SQLite

void sqlite3BackupRestart(sqlite3_backup *);
void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
void sqlite3AnalyzeFunctions(void);
int sqlite3Stat4ProbeSetValue(Parse*,Index*,UnpackedRecord**,Expr*,u8,int,int*);
int sqlite3Stat4ValueFromExpr(Parse*, Expr*, u8, sqlite3_value**);
void sqlite3Stat4ProbeFree(UnpackedRecord*);
int sqlite3Stat4Column(sqlite3*, const void*, int, int, sqlite3_value**);
#endif

/*
** The interface to the LEMON-generated parser
*/
void *sqlite3ParserAlloc(void*(*)(size_t));
void sqlite3ParserFree(void*, void(*)(void*));

  int i;
  FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);
  FuncDef *aFunc = (FuncDef*)&GLOBAL(FuncDef, aAnalyzeTableFuncs);
  for(i=0; i<ArraySize(aAnalyzeTableFuncs); i++){
    sqlite3FuncDefInsert(pHash, &aFunc[i]);
  }
}

static int stat4ValueFromExpr(
  Parse *pParse,                  /* Parse context */
  Expr *pExpr,                    /* The expression to extract a value from */
  u8 affinity,                    /* Affinity to use */
  struct ValueNewStat4Ctx *pAlloc,/* How to allocate space */
  sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
){
  int rc = SQLITE_OK;
  sqlite3_value *pVal = 0;
  sqlite3 *db = pParse->db;

  /* Skip over any TK_COLLATE nodes */
  pExpr = sqlite3ExprSkipCollate(pExpr);

  if( !pExpr ){
    pVal = valueNew(db, pAlloc);
    if( pVal ){
      sqlite3VdbeMemSetNull((Mem*)pVal);
    }
  }else if( pExpr->op==TK_VARIABLE
        || NEVER(pExpr->op==TK_REGISTER && pExpr->op2==TK_VARIABLE)
  ){
    Vdbe *v;
    int iBindVar = pExpr->iColumn;
    sqlite3VdbeSetVarmask(pParse->pVdbe, iBindVar);
    if( (v = pParse->pReprepare)!=0 ){
      pVal = valueNew(db, pAlloc);
      if( pVal ){
        rc = sqlite3VdbeMemCopy((Mem*)pVal, &v->aVar[iBindVar-1]);
        if( rc==SQLITE_OK ){
          sqlite3ValueApplyAffinity(pVal, affinity, ENC(db));
        }
        pVal->db = pParse->db;
      }
    }
  }else{
    rc = valueFromExpr(db, pExpr, ENC(db), affinity, &pVal, pAlloc);
  }

  assert( pVal==0 || pVal->db==db );
  *ppVal = pVal;
  return rc;
}

/*
** This function is used to allocate and populate UnpackedRecord 
** structures intended to be compared against sample index keys stored 
** in the sqlite_stat4 table.
**
** A single call to this function attempts to populates field iVal (leftmost 

  Index *pIdx,                    /* Index being probed */
  UnpackedRecord **ppRec,         /* IN/OUT: Probe record */
  Expr *pExpr,                    /* The expression to extract a value from */
  u8 affinity,                    /* Affinity to use */
  int iVal,                       /* Array element to populate */
  int *pbOk                       /* OUT: True if value was extracted */
){
  int rc;
  sqlite3_value *pVal = 0;

  struct ValueNewStat4Ctx alloc;


  alloc.pParse = pParse;
  alloc.pIdx = pIdx;
  alloc.ppRec = ppRec;
  alloc.iVal = iVal;



  rc = stat4ValueFromExpr(pParse, pExpr, affinity, &alloc, &pVal);


















  assert( pVal==0 || pVal->db==pParse->db );





  *pbOk = (pVal!=0);
  return rc;
}

/*
** Attempt to extract a value from expression pExpr using the methods
** as described for sqlite3Stat4ProbeSetValue() above. 
**
** If successful, set *ppVal to point to a new value object and return 
** SQLITE_OK. If no value can be extracted, but no other error occurs
** (e.g. OOM), return SQLITE_OK and set *ppVal to NULL. Or, if an error
** does occur, return an SQLite error code. The final value of *ppVal
** is undefined in this case.
*/
int sqlite3Stat4ValueFromExpr(
  Parse *pParse,                  /* Parse context */
  Expr *pExpr,                    /* The expression to extract a value from */
  u8 affinity,                    /* Affinity to use */
  sqlite3_value **ppVal           /* OUT: New value object (or NULL) */
){
  return stat4ValueFromExpr(pParse, pExpr, affinity, 0, ppVal);
}

int sqlite3Stat4Column(
  sqlite3 *db,                    /* Database handle */
  const void *pRec,               /* Pointer to buffer containing record */
  int nRec,                       /* Size of buffer pRec in bytes */
  int iCol,                       /* Column to extract */
  sqlite3_value **ppVal           /* OUT: Extracted value */
){
  int rc = SQLITE_OK;
  Mem *pMem = *ppVal;
  if( pMem==0 ){
    pMem = (Mem*)sqlite3ValueNew(db);
    if( pMem==0 ){
      rc = SQLITE_NOMEM;
    }
  }

