Remove the "rowid cache" that sought to remember the largest rowid for a

table and thereby speed up OP_NewRowid.  That cache was ineffective.
Removing it results in a performance increase of 0.4%, less memory usage,
and a slightly smaller library size.

FossilOrigin-Name: 56bc5ce8958c8e6250531b4052b905d7ac993db3

manifest

@@ -1,5 +1,5 @@
-C Make\ssure\s"rowid"\scolumns\sare\scorrectly\sresolved\sin\sjoins\sbetween\snormal\ntables\sand\sWITHOUT\sROWID\stables.\s\sFix\sfor\sticket\s[c34d0557f740c45070].
+C Remove\sthe\s"rowid\scache"\sthat\ssought\sto\sremember\sthe\slargest\srowid\sfor\sa\ntable\sand\sthereby\sspeed\sup\sOP_NewRowid.\s\sThat\scache\swas\sineffective.\nRemoving\sit\sresults\sin\sa\sperformance\sincrease\sof\s0.4%,\sless\smemory\susage,\nand\sa\sslightly\ssmaller\slibrary\ssize.
-D 2014-02-12T14:43:52.953
+D 2014-02-12T21:31:12.616
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -166,9 +166,9 @@ F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
 F src/backup.c a729e63cf5cd1829507cb7b8e89f99b95141bb53
 F src/bitvec.c 19a4ba637bd85f8f63fc8c9bae5ade9fb05ec1cb
 F src/btmutex.c 976f45a12e37293e32cae0281b15a21d48a8aaa7
-F src/btree.c 7b2c3cd16deedff7f4904f2e871e7b77328b9872
+F src/btree.c 97020a77cb53fb9d8e7f172d489b8f92af1d1b82
-F src/btree.h a61ddebc78c66795a2b93181321a116746302cc9
+F src/btree.h 9e0f97c01b972f779eb7655cfb4f8727fd6dc26f
-F src/btreeInt.h f038e818bfadf75afbd09819ed93c26a333d39e0
+F src/btreeInt.h 0be66063468a520e4d66b80c7a1dc26d04ee6ea4
 F src/build.c 13b9d82181d95af7b00ec8a8e1304bac096432d4
 F src/callback.c 174e3c8656bc29f91d710ab61550d16eea34be98
 F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
@@ -280,7 +280,7 @@ F src/update.c a7df6fffce6bfedc578fda6136dd33e34a63f8ee
 F src/utf.c 6fc6c88d50448c469c5c196acf21617a24f90269
 F src/util.c c46c90459ef9bdc0c6c73803cf4c55425b4771cf
 F src/vacuum.c 3728d74919d4fb1356f9e9a13e27773db60b7179
-F src/vdbe.c e5c87476d717aebef5dafceab11417ebf2730554
+F src/vdbe.c 3f0872b12ec3fc24ee540f8bb09de181ddad6d8d
 F src/vdbe.h e6c4c610fcabad4fa80ebb1efc6822a9367e2b26
 F src/vdbeInt.h 5286af9067cabdb8ba57b87c0c988a931be6c6c8
 F src/vdbeapi.c 5bc41aaea448a7fc250902c418f1795859be3820
@@ -1153,7 +1153,7 @@ F tool/vdbe-compress.tcl 0cf56e9263a152b84da86e75a5c0cdcdb7a47891
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P 0a8bcbbd4e11a60923736b2be9b1ce83ea2263fb
+P 5d01426ddfb2d47c57f93f71378594e637424be0
-R ece7306a4645e7a68a79bfe14ec94970
+R 0f58210f2a6ea71dc58155d3b9fc47e4
 U drh
-Z 89db972fa80a38407f6b56a44d53bf78
+Z 0cd8ad70eddd970bc8638e6270cc29ff

manifest.uuid

@@ -1 +1 @@
-5d01426ddfb2d47c57f93f71378594e637424be0
+56bc5ce8958c8e6250531b4052b905d7ac993db3

src/btree.c

@@ -3632,7 +3632,6 @@ static int btreeCursor(
   }
   pBt->pCursor = pCur;
   pCur->eState = CURSOR_INVALID;
-  pCur->cachedRowid = 0;
   return SQLITE_OK;
 }
 int sqlite3BtreeCursor(
@@ -3673,36 +3672,6 @@ void sqlite3BtreeCursorZero(BtCursor *p){
   memset(p, 0, offsetof(BtCursor, iPage));
 }
 
