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Comment:Improvements to the query optimizer. This is a work in progress. (CVS 2169)
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SHA1: 9b86993ff721b577b920c7c67fb41d3d4355fe88
User & Date: drh 2004-12-18 18:40:27.000
Context
2004-12-19
00:11
The optimizer now uses only the index and ignores the table if it can get away with doing so, thus saving a single BTree search per row of result. This could potentially double the speed of certain queries. The code passes all regression tests but new tests to exercise the new functionality are yet to be added. (CVS 2170) (check-in: e5aa489453 user: drh tags: trunk)
2004-12-18
18:40
Improvements to the query optimizer. This is a work in progress. (CVS 2169) (check-in: 9b86993ff7 user: drh tags: trunk)
2004-12-17
20:48
Fix a C++-ism in the previous change to tclsqlite.c. (CVS 2168) (check-in: b49b8fdd11 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/expr.c.
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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.175 2004/12/07 15:41:49 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**







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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.176 2004/12/18 18:40:27 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**
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){
  char *zDb = 0;       /* Name of the database.  The "X" in X.Y.Z */
  char *zTab = 0;      /* Name of the table.  The "Y" in X.Y.Z or Y.Z */
  char *zCol = 0;      /* Name of the column.  The "Z" */
  int i, j;            /* Loop counters */
  int cnt = 0;         /* Number of matching column names */
  int cntTab = 0;      /* Number of matching table names */
  sqlite3 *db = pParse->db;  /* The database */



  assert( pColumnToken && pColumnToken->z ); /* The Z in X.Y.Z cannot be NULL */
  zDb = sqlite3NameFromToken(pDbToken);
  zTab = sqlite3NameFromToken(pTableToken);
  zCol = sqlite3NameFromToken(pColumnToken);
  if( sqlite3_malloc_failed ){
    return 1;  /* Leak memory (zDb and zTab) if malloc fails */
  }
  assert( zTab==0 || pEList==0 );

  pExpr->iTable = -1;
  for(i=0; i<pSrcList->nSrc; i++){
    struct SrcList_item *pItem = &pSrcList->a[i];
    Table *pTab = pItem->pTab;
    Column *pCol;

    if( pTab==0 ) continue;
    assert( pTab->nCol>0 );
    if( zTab ){
      if( pItem->zAlias ){
        char *zTabName = pItem->zAlias;
        if( sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
      }else{
        char *zTabName = pTab->zName;
        if( zTabName==0 || sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
        if( zDb!=0 && sqlite3StrICmp(db->aDb[pTab->iDb].zName, zDb)!=0 ){
          continue;
        }
      }
    }
    if( 0==(cntTab++) ){
      pExpr->iTable = pItem->iCursor;
      pExpr->iDb = pTab->iDb;

    }
    for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
      if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
        cnt++;
        pExpr->iTable = pItem->iCursor;

        pExpr->iDb = pTab->iDb;
        /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
        pExpr->iColumn = j==pTab->iPKey ? -1 : j;
        pExpr->affinity = pTab->aCol[j].affinity;
        pExpr->pColl = pTab->aCol[j].pColl;
        break;
      }







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){
  char *zDb = 0;       /* Name of the database.  The "X" in X.Y.Z */
  char *zTab = 0;      /* Name of the table.  The "Y" in X.Y.Z or Y.Z */
  char *zCol = 0;      /* Name of the column.  The "Z" */
  int i, j;            /* Loop counters */
  int cnt = 0;         /* Number of matching column names */
  int cntTab = 0;      /* Number of matching table names */
  sqlite3 *db = pParse->db;         /* The database */
  struct SrcList_item *pItem;       /* Use for looping over pSrcList items */
  struct SrcList_item *pMatch = 0;  /* The matching pSrcList item */

  assert( pColumnToken && pColumnToken->z ); /* The Z in X.Y.Z cannot be NULL */
  zDb = sqlite3NameFromToken(pDbToken);
  zTab = sqlite3NameFromToken(pTableToken);
  zCol = sqlite3NameFromToken(pColumnToken);
  if( sqlite3_malloc_failed ){
    return 1;  /* Leak memory (zDb and zTab) if malloc fails */
  }
  assert( zTab==0 || pEList==0 );

  pExpr->iTable = -1;
  for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){

    Table *pTab = pItem->pTab;
    Column *pCol;

    if( pTab==0 ) continue;
    assert( pTab->nCol>0 );
    if( zTab ){
      if( pItem->zAlias ){
        char *zTabName = pItem->zAlias;
        if( sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
      }else{
        char *zTabName = pTab->zName;
        if( zTabName==0 || sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
        if( zDb!=0 && sqlite3StrICmp(db->aDb[pTab->iDb].zName, zDb)!=0 ){
          continue;
        }
      }
    }
    if( 0==(cntTab++) ){
      pExpr->iTable = pItem->iCursor;
      pExpr->iDb = pTab->iDb;
      pMatch = pItem;
    }
    for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
      if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
        cnt++;
        pExpr->iTable = pItem->iCursor;
        pMatch = pItem;
        pExpr->iDb = pTab->iDb;
        /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
        pExpr->iColumn = j==pTab->iPKey ? -1 : j;
        pExpr->affinity = pTab->aCol[j].affinity;
        pExpr->pColl = pTab->aCol[j].pColl;
        break;
      }
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      sqlite3SetString(&z, zTab, ".", zCol, 0);
    }else{
      z = sqliteStrDup(zCol);
    }
    sqlite3ErrorMsg(pParse, zErr, z);
    sqliteFree(z);
  }
















  /* Clean up and return
  */
  sqliteFree(zDb);
  sqliteFree(zTab);
  sqliteFree(zCol);
  sqlite3ExprDelete(pExpr->pLeft);







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      sqlite3SetString(&z, zTab, ".", zCol, 0);
    }else{
      z = sqliteStrDup(zCol);
    }
    sqlite3ErrorMsg(pParse, zErr, z);
    sqliteFree(z);
  }

  /* If a column from a table in pSrcList is referenced, then record
  ** this fact in the pSrcList.a[].colUsed bitmask.  Column 0 causes
  ** bit 0 to be set.  Column 1 sets bit 1.  And so forth.  If the
  ** column number is greater than the number of bits in the bitmask
  ** then set the high-order bit of the bitmask.
  */
  if( pExpr->iColumn>=0 && pMatch!=0 ){
    int n = pExpr->iColumn;
    if( n>=sizeof(Bitmask)*8 ){
      n = sizeof(Bitmask)*8-1;
    }
    assert( pMatch->iCursor==pExpr->iTable );
    pMatch->colUsed |= 1<<n;
  }

