From 437f8d27eb4a20412b8509dc55706542ae52c094 Mon Sep 17 00:00:00 2001
From: Anton Alkin <anton.alkin@cern.ch>
Date: Thu, 15 Jan 2026 14:43:39 +0100
Subject: [PATCH] DPL Analysis: fix for slice index builder resetting its
 caches in a wrong order

---
 Framework/Core/src/IndexBuilderHelpers.cxx | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Framework/Core/src/IndexBuilderHelpers.cxx b/Framework/Core/src/IndexBuilderHelpers.cxx
index d7231f72cbee8..0943dea42169c 100644
--- a/Framework/Core/src/IndexBuilderHelpers.cxx
+++ b/Framework/Core/src/IndexBuilderHelpers.cxx
@@ -161,14 +161,14 @@ SliceBuilder::SliceBuilder(std::shared_ptr<arrow::ChunkedArray> source, arrow::M
 
 void SliceBuilder::reset(std::shared_ptr<arrow::ChunkedArray> source)
 {
+  mValues = nullptr;
+  mCounts = nullptr;
+  mListBuilder->Reset();
+  mValuePos = 0;
   static_cast<ChunkedArrayIterator*>(this)->reset(source);
   if (!preSlice().ok()) {
     throw framework::runtime_error("Cannot pre-slice the source for slice-index building");
   }
-  mListBuilder->Reset();
-  mValues = nullptr;
-  mCounts = nullptr;
-  mValuePos = 0;
 }
 
 bool SliceBuilder::find(int idx)