Provide the BTREE_SEEK_EQ hint to the b-tree layer.

FossilOrigin-Name: e750830f1e61160c0c67e35b13e50b35a95b50e1

src/btree.c

@@ -7480,7 +7480,8 @@ static int balance(BtCursor *pCur){
           ** pSpace buffer passed to the latter call to balance_nonroot().
           */
           u8 *pSpace = sqlite3PageMalloc(pCur->pBt->pageSize);
-          rc = balance_nonroot(pParent, iIdx, pSpace, iPage==1, pCur->hints);
+          rc = balance_nonroot(pParent, iIdx, pSpace, iPage==1,
+                               pCur->hints&BTREE_BULKLOAD);
           if( pFree ){
             /* If pFree is not NULL, it points to the pSpace buffer used 
             ** by a previous call to balance_nonroot(). Its contents are
@@ -9143,14 +9144,23 @@ int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
 }
 
 /*
-** set the mask of hint flags for cursor pCsr. Currently the only valid
-** values are 0 and BTREE_BULKLOAD.
+** set the mask of hint flags for cursor pCsr.
 */
 void sqlite3BtreeCursorHints(BtCursor *pCsr, unsigned int mask){
-  assert( mask==BTREE_BULKLOAD || mask==0 );
+  assert( mask==BTREE_BULKLOAD || mask==BTREE_SEEK_EQ || mask==0 );
   pCsr->hints = mask;
 }
 
+#ifdef SQLITE_DEBUG
+/*
+** Return true if the cursor has a hint specified.  This routine is
+** only used from within assert() statements
+*/
+int sqlite3BtreeCursorHasHint(BtCursor *pCsr, unsigned int mask){
+  return (pCsr->hints & mask)!=0;
+}
+#endif
+
 /*
 ** Return true if the given Btree is read-only.
 */

src/btree.h

@@ -152,8 +152,18 @@ int sqlite3BtreeNewDb(Btree *p);
 /*
 ** Values that may be OR'd together to form the second argument of an
 ** sqlite3BtreeCursorHints() call.
+**
+** The BTREE_BULKLOAD flag is set on index cursors when the index is going
+** to be filled with content that is already in sorted order.
+**
+** The BTREE_SEEK_EQ flag is set on cursors that will get OP_SeekGE or
+** OP_SeekLE opcodes for a range search, but where the range of entries
+** selected will all have the same key.  In other words, the cursor will
+** be used only for equality key searches.
+**
 */
-#define BTREE_BULKLOAD 0x00000001
+#define BTREE_BULKLOAD 0x00000001  /* Used to full index in sorted order */
+#define BTREE_SEEK_EQ  0x00000002  /* EQ seeks only - no range seeks */
 
 int sqlite3BtreeCursor(
   Btree*,                              /* BTree containing table to open */
@@ -199,6 +209,9 @@ void sqlite3BtreeIncrblobCursor(BtCursor *);
 void sqlite3BtreeClearCursor(BtCursor *);
 int sqlite3BtreeSetVersion(Btree *pBt, int iVersion);
 void sqlite3BtreeCursorHints(BtCursor *, unsigned int mask);
+#ifdef SQLITE_DEBUG
+int sqlite3BtreeCursorHasHint(BtCursor*, unsigned int mask);
+#endif
 int sqlite3BtreeIsReadonly(Btree *pBt);
 int sqlite3HeaderSizeBtree(void);
 

src/sqliteInt.h

@@ -2692,7 +2692,8 @@ struct AuthContext {
 #define OPFLAG_LENGTHARG     0x40    /* OP_Column only used for length() */
 #define OPFLAG_TYPEOFARG     0x80    /* OP_Column only used for typeof() */
 #define OPFLAG_BULKCSR       0x01    /* OP_Open** used to open bulk cursor */
-#define OPFLAG_P2ISREG       0x02    /* P2 to OP_Open** is a register number */
+#define OPFLAG_SEEKEQ        0x02    /* OP_Open** cursor uses EQ seek only */
+#define OPFLAG_P2ISREG       0x04    /* P2 to OP_Open** is a register number */
 #define OPFLAG_PERMUTE       0x01    /* OP_Compare: use the permutation */
 
 /*

src/vdbe.c

@@ -3237,12 +3237,12 @@ case OP_SetCookie: {       /* in3 */
 case OP_ReopenIdx: {
   VdbeCursor *pCur;
 