  /* Clean up and return
  */
  sqliteFree(zDb);
  sqliteFree(zTab);
  sqliteFree(zCol);
  sqlite3ExprDelete(pExpr->pLeft);
Changes to src/sqliteInt.h.
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/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.346 2004/12/07 15:41:49 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks













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/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.347 2004/12/18 18:40:27 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
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  int nAlloc;      /* Number of entries allocated for a[] below */
  struct IdList_item {
    char *zName;      /* Name of the identifier */
    int idx;          /* Index in some Table.aCol[] of a column named zName */
  } *a;
};






/*
** The following structure describes the FROM clause of a SELECT statement.
** Each table or subquery in the FROM clause is a separate element of
** the SrcList.a[] array.
**
** With the addition of multiple database support, the following structure
** can also be used to describe a particular table such as the table that







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  int nAlloc;      /* Number of entries allocated for a[] below */
  struct IdList_item {
    char *zName;      /* Name of the identifier */
    int idx;          /* Index in some Table.aCol[] of a column named zName */
  } *a;
};

/*
** The bitmask datatype defined below is used for various optimizations.
*/
typedef unsigned int Bitmask;

/*
** The following structure describes the FROM clause of a SELECT statement.
** Each table or subquery in the FROM clause is a separate element of
** the SrcList.a[] array.
**
** With the addition of multiple database support, the following structure
** can also be used to describe a particular table such as the table that
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    char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
    Table *pTab;      /* An SQL table corresponding to zName */
    Select *pSelect;  /* A SELECT statement used in place of a table name */
    int jointype;     /* Type of join between this table and the next */
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */

  } a[1];             /* One entry for each identifier on the list */
};

/*
** Permitted values of the SrcList.a.jointype field
*/
#define JT_INNER     0x0001    /* Any kind of inner or cross join */







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    char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
    Table *pTab;      /* An SQL table corresponding to zName */
    Select *pSelect;  /* A SELECT statement used in place of a table name */
    int jointype;     /* Type of join between this table and the next */
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */
    Bitmask colUsed;  /* Bit N (1<<N) set if column N or pTab is used */
  } a[1];             /* One entry for each identifier on the list */
};

/*
** Permitted values of the SrcList.a.jointype field
*/
#define JT_INNER     0x0001    /* Any kind of inner or cross join */
Changes to src/where.c.
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/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.




**
** $Id: where.c,v 1.121 2004/12/14 03:34:34 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.





































*/
typedef struct ExprInfo ExprInfo;
struct ExprInfo {
  Expr *p;                /* Pointer to the subexpression */
  u8 indexable;           /* True if this subexprssion is usable by an index */
  short int idxLeft;      /* p->pLeft is a column in this table number. -1 if
                          ** p->pLeft is not the column of any table */
  short int idxRight;     /* p->pRight is a column in this table number. -1 if
                          ** p->pRight is not the column of any table */
  unsigned prereqLeft;    /* Bitmask of tables referenced by p->pLeft */
  unsigned prereqRight;   /* Bitmask of tables referenced by p->pRight */
  unsigned prereqAll;     /* Bitmask of tables referenced by p */
};

/*
** An instance of the following structure keeps track of a mapping
** between VDBE cursor numbers and bitmasks.  The VDBE cursor numbers

** are small integers contained in SrcList_item.iCursor and Expr.iTable
** fields.  For any given WHERE clause, we want to track which cursors
** are being used, so we assign a single bit in a 32-bit word to track










** that cursor.  Then a 32-bit integer is able to show the set of all







** cursors being used.
*/
typedef struct ExprMaskSet ExprMaskSet;
struct ExprMaskSet {
  int n;          /* Number of assigned cursor values */
  int ix[31];     /* Cursor assigned to each bit */
};

/*
** Determine the number of elements in an array.
*/
#define ARRAYSIZE(X)  (sizeof(X)/sizeof(X[0]))

/*
** This routine is used to divide the WHERE expression into subexpressions
** separated by the AND operator.

**







** aSlot[] is an array of subexpressions structures.
** There are nSlot spaces left in this array.  This routine attempts to
** split pExpr into subexpressions and fills aSlot[] with those subexpressions.
** The return value is the number of slots filled.
*/
static int exprSplit(int nSlot, ExprInfo *aSlot, Expr *pExpr){
  int cnt = 0;
  if( pExpr==0 || nSlot<1 ) return 0;
  if( nSlot==1 || pExpr->op!=TK_AND ){
    aSlot[0].p = pExpr;
    return 1;












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/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is reponsible for
** 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".
**
** $Id: where.c,v 1.122 2004/12/18 18:40:27 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.
**
** The idxLeft and idxRight fields are the VDBE cursor numbers for the
** table that contains the column that appears on the left-hand and
** right-hand side of ExprInfo.p.  If either side of ExprInfo.p is
** something other than a simple column reference, then idxLeft or
** idxRight are -1.  
**
** It is the VDBE cursor number is the value stored in Expr.iTable
** when Expr.op==TK_COLUMN and the value stored in SrcList.a[].iCursor.
**
** prereqLeft, prereqRight, and prereqAll record sets of cursor numbers,
** but they do so indirectly.  A single ExprMaskSet structure translates
** cursor number into bits and the translated bit is stored in the prereq
** fields.  The translation is used in order to maximize the number of
** bits that will fit in a Bitmask.  The VDBE cursor numbers might be
** spread out over the non-negative integers.  For example, the cursor
** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45.  The ExprMaskSet
** translates these sparse cursor numbers into consecutive integers
** beginning with 0 in order to make the best possible use of the available
** bits in the Bitmask.  So, in the example above, the cursor numbers
** would be mapped into integers 0 through 7.
**
** prereqLeft tells us every VDBE cursor that is referenced on the
** left-hand side of ExprInfo.p.  prereqRight does the same for the
** right-hand side of the expression.  The following identity always
** holds:
**
**       prereqAll = prereqLeft | prereqRight
**
** The ExprInfo.indexable field is true if the ExprInfo.p expression
** is of a form that might control an index.  Indexable expressions
** look like this:
**
**              <column> <op> <expr>
**
** Where <column> is a simple column name and <op> is on of the operators
** that allowedOp() recognizes.  
*/
typedef struct ExprInfo ExprInfo;
struct ExprInfo {
  Expr *p;                /* Pointer to the subexpression */
  u8 indexable;           /* True if this subexprssion is usable by an index */
  short int idxLeft;      /* p->pLeft is a column in this table number. -1 if
                          ** p->pLeft is not the column of any table */
  short int idxRight;     /* p->pRight is a column in this table number. -1 if
                          ** p->pRight is not the column of any table */
  Bitmask prereqLeft;     /* Bitmask of tables referenced by p->pLeft */
  Bitmask prereqRight;    /* Bitmask of tables referenced by p->pRight */
  Bitmask prereqAll;      /* Bitmask of tables referenced by p */
};