  if( rc==SQLITE_OK ){
    u32 t;
    int nHdr;
    int iHdr;
    int iField;
    int i;
    u8 *a = (u8*)pRec;

    iHdr = getVarint32(a, nHdr);
    iField = nHdr;
    for(i=0; i<iCol; i++){
      iHdr = getVarint32(&a[iHdr], t);
      iField += sqlite3VdbeSerialTypeLen(t);
    }

    iHdr = getVarint32(&a[iHdr], t);
    sqlite3VdbeSerialGet(&a[iField], t, pMem);
  }

  *ppVal = pMem;
  return rc;
}

/*
** Unless it is NULL, the argument must be an UnpackedRecord object returned
** by an earlier call to sqlite3Stat4ProbeSetValue(). This call deletes
** the object.

** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
*/
#include "sqliteInt.h"
#include "whereInt.h"
#include "vdbeInt.h"

/*
** Return the estimated number of output rows from a WHERE clause
*/
u64 sqlite3WhereOutputRowCount(WhereInfo *pWInfo){
  return sqlite3LogEstToInt(pWInfo->nRowOut);
}

      nRet += pTerm->truthProb;
    }else if( (pTerm->wtFlags & TERM_VNULL)==0 ){
      nRet -= 20;        assert( 20==sqlite3LogEst(4) );
    }
  }
  return nRet;
}

/* 
** This function is called to estimate the number of rows visited by a
** range-scan on a skip-scan index. For example:
**
**   CREATE INDEX i1 ON t1(a, b, c);
**   SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?;
**
** Value pLoop->nOut is currently set to the estimated number of rows 
** visited for scanning (a=? AND b=?). This function reduces that estimate 
** by some factor to account for the (c BETWEEN ? AND ?) expression based
** on the stat4 data for the index. this scan will be peformed multiple 
** times (once for each (a,b) combination that matches a=?) is dealt with 
** by the caller.
**
** It does this by scanning through all stat4 samples, comparing values
** extracted from pLower and pUpper with the corresponding column in each
** sample. If L and U are the number of samples found to be less than or
** equal to the values extracted from pLower and pUpper respectively, and
** N is the total number of samples, the pLoop->nOut value is adjusted
** as follows:
**
**   nOut = nOut * ( min(U - L, 1) / N )
**
** If pLower is NULL, or a value cannot be extracted from the term, L is
** set to zero. If pUpper is NULL, or a value cannot be extracted from it,
** U is set to N.
**
** Normally, this function sets *pbDone to 1 before returning. However,
** if no value can be extracted from either pLower or pUpper (and so the
** estimate of the number of rows delivered remains unchanged), *pbDone
** is left as is.
**
** If an error occurs, an SQLite error code is returned. Otherwise, 
** SQLITE_OK.
*/
static int whereRangeSkipScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
  WhereLoop *pLoop,    /* Update the .nOut value of this loop */
  int *pbDone          /* Set to true if at least one expr. value extracted */
){
  Index *p = pLoop->u.btree.pIndex;
  int nEq = pLoop->u.btree.nEq;
  sqlite3 *db = pParse->db;
  int nLower = 0;
  int nUpper = 0;
  int rc = SQLITE_OK;
  u8 aff = p->pTable->aCol[ p->aiColumn[nEq] ].affinity;
  CollSeq *pColl;
  
  sqlite3_value *p1 = 0;          /* Value extracted from pLower */
  sqlite3_value *p2 = 0;          /* Value extracted from pUpper */
  sqlite3_value *pVal = 0;        /* Value extracted from record */

  pColl = sqlite3LocateCollSeq(pParse, p->azColl[nEq]);
  if( pLower ){
    rc = sqlite3Stat4ValueFromExpr(pParse, pLower->pExpr->pRight, aff, &p1);
  }
  if( pUpper && rc==SQLITE_OK ){
    rc = sqlite3Stat4ValueFromExpr(pParse, pUpper->pExpr->pRight, aff, &p2);
  }

  if( p1 || p2 ){
    int i;
    int nDiff;
    for(i=0; rc==SQLITE_OK && i<p->nSample; i++){
      rc = sqlite3Stat4Column(db, p->aSample[i].p, p->aSample[i].n, nEq, &pVal);
      if( rc==SQLITE_OK && p1 ){
        int res = sqlite3MemCompare(p1, pVal, pColl);
        if( res<=0 ) nLower++;
      }
      if( rc==SQLITE_OK && p2 ){
        int res = sqlite3MemCompare(p2, pVal, pColl);
        if( res<=0 ) nUpper++;
      }
    }
    if( p2==0 ) nUpper = p->nSample;
    nDiff = (nUpper - nLower);
    if( nDiff<=0 ) nDiff = 1;
    pLoop->nOut -= (sqlite3LogEst(p->nSample) - sqlite3LogEst(nDiff));
    *pbDone = 1;
  }else{
    assert( *pbDone==0 );
  }

  sqlite3ValueFree(p1);
  sqlite3ValueFree(p2);
  sqlite3ValueFree(pVal);

  return rc;
}

/*
** This function is used to estimate the number of rows that will be visited
** by scanning an index for a range of values. The range may have an upper
** bound, a lower bound, or both. The WHERE clause terms that set the upper
** and lower bounds are represented by pLower and pUpper respectively. For
** example, assuming that index p is on t1(a):

