Clarification of the implementation of SQLITE_STMTSTATUS_FULLSCAN_STEP.

No logical code changes - just commenting and layout changes to improve
readability.

FossilOrigin-Name: 06b9ca32255572a699dc51f46f848d0bf01255e1

manifest

@@ -1,5 +1,8 @@
-C Clear\sthe\scolumn\scache\sbefore\spopulating\saggregate\saccumulator\sregisters.\sFix\sfo\nr\s[883034dcb5].
-D 2010-03-31T15:02:56
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA1
+
+C Clarification\sof\sthe\simplementation\sof\sSQLITE_STMTSTATUS_FULLSCAN_STEP.\nNo\slogical\scode\schanges\s-\sjust\scommenting\sand\slayout\schanges\sto\simprove\nreadability.
+D 2010-03-31T17:47:44
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 4f2f967b7e58a35bb74fb7ec8ae90e0f4ca7868b
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -211,7 +214,7 @@ F src/update.c c0dc6b75ad28b76b619042d934f337b02acee208
 F src/utf.c 1baeeac91707a4df97ccc6141ec0f808278af685
 F src/util.c 32aebf04c10e51ad3977a928b7416bed671b620b
 F src/vacuum.c b1d542c8919d4d11119f78069e1906a1ad07e0ee
-F src/vdbe.c afd58607e70bca91da8c5f9effeef0065862d0d0
+F src/vdbe.c 760a0857cdcc000759bd3a5b8e2907dd351072bc
 F src/vdbe.h 471f6a3dcec4817ca33596fe7f6654d56c0e75f3
 F src/vdbeInt.h ae1e6ba0dd3fb4a886898d2829d748be701b01f8
 F src/vdbeapi.c 74c25680046a116b24b95393914d3669c23305dc
@@ -221,7 +224,7 @@ F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1
 F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2
 F src/vtab.c 606adf51cd6d4ba51a8c6dccede06a6f7b0dd72d
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
-F src/where.c 71ef4e89715740f7af49e6f15a3fd987e040800a
+F src/where.c 8bbb34e8a836165d92a7d60b80f60be2da9615f9
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
 F test/alias.test 4529fbc152f190268a15f9384a5651bbbabc9d87
 F test/all.test 14165b3e32715b700b5f0cbf8f6e3833dda0be45
@@ -794,7 +797,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
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+U drh
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manifest.uuid

@@ -1 +1 @@
-ffc23409c7fb45dc5a8722fad26e26d207bb3213
+06b9ca32255572a699dc51f46f848d0bf01255e1

src/vdbe.c

@@ -4190,7 +4190,7 @@ case OP_Rewind: {        /* jump */
   break;
 }
 
-/* Opcode: Next P1 P2 * * *
+/* Opcode: Next P1 P2 * * P5
 **
 ** Advance cursor P1 so that it points to the next key/data pair in its
 ** table or index.  If there are no more key/value pairs then fall through
@@ -4199,9 +4199,12 @@ case OP_Rewind: {        /* jump */
 **
 ** The P1 cursor must be for a real table, not a pseudo-table.
 **
+** If P5 is positive and the jump is taken, then event counter
+** number P5-1 in the prepared statement is incremented.
+**
 ** See also: Prev
 */
-/* Opcode: Prev P1 P2 * * *
+/* Opcode: Prev P1 P2 * * P5
 **
 ** Back up cursor P1 so that it points to the previous key/data pair in its
 ** table or index.  If there is no previous key/value pairs then fall through
@@ -4209,6 +4212,9 @@ case OP_Rewind: {        /* jump */
 ** jump immediately to P2.
 **
 ** The P1 cursor must be for a real table, not a pseudo-table.
+**
+** If P5 is positive and the jump is taken, then event counter
+** number P5-1 in the prepared statement is incremented.
 */
 case OP_Prev:          /* jump */
 case OP_Next: {        /* jump */
@@ -4218,6 +4224,7 @@ case OP_Next: {        /* jump */
 
   CHECK_FOR_INTERRUPT;
   assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pOp->p5<=ArraySize(p->aCounter) );
   pC = p->apCsr[pOp->p1];
   if( pC==0 ){
     break;  /* See ticket #2273 */

src/where.c

@@ -2998,7 +2998,11 @@ static Bitmask codeOneLoopStart(
     pLevel->op = bRev ? OP_Prev : OP_Next;
     pLevel->p1 = iCur;
     pLevel->p2 = start;
-    pLevel->p5 = (pStart==0 && pEnd==0) ?1:0;
+    if( pStart==0 && pEnd==0 ){
+      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
+    }else{
+      assert( pLevel->p5==0 );
+    }
     if( testOp!=OP_Noop ){
       iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse);
       sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);