/*
** An instance of the following structure keeps track of a mapping
** between VDBE cursor numbers and bits of the bitmasks in ExprInfo.
**
** The VDBE cursor numbers are small integers contained in 
** SrcList_item.iCursor and Expr.iTable fields.  For any given WHERE 

** clause, the cursor numbers might not begin with 0 and they might
** contain gaps in the numbering sequence.  But we want to make maximum
** use of the bits in our bitmasks.  This structure provides a mapping
** from the sparse cursor numbers into consecutive integers beginning
** with 0.
**
** If ExprMaskSet.ix[A]==B it means that The A-th bit of a Bitmask
** corresponds VDBE cursor number B.  The A-th bit of a bitmask is 1<<A.
**
** For example, if the WHERE clause expression used these VDBE
** cursors:  4, 5, 8, 29, 57, 73.  Then the  ExprMaskSet structure
** would map those cursor numbers into bits 0 through 5.
**
** Note that the mapping is not necessarily ordered.  In the example
** above, the mapping might go like this:  4->3, 5->1, 8->2, 29->0,
** 57->5, 73->4.  Or one of 719 other combinations might be used. It
** does not really matter.  What is important is that sparse cursor
** numbers all get mapped into bit numbers that begin with 0 and contain
** no gaps.
*/
typedef struct ExprMaskSet ExprMaskSet;
struct ExprMaskSet {
  int n;                          /* Number of assigned cursor values */
  int ix[sizeof(Bitmask)*8-1];    /* Cursor assigned to each bit */
};

/*
** Determine the number of elements in an array.
*/
#define ARRAYSIZE(X)  (sizeof(X)/sizeof(X[0]))

/*
** This routine identifies subexpressions in the WHERE clause where
** each subexpression is separate by the AND operator.  aSlot is 
** filled with pointers to the subexpressions.  For example:
**
**    WHERE  a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
**           \________/     \_______________/     \________________/
**            slot[0]            slot[1]               slot[2]
**
** The original WHERE clause in pExpr is unaltered.  All this routine
** does is make aSlot[] entries point to substructure within pExpr.
**
** aSlot[] is an array of subexpressions structures.  There are nSlot
** spaces left in this array.  This routine finds as many AND-separated
** subexpressions as it can and puts pointers to those subexpressions
** into aSlot[] entries.  The return value is the number of slots filled.
*/
static int exprSplit(int nSlot, ExprInfo *aSlot, Expr *pExpr){
  int cnt = 0;
  if( pExpr==0 || nSlot<1 ) return 0;
  if( nSlot==1 || pExpr->op!=TK_AND ){
    aSlot[0].p = pExpr;
    return 1;
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/*
** Initialize an expression mask set
*/
#define initMaskSet(P)  memset(P, 0, sizeof(*P))

/*
** Return the bitmask for the given cursor.  Assign a new bitmask
** if this is the first time the cursor has been seen.
*/
static int getMask(ExprMaskSet *pMaskSet, int iCursor){
  int i;
  for(i=0; i<pMaskSet->n; i++){
    if( pMaskSet->ix[i]==iCursor ) return 1<<i;


  }
  if( i==pMaskSet->n && i<ARRAYSIZE(pMaskSet->ix) ){
    pMaskSet->n++;
    pMaskSet->ix[i] = iCursor;
    return 1<<i;
  }
  return 0;
}

/*
** Destroy an expression mask set
*/







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/*
** Initialize an expression mask set
*/
#define initMaskSet(P)  memset(P, 0, sizeof(*P))

/*
** Return the bitmask for the given cursor number.  Assign a new bitmask
** if this is the first time the cursor has been seen.
*/
static Bitmask getMask(ExprMaskSet *pMaskSet, int iCursor){
  int i;
  for(i=0; i<pMaskSet->n; i++){
    if( pMaskSet->ix[i]==iCursor ){
      return ((Bitmask)1)<<i;
    }
  }
  if( i==pMaskSet->n && i<ARRAYSIZE(pMaskSet->ix) ){
    pMaskSet->n++;
    pMaskSet->ix[i] = iCursor;
    return ((Bitmask)1)<<i;
  }
  return 0;
}

/*
** Destroy an expression mask set
*/
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** In order for this routine to work, the calling function must have
** previously invoked sqlite3ExprResolveIds() on the expression.  See
** the header comment on that routine for additional information.
** The sqlite3ExprResolveIds() routines looks for column names and
** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
** the VDBE cursor number of the table.
*/
static int exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
  unsigned int mask = 0;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    mask = getMask(pMaskSet, p->iTable);
    if( mask==0 ) mask = -1;
    return mask;
  }
  if( p->pRight ){







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** In order for this routine to work, the calling function must have
** previously invoked sqlite3ExprResolveIds() on the expression.  See
** the header comment on that routine for additional information.
** The sqlite3ExprResolveIds() routines looks for column names and
** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
** the VDBE cursor number of the table.
*/
static Bitmask exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
  Bitmask mask = 0;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    mask = getMask(pMaskSet, p->iTable);
    if( mask==0 ) mask = -1;
    return mask;
  }
  if( p->pRight ){
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    }
  }
  return mask;
}

/*
** Return TRUE if the given operator is one of the operators that is
** allowed for an indexable WHERE clause.  The allowed operators are
** "=", "<", ">", "<=", ">=", and "IN".
*/
static int allowedOp(int op){
  assert( TK_GT==TK_LE-1 && TK_LE==TK_LT-1 && TK_LT==TK_GE-1 && TK_EQ==TK_GT-1);
  return op==TK_IN || (op>=TK_EQ && op<=TK_GE);
}

/*
** Swap two integers.
*/
#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}

/*
** Return the index in the SrcList that uses cursor iCur.  If iCur is
** used by the first entry in SrcList return 0.  If iCur is used by
** the second entry return 1.  And so forth.
**
** SrcList is the set of tables in the FROM clause in the order that
** they will be processed.  The value returned here gives us an index
** of which tables will be processed first.
*/
static int tableOrder(SrcList *pList, int iCur){
  int i;

  for(i=0; i<pList->nSrc; i++){
    if( pList->a[i].iCursor==iCur ) return i;
  }
  return -1;
}

