Gatherer - full redesign of connection pooling, relying on *sqlx.DB

ENV_VARIABLES.md

@@ -65,6 +65,7 @@ NB! Some variables influence multiple components. Command line parameters overri
 - **PW2_INSTANCE_LEVEL_CACHE_MAX_SECONDS** Max allowed staleness for instance level metric data shared between DBs of an instance. Affects 'continuous' host types only. Set to 0 to disable. Default: 30
 - **PW2_DIRECT_OS_STATS** Extract OS related psutil statistics not via PL/Python wrappers but directly on host, i.e. assumes "push" setup. Default: off.
 - **PW2_MIN_DB_SIZE_MB** Smaller size DBs will be ignored and not monitored until they reach the threshold. Default: 0 (no size-based limiting).
+- **PW2_MAX_PARALLEL_CONNECTIONS_PER_DB** Max parallel metric fetches per DB. Note the multiplication effect on multi-DB instances. Default: 2
 
 
 ## Web UI

pgwatch2/logparse.go

@@ -372,7 +372,7 @@ func tryDetermineLogFolder(mdb MonitoredDatabase) string {
 	sql := `select current_setting('data_directory') as dd, current_setting('log_directory') as ld`
 
 	log.Infof("[%s] Trying to determine server logs folder via SQL as host_config.logs_glob_path not specified...", mdb.DBUniqueName)
-	data, err, _ := DBExecReadByDbUniqueName(mdb.DBUniqueName, "", false, 0, sql)
+	data, err, _ := DBExecReadByDbUniqueName(mdb.DBUniqueName, "", 0, sql)
 	if err != nil {
 		log.Errorf("[%s] Failed to query data_directory and log_directory settings...are you superuser or have pg_monitor grant?", mdb.DBUniqueName)
 		return ""
@@ -390,7 +390,7 @@ func tryDetermineLogMessagesLanguage(mdb MonitoredDatabase) string {
 	sql := `select current_setting('lc_messages')::varchar(2) as lc_messages;`
 
 	log.Debugf("[%s] Trying to determine server log messages language...", mdb.DBUniqueName)
-	data, err, _ := DBExecReadByDbUniqueName(mdb.DBUniqueName, "", false, 0, sql)
+	data, err, _ := DBExecReadByDbUniqueName(mdb.DBUniqueName, "", 0, sql)
 	if err != nil {
 		log.Errorf("[%s] Failed to lc_messages settings: %s", mdb.DBUniqueName, err)
 		return ""