-/*
-** Set the cached rowid value of every cursor in the same database file
-** as pCur and having the same root page number as pCur.  The value is
-** set to iRowid.
-**
-** Only positive rowid values are considered valid for this cache.
-** The cache is initialized to zero, indicating an invalid cache.
-** A btree will work fine with zero or negative rowids.  We just cannot
-** cache zero or negative rowids, which means tables that use zero or
-** negative rowids might run a little slower.  But in practice, zero
-** or negative rowids are very uncommon so this should not be a problem.
-*/
-void sqlite3BtreeSetCachedRowid(BtCursor *pCur, sqlite3_int64 iRowid){
-  BtCursor *p;
-  for(p=pCur->pBt->pCursor; p; p=p->pNext){
-    if( p->pgnoRoot==pCur->pgnoRoot ) p->cachedRowid = iRowid;
-  }
-  assert( pCur->cachedRowid==iRowid );
-}
-
-/*
-** Return the cached rowid for the given cursor.  A negative or zero
-** return value indicates that the rowid cache is invalid and should be
-** ignored.  If the rowid cache has never before been set, then a
-** zero is returned.
-*/
-sqlite3_int64 sqlite3BtreeGetCachedRowid(BtCursor *pCur){
-  return pCur->cachedRowid;
-}
-
 /*
 ** Close a cursor.  The read lock on the database file is released
 ** when the last cursor is closed.
@@ -6986,11 +6955,17 @@ int sqlite3BtreeInsert(
   rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
   if( rc ) return rc;
 
-  /* If this is an insert into a table b-tree, invalidate any incrblob 
-  ** cursors open on the row being replaced (assuming this is a replace
-  ** operation - if it is not, the following is a no-op).  */
   if( pCur->pKeyInfo==0 ){
+    /* If this is an insert into a table b-tree, invalidate any incrblob 
+    ** cursors open on the row being replaced */
     invalidateIncrblobCursors(p, nKey, 0);
+
+    /* If the cursor is currently on the last row and we are appending a
+    ** new row onto the end, set the "loc" to avoid an unnecessary btreeMoveto()
+    ** call */
+    if( pCur->validNKey && nKey>0 && pCur->info.nKey==nKey-1 ){
+      loc = -1;
+    }
   }
 
   if( !loc ){
@@ -7060,8 +7035,8 @@ int sqlite3BtreeInsert(
   ** row without seeking the cursor. This can be a big performance boost.
   */
   pCur->info.nSize = 0;
-  pCur->validNKey = 0;
   if( rc==SQLITE_OK && pPage->nOverflow ){
+    pCur->validNKey = 0;
     rc = balance(pCur);
 
     /* Must make sure nOverflow is reset to zero even if the balance()

src/btree.h

@@ -182,8 +182,6 @@ const void *sqlite3BtreeKeyFetch(BtCursor*, u32 *pAmt);
 const void *sqlite3BtreeDataFetch(BtCursor*, u32 *pAmt);
 int sqlite3BtreeDataSize(BtCursor*, u32 *pSize);
 int sqlite3BtreeData(BtCursor*, u32 offset, u32 amt, void*);
-void sqlite3BtreeSetCachedRowid(BtCursor*, sqlite3_int64);
-sqlite3_int64 sqlite3BtreeGetCachedRowid(BtCursor*);
 
 char *sqlite3BtreeIntegrityCheck(Btree*, int *aRoot, int nRoot, int, int*);
 struct Pager *sqlite3BtreePager(Btree*);

src/btreeInt.h

@@ -500,7 +500,6 @@ struct BtCursor {
   Pgno *aOverflow;          /* Cache of overflow page locations */
 #endif
   Pgno pgnoRoot;            /* The root page of this tree */
-  sqlite3_int64 cachedRowid; /* Next rowid cache.  0 means not valid */
   CellInfo info;            /* A parse of the cell we are pointing at */
   i64 nKey;        /* Size of pKey, or last integer key */
   void *pKey;      /* Saved key that was cursor's last known position */

src/vdbe.c

@@ -3834,8 +3834,6 @@ case OP_NewRowid: {           /* out2-prerelease */
 #endif
 
     if( !pC->useRandomRowid ){
-      v = sqlite3BtreeGetCachedRowid(pC->pCursor);
-      if( v==0 ){
       rc = sqlite3BtreeLast(pC->pCursor, &res);
       if( rc!=SQLITE_OK ){
         goto abort_due_to_error;
@@ -3884,9 +3882,6 @@ case OP_NewRowid: {           /* out2-prerelease */
       pMem->u.i = v;
     }
 #endif
-
-      sqlite3BtreeSetCachedRowid(pC->pCursor, v<MAX_ROWID ? v+1 : 0);
-    }
     if( pC->useRandomRowid ){
       /* IMPLEMENTATION-OF: R-07677-41881 If the largest ROWID is equal to the
       ** largest possible integer (9223372036854775807) then the database
@@ -4020,7 +4015,6 @@ case OP_InsertInt: {
   }else{
     nZero = 0;
   }
-  sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
   rc = sqlite3BtreeInsert(pC->pCursor, 0, iKey,
                           pData->z, pData->n, nZero,
                           (pOp->p5 & OPFLAG_APPEND)!=0, seekResult
@@ -4082,7 +4076,6 @@ case OP_Delete: {
   rc = sqlite3VdbeCursorMoveto(pC);
   if( NEVER(rc!=SQLITE_OK) ) goto abort_due_to_error;
 
-  sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
   rc = sqlite3BtreeDelete(pC->pCursor);
   pC->cacheStatus = CACHE_STALE;