/*
** The input to this routine is an ExprInfo structure with only the
** "p" field filled in.  The job of this routine is to analyze the







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    }
  }
  return mask;
}

/*
** Return TRUE if the given operator is one of the operators that is
** allowed for an indexable WHERE clause term.  The allowed operators are
** "=", "<", ">", "<=", ">=", and "IN".
*/
static int allowedOp(int op){
  assert( TK_GT==TK_LE-1 && TK_LE==TK_LT-1 && TK_LT==TK_GE-1 && TK_EQ==TK_GT-1);
  return op==TK_IN || (op>=TK_EQ && op<=TK_GE);
}

/*
** Swap two objects of type T.
*/
#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}

/*
** Return the index in the SrcList that uses cursor iCur.  If iCur is
** used by the first entry in SrcList return 0.  If iCur is used by
** the second entry return 1.  And so forth.
**
** SrcList is the set of tables in the FROM clause in the order that
** they will be processed.  The value returned here gives us an index
** of which tables will be processed first.
*/
static int tableOrder(SrcList *pList, int iCur){
  int i;
  struct SrcList_item *pItem;
  for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
    if( pItem->iCursor==iCur ) return i;
  }
  return -1;
}

/*
** The input to this routine is an ExprInfo structure with only the
** "p" field filled in.  The job of this routine is to analyze the
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      pMatch = pIdx;
      if( pIdx==pPreferredIdx ) break;
    }
  }
  *pbRev = sortOrder==SQLITE_SO_DESC;
  return pMatch;
}































































































/*
** Check table to see if the ORDER BY clause in pOrderBy can be satisfied
** by sorting in order of ROWID.  Return true if so and set *pbRev to be
** true for reverse ROWID and false for forward ROWID order.
*/
static int sortableByRowid(







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      pMatch = pIdx;
      if( pIdx==pPreferredIdx ) break;
    }
  }
  *pbRev = sortOrder==SQLITE_SO_DESC;
  return pMatch;
}

/*
** This routine decides if pIdx can be used to satisfy the ORDER BY
** clause.  If it can, it returns 1.  If pIdx cannot satisfy the
** ORDER BY clause, this routine returns 0.
**
** pOrderBy is an ORDER BY clause from a SELECT statement.  pTab is the
** left-most table in the FROM clause of that same SELECT statement and
** the table has a cursor number of "base".  pIdx is an index on pTab.
**
** nEqCol is the number of columns of pIdx that are used as equality
** constraints.  Any of these columns may be missing from the ORDER BY
** clause and the match can still be a success.
**
** If the index is UNIQUE, then the ORDER BY clause is allowed to have
** additional terms past the end of the index and the match will still
** be a success.
**
** All terms of the ORDER BY that match against the index must be either
** ASC or DESC.  (Terms of the ORDER BY clause past the end of a UNIQUE
** index do not need to satisfy this constraint.)  The *pbRev value is
** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if
** the ORDER BY clause is all ASC.
*/
static int isSortingIndex(
  Parse *pParse,          /* Parsing context */
  Index *pIdx,            /* The index we are testing */
  Table *pTab,            /* The table to be sorted */
  int base,               /* Cursor number for pTab */
  ExprList *pOrderBy,     /* The ORDER BY clause */
  int nEqCol,             /* Number of index columns with == constraints */
  int *pbRev              /* Set to 1 if ORDER BY is DESC */
){
  int i, j;                    /* Loop counters */
  int sortOrder;               /* Which direction we are sorting */
  int nTerm;                   /* Number of ORDER BY terms */
  struct ExprList_item *pTerm; /* A term of the ORDER BY clause */
  sqlite3 *db = pParse->db;

  assert( pOrderBy!=0 );
  nTerm = pOrderBy->nExpr;
  assert( nTerm>0 );

  /* Match terms of the ORDER BY clause against columns of
  ** the index.
  */
  for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<pIdx->nColumn; i++){
    Expr *pExpr;       /* The expression of the ORDER BY pTerm */
    CollSeq *pColl;    /* The collating sequence of pExpr */

    pExpr = pTerm->pExpr;
    if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){
      /* Can not use an index sort on anything that is not a column in the
      ** left-most table of the FROM clause */
      return 0;
    }
    pColl = sqlite3ExprCollSeq(pParse, pExpr);
    if( !pColl ) pColl = db->pDfltColl;
    if( pExpr->iColumn!=pIdx->aiColumn[i] && pColl!=pIdx->keyInfo.aColl[i] ){
      if( i<=nEqCol ){
        /* If an index column that is constrained by == fails to match an
        ** ORDER BY term, that is OK.  Just ignore that column of the index
        */
        continue;
      }else{
        /* If an index column fails to match and is not constrained by ==
        ** then the index cannot satisfy the ORDER BY constraint.
        */
        return 0;
      }
    }
    if( i>nEqCol ){
      if( pTerm->sortOrder!=sortOrder ){
        /* Indices can only be used if all ORDER BY terms past the
        ** equality constraints are all either DESC or ASC. */
        return 0;
      }
    }else{
      sortOrder = pTerm->sortOrder;
    }
    j++;
    pTerm++;
  }

  /* The index can be used for sorting if all terms of the ORDER BY clause
  ** or covered or if we ran out of index columns and the it is a UNIQUE
  ** index.
  */
  if( j>=nTerm || (i>=pIdx->nColumn && pIdx->onError!=OE_None) ){
    *pbRev = sortOrder==SQLITE_SO_DESC;
    return 1;
  }
  return 0;
}

/*
** Check table to see if the ORDER BY clause in pOrderBy can be satisfied
** by sorting in order of ROWID.  Return true if so and set *pbRev to be
** true for reverse ROWID and false for forward ROWID order.
*/
static int sortableByRowid(
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    pLevel->inP2 = sqlite3VdbeAddOp(v, OP_IdxColumn, iTab, 0);
    pLevel->inOp = OP_Next;
    pLevel->inP1 = iTab;
  }
  disableTerm(pLevel, &pTerm->p);
}







/*
** Generate the beginning of the loop used for WHERE clause processing.
** The return value is a pointer to an (opaque) structure that contains
** information needed to terminate the loop.  Later, the calling routine
** should invoke sqlite3WhereEnd() with the return value of this function
** in order to complete the WHERE clause processing.







