => value style 2 column queries
Hack to get seq_scan / idx_scan query to work properly
Exclude postgres catalog tables
Only query for a single db when multi_db is False
Fix pulling the list of databases to return all values
Set datname in metric if it's part of the query (otherwise use the connected db name)
Restrict catalog / sequences from size metrics
Add additional fields to table stat io metrics
Fix stat name for database stats to be compatible with previous postgres collector
Add legacy database connection counts (supplemented by more specific connection state metrics)
Require config value `extended` to enable additional stats
Use correct registry for basic/extended metrics
Better decorator syntax for registration of metrics
Fix metric names for compatibility
PEP8 fixes
Add comment for set_isolation_level
Add comment explaining multi_db
Fix support for underscore config argument