SQLite

** 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 1.156 2005/07/28 23:12:08 drh Exp $
*/
#include "sqliteInt.h"

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  (sizeof(Bitmask)*8)

  Expr *pExpr;            /* Pointer to the subexpression */
  u16 idx;                /* Index of this term in pWC->a[] */
  i16 iPartner;           /* Disable pWC->a[iPartner] when this term disabled */
  u16 flags;              /* Bit flags.  See below */
  i16 leftCursor;         /* Cursor number of X in "X <op> <expr>" */
  i16 leftColumn;         /* Column number of X in "X <op> <expr>" */
  u16 operator;           /* A WO_xx value describing <op> */
  u8 nPartner;            /* Number of partners that must disable us */
  WhereClause *pWC;       /* The clause this term is part of */
  Bitmask prereqRight;    /* Bitmask of tables used by pRight */
  Bitmask prereqAll;      /* Bitmask of tables referenced by p */
};

/*
** Allowed values of WhereTerm.flags

      WhereTerm *pNew;
      Expr *pDup;
      if( pTerm->leftCursor>=0 ){
        pDup = sqlite3ExprDup(pExpr);
        pNew = whereClauseInsert(pTerm->pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
        if( pNew==0 ) return;
        pNew->iPartner = pTerm->idx;
        pTerm->nPartner = 1;
      }else{
        pDup = pExpr;
        pNew = pTerm;
      }
      exprCommute(pDup);
      pLeft = pDup->pLeft;
      pNew->leftCursor = pLeft->iTable;
      pNew->leftColumn = pLeft->iColumn;
      pNew->prereqRight = prereqLeft;
      pNew->prereqAll = prereqAll;
      pNew->operator = operatorMask(pDup->op);
    }
  }

  /* If a term is the BETWEEN operator, create two new virtual terms
  ** that define the range that the BETWEEN implements.
  */
  else if( pExpr->op==TK_BETWEEN ){
    ExprList *pList = pExpr->pList;
    int i;
    static const u8 ops[] = {TK_GE, TK_LE};
    assert( pList!=0 );
    assert( pList->nExpr==2 );
    for(i=0; i<2; i++){
      Expr *pNewExpr;
      WhereTerm *pNewTerm;
      pNewExpr = sqlite3Expr(ops[i], sqlite3ExprDup(pExpr->pLeft),
                             sqlite3ExprDup(pList->a[i].pExpr), 0);
      pNewTerm = whereClauseInsert(pTerm->pWC, pNewExpr,
                                   TERM_VIRTUAL|TERM_DYNAMIC);
      exprAnalyze(pSrc, pMaskSet, pNewTerm);
      pNewTerm->iPartner = pTerm->idx;
    }
    pTerm->nPartner = 2;
  }

  
}


/*
** 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.

static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
  if( pTerm
      && (pTerm->flags & TERM_CODED)==0
      && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
  ){
    pTerm->flags |= TERM_CODED;
    if( pTerm->iPartner>=0 ){
      WhereTerm *pOther = &pTerm->pWC->a[pTerm->iPartner];
      if( (--pOther->nPartner)<=0 ){
        disableTerm(pLevel, pOther);
      }
    }
  }
}

/*
** Generate code that builds a probe for an index.  Details:
**

# 2005 July 28
#
# 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 clauses
# when the WHERE clause contains the BETWEEN operator.
#
# $Id: between.test,v 1.1 2005/07/28 23:12:08 drh Exp $

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

# Build some test data
#
do_test between-1.0 {
  execsql {
    BEGIN;
    CREATE TABLE t1(w int, x int, y int, z int);
  }
  for {set i 1} {$i<=100} {incr i} {
    set w $i
    set x [expr {int(log($i)/log(2))}]
    set y [expr {$i*$i + 2*$i + 1}]
    set z [expr {$x+$y}]
    execsql {INSERT INTO t1 VALUES($::w,$::x,$::y,$::z)}
  }
  execsql {
    CREATE UNIQUE INDEX i1w ON t1(w);
    CREATE INDEX i1xy ON t1(x,y);
    CREATE INDEX i1zyx ON t1(z,y,x);
    COMMIT;
  }
} {}

# This procedure executes the SQL.  Then it appends to the result the
# "sort" or "nosort" keyword depending on whether or not any sorting
# is done.  Then it appends the ::sqlite_query_plan variable.
#
proc queryplan {sql} {
  set ::sqlite_sort_count 0
  set data [execsql $sql]
  if {$::sqlite_sort_count} {set x sort} {set x nosort}
  lappend data $x
  return [concat $data $::sqlite_query_plan]
}

do_test between-1.1.1 {
  queryplan {
    SELECT * FROM t1 WHERE w BETWEEN 5 AND 6 ORDER BY +w
  }
} {5 2 36 38 6 2 49 51 sort t1 i1w}
do_test between-1.1.2 {
  queryplan {
    SELECT * FROM t1 WHERE +w BETWEEN 5 AND 6 ORDER BY +w
  }
} {5 2 36 38 6 2 49 51 sort t1 {}}
do_test between-1.2.1 {
  queryplan {
    SELECT * FROM t1 WHERE w BETWEEN 5 AND 65-y ORDER BY +w
  }
} {5 2 36 38 6 2 49 51 sort t1 i1w}
do_test between-1.2.2 {
  queryplan {
    SELECT * FROM t1 WHERE +w BETWEEN 5 AND 65-y ORDER BY +w
  }
} {5 2 36 38 6 2 49 51 sort t1 {}}
do_test between-1.3.1 {
  queryplan {
    SELECT * FROM t1 WHERE w BETWEEN 41-y AND 6 ORDER BY +w
  }
} {5 2 36 38 6 2 49 51 sort t1 i1w}
do_test between-1.3.2 {
  queryplan {
    SELECT * FROM t1 WHERE +w BETWEEN 41-y AND 6 ORDER BY +w
  }
} {5 2 36 38 6 2 49 51 sort t1 {}}
do_test between-1.4 {
  queryplan {
    SELECT * FROM t1 WHERE w BETWEEN 41-y AND 65-y ORDER BY +w
  }
} {5 2 36 38 6 2 49 51 sort t1 {}}
do_test between-1.5.1 {
  queryplan {
    SELECT * FROM t1 WHERE 26 BETWEEN y AND z ORDER BY +w
  }
} {4 2 25 27 sort t1 i1zyx}
do_test between-1.5.2 {
  queryplan {
    SELECT * FROM t1 WHERE 26 BETWEEN +y AND z ORDER BY +w
  }
} {4 2 25 27 sort t1 i1zyx}
do_test between-1.5.3 {
  queryplan {
    SELECT * FROM t1 WHERE 26 BETWEEN y AND +z ORDER BY +w
  }
} {4 2 25 27 sort t1 {}}


finish_test

#    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 clauses
# based on recent changes to the optimizer.
#
# $Id: where2.test,v 1.2 2005/07/28 23:12:08 drh Exp $

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

# Build some test data
#
do_test where2-1.0 {

  }
} {99 6 10000 10006 nosort t1 i1w}
do_test where2-5.2 {
  queryplan {
    SELECT * FROM t1 WHERE w IN (99) ORDER BY w
  }
} {99 6 10000 10006 sort t1 i1w}


integrity_check {where2-99.0}

finish_test