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    pLevel->inP2 = sqlite3VdbeAddOp(v, OP_IdxColumn, iTab, 0);
    pLevel->inOp = OP_Next;
    pLevel->inP1 = iTab;
  }
  disableTerm(pLevel, &pTerm->p);
}

/*
** The number of bits in a Bitmask
*/
#define BMS  (sizeof(Bitmask)*8-1)


/*
** Generate the beginning of the loop used for WHERE clause processing.
** The return value is a pointer to an (opaque) structure that contains
** information needed to terminate the loop.  Later, the calling routine
** should invoke sqlite3WhereEnd() with the return value of this function
** in order to complete the WHERE clause processing.
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  Fetch *pFetch         /* Initial location of cursors.  NULL otherwise */
){
  int i;                     /* Loop counter */
  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
  int brk, cont = 0;         /* Addresses used during code generation */
  int nExpr;           /* Number of subexpressions in the WHERE clause */
  int loopMask;        /* One bit set for each outer loop */
  int haveKey = 0;     /* True if KEY is on the stack */
  ExprInfo *pTerm;     /* A single term in the WHERE clause; ptr to aExpr[] */
  ExprMaskSet maskSet; /* The expression mask set */
  int iDirectEq[32];   /* Term of the form ROWID==X for the N-th table */
  int iDirectLt[32];   /* Term of the form ROWID<X or ROWID<=X */
  int iDirectGt[32];   /* Term of the form ROWID>X or ROWID>=X */
  ExprInfo aExpr[101]; /* The WHERE clause is divided into these terms */

  /* pushKey is only allowed if there is a single table (as in an INSERT or
  ** UPDATE statement)
  */
  assert( pushKey==0 || pTabList->nSrc==1 );

  /*
  */

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.  If the aExpr[]
  ** array fills up, the last entry might point to an expression which
  ** contains additional unfactored AND operators.
  */
  initMaskSet(&maskSet);
  memset(aExpr, 0, sizeof(aExpr));







|



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697
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  Fetch *pFetch         /* Initial location of cursors.  NULL otherwise */
){
  int i;                     /* Loop counter */
  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
  int brk, cont = 0;         /* Addresses used during code generation */
  int nExpr;           /* Number of subexpressions in the WHERE clause */
  Bitmask loopMask;    /* One bit set for each outer loop */
  int haveKey = 0;     /* True if KEY is on the stack */
  ExprInfo *pTerm;     /* A single term in the WHERE clause; ptr to aExpr[] */
  ExprMaskSet maskSet; /* The expression mask set */
  int iDirectEq[BMS];  /* Term of the form ROWID==X for the N-th table */
  int iDirectLt[BMS];  /* Term of the form ROWID<X or ROWID<=X */
  int iDirectGt[BMS];  /* Term of the form ROWID>X or ROWID>=X */
  ExprInfo aExpr[101]; /* The WHERE clause is divided into these terms */

  /* pushKey is only allowed if there is a single table (as in an INSERT or
  ** UPDATE statement)
  */
  assert( pushKey==0 || pTabList->nSrc==1 );




  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.  If the aExpr[]
  ** array fills up, the last entry might point to an expression which
  ** contains additional unfactored AND operators.
  */
  initMaskSet(&maskSet);
  memset(aExpr, 0, sizeof(aExpr));
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    /* If we are executing a trigger body, remove all references to
    ** new.* and old.* tables from the prerequisite masks.
    */
    if( (pStack = pParse->trigStack)!=0 ){
      int x;
      if( (x=pStack->newIdx) >= 0 ){
        int mask = ~getMask(&maskSet, x);
        pTerm->prereqRight &= mask;
        pTerm->prereqLeft &= mask;
        pTerm->prereqAll &= mask;
      }
      if( (x=pStack->oldIdx) >= 0 ){
        int mask = ~getMask(&maskSet, x);
        pTerm->prereqRight &= mask;
        pTerm->prereqLeft &= mask;
        pTerm->prereqAll &= mask;
      }
    }
  }








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    /* If we are executing a trigger body, remove all references to
    ** new.* and old.* tables from the prerequisite masks.
    */
    if( (pStack = pParse->trigStack)!=0 ){
      int x;
      if( (x=pStack->newIdx) >= 0 ){
        Bitmask mask = ~getMask(&maskSet, x);
        pTerm->prereqRight &= mask;
        pTerm->prereqLeft &= mask;
        pTerm->prereqAll &= mask;
      }
      if( (x=pStack->oldIdx) >= 0 ){
        Bitmask mask = ~getMask(&maskSet, x);
        pTerm->prereqRight &= mask;
        pTerm->prereqLeft &= mask;
        pTerm->prereqAll &= mask;
      }
    }
  }

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  ** first 32 tables are candidates for indices.  This is (again) due
  ** to the limit of 32 bits in an integer bitmask.
  */
  loopMask = 0;
  for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++){
    int j;
    WhereLevel *pLevel = &pWInfo->a[i];
    int iCur = pTabList->a[i].iCursor;    /* The cursor for this table */
    int mask = getMask(&maskSet, iCur);   /* Cursor mask for this table */
    Table *pTab = pTabList->a[i].pTab;
    Index *pIdx;
    Index *pBestIdx = 0;
    int bestScore = 0;


    /* Check to see if there is an expression that uses only the
    ** ROWID field of this table.  For terms of the form ROWID==expr
    ** set iDirectEq[i] to the index of the term.  For terms of the
    ** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index.
    ** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i].
    **







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  ** first 32 tables are candidates for indices.  This is (again) due
  ** to the limit of 32 bits in an integer bitmask.
  */
  loopMask = 0;
  for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++){
    int j;
    WhereLevel *pLevel = &pWInfo->a[i];
    int iCur = pTabList->a[i].iCursor;       /* The cursor for this table */
    Bitmask mask = getMask(&maskSet, iCur);  /* Cursor mask for this table */
    Table *pTab = pTabList->a[i].pTab;
    Index *pIdx;
    Index *pBestIdx = 0;
    int bestScore = 0;
    int bestRev = 0;

    /* Check to see if there is an expression that uses only the
    ** ROWID field of this table.  For terms of the form ROWID==expr
    ** set iDirectEq[i] to the index of the term.  For terms of the
    ** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index.
    ** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i].
    **
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    /* Do a search for usable indices.  Leave pBestIdx pointing to
    ** the "best" index.  pBestIdx is left set to NULL if no indices
    ** are usable.
    **
    ** The best index is determined as follows.  For each of the
    ** left-most terms that is fixed by an equality operator, add
    ** 8 to the score.  The right-most term of the index may be
    ** constrained by an inequality.  Add 1 if for an "x<..." constraint
    ** and add 2 for an "x>..." constraint.  Chose the index that








