From ce38b176bc70e6112a8e45cc054660161a68bd60 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Tue, 4 Feb 2020 23:23:37 +0200
Subject: [PATCH] app/vmselect/promql: automatically apply `offset -step` to
 `rollup_candlestick` function in order to obtain the expected OHLC results

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/309
---
 app/vmselect/promql/eval.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/app/vmselect/promql/eval.go b/app/vmselect/promql/eval.go
index b58c8fdb07..dd32bf28f1 100644
--- a/app/vmselect/promql/eval.go
+++ b/app/vmselect/promql/eval.go
@@ -425,7 +425,7 @@ func evalRollupFunc(ec *EvalConfig, name string, rf rollupFunc, expr metricsql.E
 		if err != nil {
 			return nil, err
 		}
-		ecNew = newEvalConfig(ec)
+		ecNew = newEvalConfig(ecNew)
 		ecNew.Start -= offset
 		ecNew.End -= offset
 		if ecNew.MayCache {
@@ -435,6 +435,16 @@ func evalRollupFunc(ec *EvalConfig, name string, rf rollupFunc, expr metricsql.E
 			ecNew.End = end
 		}
 	}
+	if name == "rollup_candlestick" && len(re.Window) == 0 {
+		// Automatically apply `offset -step` to `rollup_candlestick` function
+		// in order to obtain expected OHLC results.
+		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/309#issuecomment-582113462
+		step := ecNew.Step
+		ecNew = newEvalConfig(ecNew)
+		ecNew.Start += step
+		ecNew.End += step
+		offset -= step
+	}
 	var rvs []*timeseries
 	var err error
 	if me, ok := re.Expr.(*metricsql.MetricExpr); ok {