From ca84805cfcd1c53b02feac3a59c339f45df6129a Mon Sep 17 00:00:00 2001
From: Hongze Cheng <hzcheng@taosdata.com>
Date: Tue, 6 Dec 2022 17:22:58 +0800
Subject: [PATCH] fix interpolation corner case

---
 source/dnode/vnode/src/tsdb/tsdbUtil.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/source/dnode/vnode/src/tsdb/tsdbUtil.c b/source/dnode/vnode/src/tsdb/tsdbUtil.c
index 55aea3a6d6..79007a49a0 100644
--- a/source/dnode/vnode/src/tsdb/tsdbUtil.c
+++ b/source/dnode/vnode/src/tsdb/tsdbUtil.c
@@ -1105,8 +1105,13 @@ void tBlockDataGetColData(SBlockData *pBlockData, int16_t cid, SColData **ppColD
   int32_t ridx = pBlockData->nColData - 1;
 
   while (lidx <= ridx) {
-    int32_t midx = lidx + (ridx - lidx) * (cid - pBlockData->aColData[lidx].cid) /
-                              (pBlockData->aColData[ridx].cid - pBlockData->aColData[lidx].cid);
+    int32_t midx;
+    if (lidx == ridx) {
+      midx = lidx;
+    } else {
+      midx = lidx + (ridx - lidx) * (cid - pBlockData->aColData[lidx].cid) /
+                        (pBlockData->aColData[ridx].cid - pBlockData->aColData[lidx].cid);
+    }
     SColData *pColData = tBlockDataGetColDataByIdx(pBlockData, midx);
     int32_t   c = (pColData->cid == cid) ? 0 : ((pColData->cid > cid) ? 1 : -1);