    ** gives the best score.
    **
    ** This scoring system is designed so that the score can later be
    ** used to determine how the index is used.  If the score&7 is 0
    ** then all constraints are equalities.  If score&1 is not 0 then
    ** there is an inequality used as a termination key.  (ex: "x<...")
    ** If score&2 is not 0 then there is an inequality used as the
    ** start key.  (ex: "x>...").  A score or 4 is the special case
    ** of an IN operator constraint.  (ex:  "x IN ...").
    **
    ** The IN operator (as in "<expr> IN (...)") is treated the same as
    ** an equality comparison except that it can only be used on the
    ** left-most column of an index and other terms of the WHERE clause
    ** cannot be used in conjunction with the IN operator to help satisfy
    ** other columns of the index.
    */
    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
      int eqMask = 0;  /* Index columns covered by an x=... term */
      int ltMask = 0;  /* Index columns covered by an x<... term */
      int gtMask = 0;  /* Index columns covered by an x>... term */
      int inMask = 0;  /* Index columns covered by an x IN .. term */

      int nEq, m, score;


      if( pIdx->nColumn>32 ) continue;  /* Ignore indices too many columns */

      for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
        Expr *pX = pTerm->p;
        CollSeq *pColl = sqlite3ExprCollSeq(pParse, pX->pLeft);
        if( !pColl && pX->pRight ){
          pColl = sqlite3ExprCollSeq(pParse, pX->pRight);
        }
        if( !pColl ){







|
|
|
>
>
>
>
>
>
>
>
|


|
|

|
|









|
|
|
|
>
|

>
|
>







822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873

    /* Do a search for usable indices.  Leave pBestIdx pointing to
    ** the "best" index.  pBestIdx is left set to NULL if no indices
    ** are usable.
    **
    ** The best index is determined as follows.  For each of the
    ** left-most terms that is fixed by an equality operator, add
    ** 32 to the score.  The right-most term of the index may be
    ** constrained by an inequality.  Add 4 if for an "x<..." constraint
    ** and add 8 for an "x>..." constraint.  If both constraints
    ** are present, add 12.
    **
    ** If the left-most term of the index uses an IN operator
    ** (ex:  "x IN (...)")  then add 16 to the score.
    **
    ** If an index can be used for sorting, add 2 to the score.
    ** If an index contains all the terms of a table that are ever
    ** used by any expression in the SQL statement, then add 1 to
    ** the score.
    **
    ** This scoring system is designed so that the score can later be
    ** used to determine how the index is used.  If the score&0x1c is 0
    ** then all constraints are equalities.  If score&0x4 is not 0 then
    ** there is an inequality used as a termination key.  (ex: "x<...")
    ** If score&0x8 is not 0 then there is an inequality used as the
    ** start key.  (ex: "x>...").  A score or 0x10 is the special case
    ** of an IN operator constraint.  (ex:  "x IN ...").
    **
    ** The IN operator (as in "<expr> IN (...)") is treated the same as
    ** an equality comparison except that it can only be used on the
    ** left-most column of an index and other terms of the WHERE clause
    ** cannot be used in conjunction with the IN operator to help satisfy
    ** other columns of the index.
    */
    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
      Bitmask eqMask = 0;  /* Index columns covered by an x=... term */
      Bitmask ltMask = 0;  /* Index columns covered by an x<... term */
      Bitmask gtMask = 0;  /* Index columns covered by an x>... term */
      Bitmask inMask = 0;  /* Index columns covered by an x IN .. term */
      Bitmask m;
      int nEq, score, bRev = 0;

      if( pIdx->nColumn>sizeof(eqMask)*8 ){
        continue;  /* Ignore indices with too many columns to analyze */
      }
      for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
        Expr *pX = pTerm->p;
        CollSeq *pColl = sqlite3ExprCollSeq(pParse, pX->pLeft);
        if( !pColl && pX->pRight ){
          pColl = sqlite3ExprCollSeq(pParse, pX->pRight);
        }
        if( !pColl ){
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747



748
749
750
751
752













753
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755

756
757
758
759
760
761
762
763
764
765
766
767
            if( pIdx->aiColumn[k]==iColumn ){
              switch( pX->op ){
                case TK_IN: {
                  if( k==0 ) inMask |= 1;
                  break;
                }
                case TK_EQ: {
                  eqMask |= 1<<k;
                  break;
                }
                case TK_LE:
                case TK_LT: {
                  ltMask |= 1<<k;
                  break;
                }
                case TK_GE:
                case TK_GT: {
                  gtMask |= 1<<k;
                  break;
                }
                default: {
                  /* CANT_HAPPEN */
                  assert( 0 );
                  break;
                }
              }
              break;
            }
          }
        }
      }

      /* The following loop ends with nEq set to the number of columns
      ** on the left of the index with == constraints.
      */
      for(nEq=0; nEq<pIdx->nColumn; nEq++){
        m = (1<<(nEq+1))-1;
        if( (m & eqMask)!=m ) break;
      }



      score = nEq*8;   /* Base score is 8 times number of == constraints */
      m = 1<<nEq;
      if( m & ltMask ) score++;    /* Increase score for a < constraint */
      if( m & gtMask ) score+=2;   /* Increase score for a > constraint */
      if( score==0 && inMask ) score = 4;  /* Default score for IN constraint */













      if( score>bestScore ){
        pBestIdx = pIdx;
        bestScore = score;

      }
    }
    pLevel->pIdx = pBestIdx;
    pLevel->score = bestScore;
    pLevel->bRev = 0;
    loopMask |= mask;
    if( pBestIdx ){
      pLevel->iCur = pParse->nTab++;
    }
  }

  /* Check to see if the ORDER BY clause is or can be satisfied by the







|




|




|


















|


>
>
>
|
|
|
|
|
>
>
>
>
>
>
>
>
>
>
>
>
>



>




|







886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
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909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
            if( pIdx->aiColumn[k]==iColumn ){
              switch( pX->op ){
                case TK_IN: {
                  if( k==0 ) inMask |= 1;
                  break;
                }
                case TK_EQ: {
                  eqMask |= ((Bitmask)1)<<k;
                  break;
                }
                case TK_LE:
                case TK_LT: {
                  ltMask |= ((Bitmask)1)<<k;
                  break;
                }
                case TK_GE:
                case TK_GT: {
                  gtMask |= ((Bitmask)1)<<k;
                  break;
                }
                default: {
                  /* CANT_HAPPEN */
                  assert( 0 );
                  break;
                }
              }
              break;
            }
          }
        }
      }

