Implement optimized exists query in InfluxDB

This avoids returning too much results when using standard listSeries

scripts/lua/modules/timeseries/drivers/influxdb.lua

@@ -1053,12 +1053,9 @@ local function processListSeriesResult(data, schema, tags_filter, wildcard_tags)
   return res
 end
 
-function driver:listSeries(schema, tags_filter, wildcard_tags, start_time)
-  if schema.options.influx_internal_query then
-    -- internal metrics always exist
-    return {{}} -- exists
-  end
+-- ##############################################
 
+function driver:listSeries(schema, tags_filter, wildcard_tags, start_time)
   local query = makeListSeriesQuery(schema, tags_filter, wildcard_tags, start_time)
   local url = self.url
   local data = influx_query(url .. "/query?db=".. self.db, query, self.username, self.password)
@@ -1068,6 +1065,24 @@ end
 
 -- ##############################################
 
+function driver:exists(schema, tags_filter, wildcard_tags)
+  if schema.options.influx_internal_query then
+    -- internal metrics always exist
+    return(true)
+  end
+
+  -- Ignore wildcard_tags to avoid exessive points returned due to group by
+  wildcard_tags = {}
+
+  local query = makeListSeriesQuery(schema, tags_filter, wildcard_tags, 0)
+  local url = self.url
+  local data = influx_query(url .. "/query?db=".. self.db, query, self.username, self.password)
+
+  return(not table.empty(processListSeriesResult(data, schema, tags_filter, wildcard_tags)))
+end
+
+-- ##############################################
+
 function driver:listSeriesBatched(batch)
   local max_batch_size = 30
   local url = self.url

scripts/lua/modules/timeseries/ts_utils_core.lua

@@ -569,15 +569,9 @@ end
 
 -- ##############################################
 
-local function list_series(schema_name, tags_filter, start_time, batched)
-  local schema = ts_utils.getSchema(schema_name)
+local function getWildcardTags(schema, tags_filter)
   tags_filter = tags_filter or {}
 
-  if not schema then
-    traceError(TRACE_ERROR, TRACE_CONSOLE, "Schema not found: " .. schema_name)
-    return nil
-  end
-
   local wildcard_tags = {}
   local filter_tags = {}
 
@@ -594,19 +588,7 @@ local function list_series(schema_name, tags_filter, start_time, batched)
     end
   end
 
-  if not batched then
-    local driver = ts_utils.getQueryDriver()
-
-    if not driver then
-      return nil
-    end
-
-    ts_common.clearLastError()
-
-    return driver:listSeries(schema, filter_tags, wildcard_tags, start_time)
-  else
-    return schema, filter_tags, wildcard_tags
-  end
+  return filter_tags, wildcard_tags
 end
 
 -- ##############################################
@@ -617,7 +599,21 @@ end
 --! @param start_time time filter. Only timeseries updated after start_time will be returned.
 --! @return a (possibly empty) list of tags values for the matching timeseries on success, nil on error.
 function ts_utils.listSeries(schema_name, tags_filter, start_time)
-  return list_series(schema_name, tags_filter, start_time, false --[[ not batched ]])
+  local schema = ts_utils.getSchema(schema_name)
+  local driver = ts_utils.getQueryDriver()
+
+  if(not schema) then
+    traceError(TRACE_ERROR, TRACE_CONSOLE, "Schema not found: " .. schema_name)
+    return nil
+  end
+
+  if(not driver) then
+    return nil
+  end
+
+  local filter_tags, wildcard_tags = getWildcardTags(schema, tags_filter)
+
+  return driver:listSeries(schema, filter_tags, wildcard_tags, start_time)
 end
 
 -- ##############################################
@@ -631,12 +627,15 @@ local pending_listseries_batch = {}
 --! @return nil on error, otherwise a number is returned, indicating the item id into the batch
 --! @note Call ts_utils.getBatchedListSeriesResult() to get the batch responses
 function ts_utils.batchListSeries(schema_name, tags_filter, start_time)
-  local schema, filter_tags, wildcard_tags = list_series(schema_name, tags_filter, start_time, true --[[ batched ]])
+  local schema = ts_utils.getSchema(schema_name)
 
-  if not schema then
+  if(not schema) then
+    traceError(TRACE_ERROR, TRACE_CONSOLE, "Schema not found: " .. schema_name)
     return nil
   end
 
+  local filter_tags, wildcard_tags = getWildcardTags(schema, tags_filter)
+
   pending_listseries_batch[#pending_listseries_batch + 1] = {
     schema = schema,
     start_time = start_time,
@@ -681,12 +680,31 @@ end
 
 -- ##############################################
 
---! @brief A shortcut for ts_utils.listSeries to verify timeseries existance.
+--! @brief Verify timeseries existance.
 --! @param schema_name the schema identifier.
 --! @param tags_filter a list of filter tags. Tags which are not specified are considered wildcard.
 --! @return true if the specified series exist, false otherwise.
 function ts_utils.exists(schema_name, tags_filter)
-  return not table.empty(ts_utils.listSeries(schema_name, tags_filter, 0))
+  local driver = ts_utils.getQueryDriver()
+
+  if not driver then
+    return nil
+  end
+
+  if(driver.exists == nil) then
+    -- No "exists" implementation found, use listSeries fallback
+    return not table.empty(ts_utils.listSeries(schema_name, tags_filter, 0))
+  end
+
+  local schema = ts_utils.getSchema(schema_name)
+
+  if(not schema) then
+    traceError(TRACE_ERROR, TRACE_CONSOLE, "Schema not found: " .. schema_name)
+    return nil
+  end
+
+  local filter_tags, wildcard_tags = getWildcardTags(schema, tags_filter)
+  return driver:exists(schema, filter_tags, wildcard_tags)
 end
 
 -- ##############################################