diff --git a/source/libs/executor/src/scanoperator.c b/source/libs/executor/src/scanoperator.c
index b567d46a4a..2b95fa8e4d 100644
--- a/source/libs/executor/src/scanoperator.c
+++ b/source/libs/executor/src/scanoperator.c
@@ -3578,7 +3578,7 @@ int32_t startRowIdSort(STableMergeScanInfo *pInfo) {
   pageSize *= 2;
   int numOfTables = pInfo->tableEndIndex - pInfo->tableStartIndex + 1;                                                       
   int32_t memSize = MIN(pageSize * numOfTables, 512 * 1024 * 1024);
-  int32_t code = createDiskbasedBuf(&pSort->pExtSrcRowsBuf, pageSize * 2, memSize, "tms-ext-src-block", tsTempDir);
+  int32_t code = createDiskbasedBuf(&pSort->pExtSrcRowsBuf, pageSize, memSize, "tms-ext-src-block", tsTempDir);
   dBufSetPrintInfo(pSort->pExtSrcRowsBuf);
   return code;
 }