Fix invalid upsampling due to missing points in composed charts

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

@@ -496,7 +496,9 @@ local function influx2Series(schema, tstart, tend, tags, options, data, time_ste
 
    -- Fill the missing points at the end
   while((tend - next_t) >= 0) do
-    if(next_t > last_ts) then
+    -- NOTE: fill_series is required for composed charts. In such case,
+    -- not filling the serie would result into an incorrect upsampling
+    if((not options.fill_series) and (next_t > last_ts)) then
       -- skip values exceeding the last point
       break
     end

scripts/lua/modules/timeseries/ts_utils_core.lua

@@ -282,6 +282,7 @@ function ts_utils.getQueryOptions(overrides)
     initial_point = false,   -- add an extra initial point, not accounted in statistics but useful for drawing graphs
     with_series = false,    -- in topk query, if true, also get top items series data
     no_timeout = true,      -- do not abort queries automatically by default
+    fill_series = false,    -- if true, filling missing points is required
   }, overrides or {})
 end
 
@@ -480,7 +481,7 @@ function ts_utils.queryTopk(schema_name, tags, tstart, tend, options)
     top_items.series = {}
 
     -- Query the top items data
-    local options = table.merge(query_options, {calculate_stats = false})
+    local options = table.merge(query_options, {calculate_stats = false, fill_series = true})
     local count = 0
     local step = nil
     local raw_step = nil