Small performance improvement in the btreeOverwriteCell() routine.

FossilOrigin-Name: df5ea47130d275e9fa1bd6aa8d55f1d5e136cba30ba13b7ede22224aa7f78919

manifest

@@ -1,5 +1,5 @@
-C Add\ssome\sdocs\sexplaining\sa\sparticular\spiece\sof\s[ae0196d86ee8].\sNo\scode\schanges.
+C Small\sperformance\simprovement\sin\sthe\sbtreeOverwriteCell()\sroutine.
-D 2023-01-02T20:52:46.522
+D 2023-01-03T15:11:01.142
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -584,7 +584,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 6ffb0a22c19e2f9110be0964d0731d2ef1c67b5f7fabfbaeb7b9dabc4b7740ca
-F src/btree.c 2f794c217e52fdf4322bf37ee7778331b4d93aed2c00b5d67f914c0239a9edcc
+F src/btree.c cc4d9e293a22d08b27f12f04a325f798b60093943d8929de702f533c18c54a4e
 F src/btree.h 49da925329574798be3cbb745a49d069a9e67c99900d8a0d04b1e934d60394ea
 F src/btreeInt.h 88ad499c92b489afedbfefc3f067c4d15023ec021afe622db240dc9d2277cfa5
 F src/build.c c55ab6d1b089ceef57160e840f05f692955ac90944c3d04fcf01d97fd7bfd08d
@@ -2067,8 +2067,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P ae0196d86ee8ca424b5ef5a43c32988f4ab5131ea146669bc1467e31a2384901
+P 7f96803c1cbd0633367173ab0a67a8b301b9e0746e460c50d506b536c15db0a0
-R 468770ff1d6e218ca1a386beedb2179e
+R 10289e6f8e31034fa806339dcdadfd2f
-U stephan
+U drh
-Z d6968ffff8c57917bdc920258d7e0b7f
+Z 4e108d77c081298b7689d1eafc6b59e1
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-7f96803c1cbd0633367173ab0a67a8b301b9e0746e460c50d506b536c15db0a0
+df5ea47130d275e9fa1bd6aa8d55f1d5e136cba30ba13b7ede22224aa7f78919

src/btree.c

@@ -8914,9 +8914,13 @@ static int btreeOverwriteContent(
 
 /*
 ** Overwrite the cell that cursor pCur is pointing to with fresh content
-** contained in pX.
+** contained in pX.  In this variant, pCur is pointing to an overflow
+** cell.
 */
-static int btreeOverwriteCell(BtCursor *pCur, const BtreePayload *pX){
+static SQLITE_NOINLINE int btreeOverwriteOverflowCell(
+  BtCursor *pCur,                     /* Cursor pointing to cell to ovewrite */
+  const BtreePayload *pX              /* Content to write into the cell */
+){
   int iOffset;                        /* Next byte of pX->pData to write */
   int nTotal = pX->nData + pX->nZero; /* Total bytes of to write */
   int rc;                             /* Return code */
@@ -8925,16 +8929,12 @@ static int btreeOverwriteCell(BtCursor *pCur, const BtreePayload *pX){
   Pgno ovflPgno;                      /* Next overflow page to write */
   u32 ovflPageSize;                   /* Size to write on overflow page */
 
-  if( pCur->info.pPayload + pCur->info.nLocal > pPage->aDataEnd
+  assert( pCur->info.nLocal<nTotal );  /* pCur is an overflow cell */
-   || pCur->info.pPayload < pPage->aData + pPage->cellOffset
+
-  ){
-    return SQLITE_CORRUPT_BKPT;
-  }
   /* Overwrite the local portion first */
   rc = btreeOverwriteContent(pPage, pCur->info.pPayload, pX,
                              0, pCur->info.nLocal);
   if( rc ) return rc;
-  if( pCur->info.nLocal==nTotal ) return SQLITE_OK;
 
   /* Now overwrite the overflow pages */
   iOffset = pCur->info.nLocal;
@@ -8964,6 +8964,29 @@ static int btreeOverwriteCell(BtCursor *pCur, const BtreePayload *pX){
   return SQLITE_OK;    
 }
 
+/*
+** Overwrite the cell that cursor pCur is pointing to with fresh content
+** contained in pX.
+*/
+static int btreeOverwriteCell(BtCursor *pCur, const BtreePayload *pX){
+  int nTotal = pX->nData + pX->nZero; /* Total bytes of to write */
+  MemPage *pPage = pCur->pPage;       /* Page being written */
+
+  if( pCur->info.pPayload + pCur->info.nLocal > pPage->aDataEnd
+   || pCur->info.pPayload < pPage->aData + pPage->cellOffset
+  ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  if( pCur->info.nLocal==nTotal ){
+    /* The entire cell is local */
+    return btreeOverwriteContent(pPage, pCur->info.pPayload, pX,
+                                 0, pCur->info.nLocal);
+  }else{
+    /* The cell contains overflow content */
+    return btreeOverwriteOverflowCell(pCur, pX);
+  }
+}
+
 
 /*
 ** Insert a new record into the BTree.  The content of the new record