From c0c5754b7a54f180ca90e8e8e5ed71154fd8f7ea Mon Sep 17 00:00:00 2001
From: hjxilinx <hjxilinx@163.com>
Date: Wed, 8 Jan 2020 17:35:07 +0800
Subject: [PATCH] help to prevent current data in file from causing TDengine
 crashed while min/max function is invoked.

---
 src/client/src/tscFunctionImpl.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/client/src/tscFunctionImpl.c b/src/client/src/tscFunctionImpl.c
index d317006e48..29f6f2dd26 100644
--- a/src/client/src/tscFunctionImpl.c
+++ b/src/client/src/tscFunctionImpl.c
@@ -909,7 +909,17 @@ static void minMax_function(SQLFunctionCtx *pCtx, char *pOutput, int32_t isMin,
       tval = &pCtx->preAggVals.max;
       index = pCtx->preAggVals.maxIndex;
     }
-
+  
+    /**
+     * NOTE: work around the bug caused by invalid pre-calculated function.
+     * Here the selectivity + ts will not return correct value.
+     *
+     * The following codes of 3 lines will be removed later.
+     */
+    if (index < 0 || index >= pCtx->size + pCtx->startOffset) {
+      index = 0;
+    }
+    
     TSKEY key = pCtx->ptsList[index];
 
     if (pCtx->inputType >= TSDB_DATA_TYPE_TINYINT && pCtx->inputType <= TSDB_DATA_TYPE_BIGINT) {
-- 
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