-  assert( pOp->p5==0 );
+  assert( pOp->p5==0 || pOp->p5==OPFLAG_SEEKEQ );
   assert( pOp->p4type==P4_KEYINFO );
   pCur = p->apCsr[pOp->p1];
   if( pCur && pCur->pgnoRoot==(u32)pOp->p2 ){
     assert( pCur->iDb==pOp->p3 );      /* Guaranteed by the code generator */
-    break;
+    goto open_cursor_set_hints;
   }
   /* If the cursor is not currently open or is open on a different
   ** index, then fall through into OP_OpenRead to force a reopen */
@@ -3258,8 +3258,8 @@ case OP_OpenWrite: {
   VdbeCursor *pCur;
   Db *pDb;
 
-  assert( (pOp->p5&(OPFLAG_P2ISREG|OPFLAG_BULKCSR))==pOp->p5 );
-  assert( pOp->opcode==OP_OpenWrite || pOp->p5==0 );
+  assert( (pOp->p5&(OPFLAG_P2ISREG|OPFLAG_BULKCSR|OPFLAG_SEEKEQ))==pOp->p5 );
+  assert( pOp->opcode==OP_OpenWrite || pOp->p5==0 || pOp->p5==OPFLAG_SEEKEQ );
   assert( p->bIsReader );
   assert( pOp->opcode==OP_OpenRead || pOp->opcode==OP_ReopenIdx
           || p->readOnly==0 );
@@ -3322,14 +3322,17 @@ case OP_OpenWrite: {
   pCur->pgnoRoot = p2;
   rc = sqlite3BtreeCursor(pX, p2, wrFlag, pKeyInfo, pCur->pCursor);
   pCur->pKeyInfo = pKeyInfo;
-  assert( OPFLAG_BULKCSR==BTREE_BULKLOAD );
-  sqlite3BtreeCursorHints(pCur->pCursor, (pOp->p5 & OPFLAG_BULKCSR));
-
   /* Set the VdbeCursor.isTable variable. Previous versions of
   ** SQLite used to check if the root-page flags were sane at this point
   ** and report database corruption if they were not, but this check has
   ** since moved into the btree layer.  */  
   pCur->isTable = pOp->p4type!=P4_KEYINFO;
+
+open_cursor_set_hints:
+  assert( OPFLAG_BULKCSR==BTREE_BULKLOAD );
+  assert( OPFLAG_SEEKEQ==BTREE_SEEK_EQ );
+  sqlite3BtreeCursorHints(pCur->pCursor,
+                          (pOp->p5 & (OPFLAG_BULKCSR|OPFLAG_SEEKEQ)));
   break;
 }
 
@@ -3590,6 +3593,22 @@ case OP_SeekGT: {       /* jump, in3 */
 #ifdef SQLITE_DEBUG
   pC->seekOp = pOp->opcode;
 #endif
+
+  /* For a cursor with the BTREE_SEEK_EQ hint, only the OP_SeekGE and
+  ** OP_SeekLE opcodes are allowed, and these must be immediately followed
+  ** by an OP_IdxGT or OP_IdxLT opcode, respectively, with the same key.
+  */
+#ifdef SQLITE_DEBUG
+  if( sqlite3BtreeCursorHasHint(pC->pCursor, BTREE_SEEK_EQ) ){
+    assert( pOp->opcode==OP_SeekGE || pOp->opcode==OP_SeekLE );
+    assert( pOp[1].opcode==OP_IdxLT || pOp[1].opcode==OP_IdxGT );
+    assert( pOp[1].p1==pOp[0].p1 );
+    assert( pOp[1].p2==pOp[0].p2 );
+    assert( pOp[1].p3==pOp[0].p3 );
+    assert( pOp[1].p4.i==pOp[0].p4.i );
+  }
+#endif
+ 
   if( pC->isTable ){
     /* The input value in P3 might be of any type: integer, real, string,
     ** blob, or NULL.  But it needs to be an integer before we can do

src/where.c

@@ -6801,6 +6801,12 @@ WhereInfo *sqlite3WhereBegin(
       if( op ){
         sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb);
         sqlite3VdbeSetP4KeyInfo(pParse, pIx);
+        if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0
+         && (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0
+         && (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0
+        ){
+          sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); /* Hint to COMDB2 */
+        }
         VdbeComment((v, "%s", pIx->zName));
       }
     }