Simplification of the OP_Column logic for the case of rows with overflow.

FossilOrigin-Name: f73678038d8fc399c1ca55230ae45962007c909c

manifest

@@ -1,5 +1,5 @@
-C Remove\san\sunused\sparameter\sfrom\ssqlite3VdbeIdxRowid().\s\sThis\sis\scosmetic\nonly\sas\sthe\sC-compiler\soptimizers\swere\salready\somitting\sthis\sparameter\son\namalgamation\sbuilds.
-D 2014-09-16T14:55:08.312
+C Simplification\sof\sthe\sOP_Column\slogic\sfor\sthe\scase\sof\srows\swith\soverflow.
+D 2014-09-16T18:22:44.852
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in cf57f673d77606ab0f2d9627ca52a9ba1464146a
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -288,13 +288,13 @@ F src/update.c 729f6f18fc27740591d085e1172cebe311144bf0
 F src/utf.c 77abb5e6d27f3d236e50f7c8fff1d00e15262359
 F src/util.c 4006c01772bd8d8ac4306d523bbcee41d3e392d8
 F src/vacuum.c 59f03f92bcff57faa6a8ca256eb29ccddfb0614a
-F src/vdbe.c ae07ee84667c190d31946ae31c2fc63a3aa81a32
+F src/vdbe.c ff1b0b4f41355ba207bdc691b1017e7642f42c6b
 F src/vdbe.h 09f5b4e3719fa454f252322b1cdab5cf1f361327
 F src/vdbeInt.h dc1743de339f5556cc6687219cf8727ad0d35f72
 F src/vdbeapi.c 4d2aa56efa1b4a010012466bf8e97dbf179081a6
 F src/vdbeaux.c 79ce140ee79ecc7638eac070b48f1d24bbf9653c
 F src/vdbeblob.c 848238dc73e93e48432991bb5651bf87d865eca4
-F src/vdbemem.c 4d1e1398be24f85805196c20a80699be0699a9ca
+F src/vdbemem.c 8abc122ce5359a120196e0825dca9a08a787aff6
 F src/vdbesort.c 09efa5e5098d1a159cd21f588eb118e4fe87cfde
 F src/vdbetrace.c 16d39c1ef7d1f4a3a7464bea3b7b4bdd7849c415
 F src/vtab.c 019dbfd0406a7447c990e1f7bd1dfcdb8895697f
@@ -1198,7 +1198,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 8239c35aedd583af79505378bb7dbb78346a3f45
-R 8e31ee1c1cfa56f2cb381e2e177d1a9b
+P a10a6bba4963761b490b7243b388dcc920c4cfed
+R e7cf963c2745f47a3657ad38e9817c1f
 U drh
-Z 717af3cbede201cebaf3af532573dee2
+Z 153a841014a3e255f6703a490d77aa20

manifest.uuid

@@ -1 +1 @@
-a10a6bba4963761b490b7243b388dcc920c4cfed
+f73678038d8fc399c1ca55230ae45962007c909c

src/vdbe.c

@@ -2449,37 +2449,23 @@ case OP_Column: {
           && ((t>=12 && (t&1)==0) || (pOp->p5 & OPFLAG_TYPEOFARG)!=0))
      || (len = sqlite3VdbeSerialTypeLen(t))==0
     ){
-      /* Content is irrelevant for the typeof() function and for
-      ** the length(X) function if X is a blob.  So we might as well use
-      ** bogus content rather than reading content from disk.  NULL works
-      ** for text and blob and whatever is in the payloadSize64 variable
-      ** will work for everything else.  Content is also irrelevant if
-      ** the content length is 0. */
-      zData = t<=13 ? (u8*)&payloadSize64 : 0;
-      sMem.zMalloc = 0;
+      /* Content is irrelevant for
+      **    1. the typeof() function,
+      **    2. the length(X) function if X is a blob, and
+      **    3. if the content length is zero.
+      ** So we might as well use bogus content rather than reading
+      ** content from disk.  NULL will work for the value for strings
+      ** and blobs and whatever is in the payloadSize64 variable
+      ** will work for everything else. */
+      sqlite3VdbeSerialGet(t<=13 ? (u8*)&payloadSize64 : 0, t, pDest);
     }else{
-      memset(&sMem, 0, sizeof(sMem));
-      sqlite3VdbeMemMove(&sMem, pDest);
       rc = sqlite3VdbeMemFromBtree(pCrsr, aOffset[p2], len, !pC->isTable,
-                                   &sMem);
+                                   pDest);
       if( rc!=SQLITE_OK ){
         goto op_column_error;
       }
-      zData = (u8*)sMem.z;
-    }
-    sqlite3VdbeSerialGet(zData, t, pDest);
-    /* If we dynamically allocated space to hold the data (in the
-    ** sqlite3VdbeMemFromBtree() call above) then transfer control of that
-    ** dynamically allocated space over to the pDest structure.
-    ** This prevents a memory copy. */
-    if( sMem.zMalloc ){
-      assert( sMem.z==sMem.zMalloc );
-      assert( VdbeMemDynamic(pDest)==0 );
-      assert( (pDest->flags & (MEM_Blob|MEM_Str))==0 || pDest->z==sMem.z );
-      pDest->flags &= ~(MEM_Ephem|MEM_Static);
-      pDest->flags |= MEM_Term;
-      pDest->z = sMem.z;
-      pDest->zMalloc = sMem.zMalloc;
+      sqlite3VdbeSerialGet((const u8*)pDest->z, t, pDest);
+      pDest->flags &= ~MEM_Ephem;
     }
   }
   pDest->enc = encoding;

src/vdbemem.c

@@ -885,8 +885,11 @@ int sqlite3VdbeMemSetStr(
 ** key is true to get the key or false to get data.  The result is written
 ** into the pMem element.
 **
-** The pMem structure is assumed to be uninitialized.  Any prior content
-** is overwritten without being freed.
+** The pMem object must have been initialized.  This routine will use
+** pMem->zMalloc to hold the content from the btree, if possible.  New
+** pMem->zMalloc space will be allocated if necessary.  The calling routine
+** is responsible for making sure that the pMem object is eventually
+** destroyed.
 **
 ** If this routine fails for any reason (malloc returns NULL or unable
 ** to read from the disk) then the pMem is left in an inconsistent state.