  LogEst nNew;

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  Index *p = pLoop->u.btree.pIndex;
  int nEq = pLoop->u.btree.nEq;

  if( p->nSample>0

   && nEq<p->nSampleCol
   && OptimizationEnabled(pParse->db, SQLITE_Stat3) 
  ){
    if( nEq==pBuilder->nRecValid ){
      UnpackedRecord *pRec = pBuilder->pRec;
      tRowcnt a[2];
      u8 aff;

      /* Variable iLower will be set to the estimate of the number of rows in 
      ** the index that are less than the lower bound of the range query. The
      ** lower bound being the concatenation of $P and $L, where $P is the
      ** key-prefix formed by the nEq values matched against the nEq left-most
      ** columns of the index, and $L is the value in pLower.
      **
      ** Or, if pLower is NULL or $L cannot be extracted from it (because it
      ** is not a simple variable or literal value), the lower bound of the
      ** range is $P. Due to a quirk in the way whereKeyStats() works, even
      ** if $L is available, whereKeyStats() is called for both ($P) and 
      ** ($P:$L) and the larger of the two returned values used.
      **
      ** Similarly, iUpper is to be set to the estimate of the number of rows
      ** less than the upper bound of the range query. Where the upper bound
      ** is either ($P) or ($P:$U). Again, even if $U is available, both values
      ** of iUpper are requested of whereKeyStats() and the smaller used.
      */
      tRowcnt iLower;
      tRowcnt iUpper;

      if( nEq==p->nKeyCol ){
        aff = SQLITE_AFF_INTEGER;
      }else{
        aff = p->pTable->aCol[p->aiColumn[nEq]].affinity;
      }
      /* Determine iLower and iUpper using ($P) only. */
      if( nEq==0 ){
        iLower = 0;
        iUpper = sqlite3LogEstToInt(p->aiRowLogEst[0]);
      }else{
        /* Note: this call could be optimized away - since the same values must 
        ** have been requested when testing key $P in whereEqualScanEst().  */
        whereKeyStats(pParse, p, pRec, 0, a);
        iLower = a[0];
        iUpper = a[0] + a[1];
      }

      /* If possible, improve on the iLower estimate using ($P:$L). */
      if( pLower ){
        int bOk;                    /* True if value is extracted from pExpr */
        Expr *pExpr = pLower->pExpr->pRight;
        assert( (pLower->eOperator & (WO_GT|WO_GE))!=0 );
        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
        if( rc==SQLITE_OK && bOk ){
          tRowcnt iNew;
          whereKeyStats(pParse, p, pRec, 0, a);
          iNew = a[0] + ((pLower->eOperator & WO_GT) ? a[1] : 0);
          if( iNew>iLower ) iLower = iNew;
          nOut--;
        }
      }

      /* If possible, improve on the iUpper estimate using ($P:$U). */
      if( pUpper ){
        int bOk;                    /* True if value is extracted from pExpr */
        Expr *pExpr = pUpper->pExpr->pRight;
        assert( (pUpper->eOperator & (WO_LT|WO_LE))!=0 );
        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
        if( rc==SQLITE_OK && bOk ){
          tRowcnt iNew;
          whereKeyStats(pParse, p, pRec, 1, a);
          iNew = a[0] + ((pUpper->eOperator & WO_LE) ? a[1] : 0);
          if( iNew<iUpper ) iUpper = iNew;
          nOut--;
        }
      }

      pBuilder->pRec = pRec;
      if( rc==SQLITE_OK ){
        if( iUpper>iLower ){
          nNew = sqlite3LogEst(iUpper - iLower);
        }else{
          nNew = 10;        assert( 10==sqlite3LogEst(2) );
        }
        if( nNew<nOut ){
          nOut = nNew;
        }
        pLoop->nOut = (LogEst)nOut;
        WHERETRACE(0x10, ("range scan regions: %u..%u  est=%d\n",
                           (u32)iLower, (u32)iUpper, nOut));
        return SQLITE_OK;
      }
    }else{
      int bDone = 0;
      rc = whereRangeSkipScanEst(pParse, pLower, pUpper, pLoop, &bDone);
      if( bDone ) return rc;
    }
  }
#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(pBuilder);
#endif
  assert( pLower || pUpper );