      /* The following loop ends with nEq set to the number of columns
      ** on the left of the index with == constraints.
      */
      for(nEq=0; nEq<pIdx->nColumn; nEq++){
        m = (((Bitmask)1)<<(nEq+1))-1;
        if( (m & eqMask)!=m ) break;
      }

      /* Begin assemblying the score
      */
      score = nEq*32;   /* Base score is 32 times number of == constraints */
      m = ((Bitmask)1)<<nEq;
      if( m & ltMask ) score+=4;    /* Increase score for a < constraint */
      if( m & gtMask ) score+=8;    /* Increase score for a > constraint */
      if( score==0 && inMask ) score = 16; /* Default score for IN constraint */

      /* Give bonus points if this index can be used for sorting
      */
      if( i==0 && score>0 && ppOrderBy && *ppOrderBy ){
        int base = pTabList->a[0].iCursor;
        if( isSortingIndex(pParse, pIdx, pTab, base, *ppOrderBy, nEq, &bRev) ){
          score += 2;
        }
      }

      /* If the score for this index is the best we have seen so far, then
      ** save it
      */
      if( score>bestScore ){
        pBestIdx = pIdx;
        bestScore = score;
        bestRev = bRev;
      }
    }
    pLevel->pIdx = pBestIdx;
    pLevel->score = bestScore;
    pLevel->bRev = bestRev;
    loopMask |= mask;
    if( pBestIdx ){
      pLevel->iCur = pParse->nTab++;
    }
  }

  /* Check to see if the ORDER BY clause is or can be satisfied by the
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
     iCur = pTabList->a[0].iCursor;
     if( pIdx==0 && sortableByRowid(iCur, *ppOrderBy, &bRev) ){
       /* The ORDER BY clause specifies ROWID order, which is what we
       ** were going to be doing anyway...
       */
       *ppOrderBy = 0;
       pLevel0->bRev = bRev;
     }else if( pLevel0->score==4 ){
       /* If there is already an IN index on the left-most table,
       ** it will not give the correct sort order.
       ** So, pretend that no suitable index is found.
       */
     }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
       /* If the left-most column is accessed using its ROWID, then do
       ** not try to sort by index.  But do delete the ORDER BY clause
       ** if it is redundant.
       */
     }else{
       int nEqCol = (pLevel0->score+4)/8;
       pSortIdx = findSortingIndex(pParse, pTab, iCur, 
                                   *ppOrderBy, pIdx, nEqCol, &bRev);
     }
     if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){
       if( pIdx==0 ){
         pLevel0->pIdx = pSortIdx;
         pLevel0->iCur = pParse->nTab++;







|










|







974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
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991
992
993
994
995
996
997
998
999
     iCur = pTabList->a[0].iCursor;
     if( pIdx==0 && sortableByRowid(iCur, *ppOrderBy, &bRev) ){
       /* The ORDER BY clause specifies ROWID order, which is what we
       ** were going to be doing anyway...
       */
       *ppOrderBy = 0;
       pLevel0->bRev = bRev;
     }else if( pLevel0->score==16 ){
       /* If there is already an IN index on the left-most table,
       ** it will not give the correct sort order.
       ** So, pretend that no suitable index is found.
       */
     }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
       /* If the left-most column is accessed using its ROWID, then do
       ** not try to sort by index.  But do delete the ORDER BY clause
       ** if it is redundant.
       */
     }else{
       int nEqCol = (pLevel0->score+16)/32;
       pSortIdx = findSortingIndex(pParse, pTab, iCur, 
                                   *ppOrderBy, pIdx, nEqCol, &bRev);
     }
     if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){
       if( pIdx==0 ){
         pLevel0->pIdx = pSortIdx;
         pLevel0->iCur = pParse->nTab++;
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
      codeEqualityTerm(pParse, pTerm, brk, pLevel);
      cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk);
      haveKey = 0;
      sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk);
      pLevel->op = OP_Noop;
    }else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){
      /* Case 2:  There is an index and all terms of the WHERE clause that
      **          refer to the index using the "==" or "IN" operators.
      */
      int start;
      int nColumn = (pLevel->score+4)/8;
      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);

      /* For each column of the index, find the term of the WHERE clause that
      ** constraints that column.  If the WHERE clause term is X=expr, then
      ** evaluation expr and leave the result on the stack */
      for(j=0; j<nColumn; j++){
        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){







|




|







1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
      codeEqualityTerm(pParse, pTerm, brk, pLevel);
      cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk);
      haveKey = 0;
      sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk);
      pLevel->op = OP_Noop;
    }else if( pIdx!=0 && pLevel->score>0 && (pLevel->score&0x0c)==0 ){
      /* Case 2:  There is an index and all terms of the WHERE clause that
      **          refer to the index using the "==" or "IN" operators.
      */
      int start;
      int nColumn = (pLevel->score+16)/32;
      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);

      /* For each column of the index, find the term of the WHERE clause that
      ** constraints that column.  If the WHERE clause term is X=expr, then
      ** evaluation expr and leave the result on the stack */
      for(j=0; j<nColumn; j++){
        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
      **         use the "==" operator.
      **
      **         This case is also used when there are no WHERE clause
      **         constraints but an index is selected anyway, in order
      **         to force the output order to conform to an ORDER BY.
      */
      int score = pLevel->score;
      int nEqColumn = score/8;
      int start;
      int leFlag=0, geFlag=0;
      int testOp;

      /* Evaluate the equality constraints
      */
      for(j=0; j<nEqColumn; j++){







|







1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
      **         use the "==" operator.
      **
      **         This case is also used when there are no WHERE clause
      **         constraints but an index is selected anyway, in order
      **         to force the output order to conform to an ORDER BY.
      */
      int score = pLevel->score;
      int nEqColumn = score/32;
      int start;
      int leFlag=0, geFlag=0;
      int testOp;

      /* Evaluate the equality constraints
      */
      for(j=0; j<nEqColumn; j++){
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
      /* Generate the termination key.  This is the key value that
      ** will end the search.  There is no termination key if there
      ** are no equality terms and no "X<..." term.
      **
      ** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
      ** key computed here really ends up being the start key.
      */
      if( (score & 1)!=0 ){
        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
          Expr *pX = pTerm->p;
          if( pX==0 ) continue;
          if( pTerm->idxLeft==iCur
             && (pX->op==TK_LT || pX->op==TK_LE)
             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
             && pX->pLeft->iColumn==pIdx->aiColumn[j]
          ){
            sqlite3ExprCode(pParse, pX->pRight);
            leFlag = pX->op==TK_LE;
            disableTerm(pLevel, &pTerm->p);
            break;
          }
        }
        testOp = OP_IdxGE;
      }else{
        testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop;
        leFlag = 1;
      }
      if( testOp!=OP_Noop ){
        int nCol = nEqColumn + (score & 1);
        pLevel->iMem = pParse->nMem++;
        buildIndexProbe(v, nCol, brk, pIdx);
        if( pLevel->bRev ){
          int op = leFlag ? OP_MoveLe : OP_MoveLt;
          sqlite3VdbeAddOp(v, op, pLevel->iCur, brk);
        }else{
          sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);







|




















|







1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
      /* Generate the termination key.  This is the key value that
      ** will end the search.  There is no termination key if there
      ** are no equality terms and no "X<..." term.
      **
      ** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
      ** key computed here really ends up being the start key.
      */
      if( (score & 4)!=0 ){
        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
          Expr *pX = pTerm->p;
          if( pX==0 ) continue;
          if( pTerm->idxLeft==iCur
             && (pX->op==TK_LT || pX->op==TK_LE)
             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
             && pX->pLeft->iColumn==pIdx->aiColumn[j]
          ){
            sqlite3ExprCode(pParse, pX->pRight);
            leFlag = pX->op==TK_LE;
            disableTerm(pLevel, &pTerm->p);
            break;
          }
        }
        testOp = OP_IdxGE;
      }else{
        testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop;
        leFlag = 1;
      }
      if( testOp!=OP_Noop ){
        int nCol = nEqColumn + ((score & 4)!=0);
        pLevel->iMem = pParse->nMem++;
        buildIndexProbe(v, nCol, brk, pIdx);
        if( pLevel->bRev ){
          int op = leFlag ? OP_MoveLe : OP_MoveLt;
          sqlite3VdbeAddOp(v, op, pLevel->iCur, brk);
        }else{
          sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
      ** equality terms and if there is no "X>..." term.  In
      ** that case, generate a "Rewind" instruction in place of the
      ** start key search.
      **
      ** 2002-Dec-04: In the case of a reverse-order search, the so-called
      ** "start" key really ends up being used as the termination key.
      */
      if( (score & 2)!=0 ){
        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
          Expr *pX = pTerm->p;
          if( pX==0 ) continue;
          if( pTerm->idxLeft==iCur
             && (pX->op==TK_GT || pX->op==TK_GE)
             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
             && pX->pLeft->iColumn==pIdx->aiColumn[j]
          ){
            sqlite3ExprCode(pParse, pX->pRight);
            geFlag = pX->op==TK_GE;
            disableTerm(pLevel, &pTerm->p);
            break;
          }
        }
      }else{
        geFlag = 1;
      }
      if( nEqColumn>0 || (score&2)!=0 ){
        int nCol = nEqColumn + ((score&2)!=0);
        buildIndexProbe(v, nCol, brk, pIdx);
        if( pLevel->bRev ){
          pLevel->iMem = pParse->nMem++;
          sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
          testOp = OP_IdxLT;
        }else{
          int op = geFlag ? OP_MoveGe : OP_MoveGt;







|

















|
|







1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
      ** equality terms and if there is no "X>..." term.  In
      ** that case, generate a "Rewind" instruction in place of the
      ** start key search.
      **
      ** 2002-Dec-04: In the case of a reverse-order search, the so-called
      ** "start" key really ends up being used as the termination key.
      */
      if( (score & 8)!=0 ){
        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
          Expr *pX = pTerm->p;
          if( pX==0 ) continue;
          if( pTerm->idxLeft==iCur
             && (pX->op==TK_GT || pX->op==TK_GE)
             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
             && pX->pLeft->iColumn==pIdx->aiColumn[j]
          ){
            sqlite3ExprCode(pParse, pX->pRight);
            geFlag = pX->op==TK_GE;
            disableTerm(pLevel, &pTerm->p);
            break;
          }
        }
      }else{
        geFlag = 1;
      }
      if( nEqColumn>0 || (score&8)!=0 ){
        int nCol = nEqColumn + ((score&8)!=0);
        buildIndexProbe(v, nCol, brk, pIdx);
        if( pLevel->bRev ){
          pLevel->iMem = pParse->nMem++;
          sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
          testOp = OP_IdxLT;
        }else{
          int op = geFlag ? OP_MoveGe : OP_MoveGt;
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
        sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
        sqlite3VdbeAddOp(v, testOp, pLevel->iCur, brk);
        if( (leFlag && !pLevel->bRev) || (!geFlag && pLevel->bRev) ){
          sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC);
        }
      }
      sqlite3VdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
      sqlite3VdbeAddOp(v, OP_IdxIsNull, nEqColumn + (score & 1), cont);
      sqlite3VdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
      if( i==pTabList->nSrc-1 && pushKey ){
        haveKey = 1;
      }else{
        sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
        haveKey = 0;
      }







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        sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
        sqlite3VdbeAddOp(v, testOp, pLevel->iCur, brk);
        if( (leFlag && !pLevel->bRev) || (!geFlag && pLevel->bRev) ){
          sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC);
        }
      }
      sqlite3VdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
      sqlite3VdbeAddOp(v, OP_IdxIsNull, nEqColumn + ((score&4)!=0), cont);
      sqlite3VdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
      if( i==pTabList->nSrc-1 && pushKey ){
        haveKey = 1;
      }else{
        sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
        haveKey = 0;
      }
Changes to test/where.test.
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# 2001 September 15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the use of indices in WHERE clases.
#
# $Id: where.test,v 1.24 2004/11/22 19:12:21 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
do_test where-1.0 {













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# 2001 September 15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the use of indices in WHERE clases.
#
# $Id: where.test,v 1.25 2004/12/18 18:40:28 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
do_test where-1.0 {
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    SELECT * FROM t3 WHERE b>0 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 sort}
do_test where-6.8 {
  cksort {
    SELECT * FROM t3 WHERE a IN (3,5,7,1,9,4,2) ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 sort}
do_test where-6.9.1 {
  cksort {
    SELECT * FROM t3 WHERE a=1 AND c>0 ORDER BY a LIMIT 3
  }
} {1 100 4 nosort}
do_test where-6.9.2 {
  cksort {







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    SELECT * FROM t3 WHERE b>0 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 sort}
do_test where-6.8 {
  cksort {
    SELECT * FROM t3 WHERE a IN (3,5,7,1,9,4,2) ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 nosort}
do_test where-6.9.1 {
  cksort {
    SELECT * FROM t3 WHERE a=1 AND c>0 ORDER BY a LIMIT 3
  }
} {1 100 4 nosort}
do_test where-6.9.2 {
  cksort {