SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.317 2006/06/20 13:07:27 danielk1977 Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.

      assert( pFrom->pTab==0 );
      pFrom->pTab = pTab = 
        sqlite3LocateTable(pParse,pFrom->zName,pFrom->zDatabase);
      if( pTab==0 ){
        return 1;
      }
      pTab->nRef++;
#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
      if( pTab->pSelect || IsVirtual(pTab) ){
        /* We reach here if the named table is a really a view */
        if( sqlite3ViewGetColumnNames(pParse, pTab) ){
          return 1;
        }
        /* If pFrom->pSelect!=0 it means we are dealing with a
        ** view within a view.  The SELECT structure has already been
        ** copied by the outer view so we can skip the copy step here

** 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 1.221 2006/06/20 13:07:28 danielk1977 Exp $
*/
#include "sqliteInt.h"

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

  if( pIdxInfo->needToFreeIdxStr ){
    sqlite3_free(pIdxInfo->idxStr);
  }
  pIdxInfo->idxStr = 0;
  pIdxInfo->idxNum = 0;
  pIdxInfo->needToFreeIdxStr = 0;
  pIdxInfo->orderByConsumed = 0;
  pIdxInfo->estimatedCost = SQLITE_BIG_DBL / 2.0;
  nOrderBy = pIdxInfo->nOrderBy;
  if( pIdxInfo->nOrderBy && !orderByUsable ){
    *(int*)&pIdxInfo->nOrderBy = 0;
  }

  sqlite3SafetyOff(pParse->db);
  pTab->pVtab->pModule->xBestIndex(pTab->pVtab, pIdxInfo);

    Index *pBest = 0;           /* The best index seen so far */
    int bestFlags = 0;          /* Flags associated with pBest */
    int bestNEq = 0;            /* nEq associated with pBest */
    double lowestCost;          /* Cost of the pBest */
    int bestJ = 0;              /* The value of j */
    Bitmask m;                  /* Bitmask value for j or bestJ */
    int once = 0;               /* True when first table is seen */
    sqlite3_index_info *pBestIndex = 0;
    sqlite3_index_info *pIndex = 0;

    lowestCost = SQLITE_BIG_DBL;
    for(j=iFrom, pTabItem=&pTabList->a[j]; j<pTabList->nSrc; j++, pTabItem++){
      int doNotReorder;  /* True if this table should not be reordered */

      doNotReorder =  (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0
                   || (j>0 && (pTabItem[-1].jointype & (JT_LEFT|JT_CROSS))!=0);
      if( once && doNotReorder ) break;
      m = getMask(&maskSet, pTabItem->iCursor);
      if( (m & notReady)==0 ){
        if( j==iFrom ) iFrom++;
        continue;
      }
      assert( pTabItem->pTab );
#ifndef SQLITE_OMIT_VIRTUALTABLE
      if( IsVirtual(pTabItem->pTab) ){
        cost = bestVirtualIndex(pParse, &wc, pTabItem, notReady,
                                ppOrderBy ? *ppOrderBy : 0, i==0,
                                &pIndex);
        flags = WHERE_VIRTUALTABLE;
        if( pIndex && pIndex->orderByConsumed ){
          flags = WHERE_VIRTUALTABLE | WHERE_ORDERBY;
        }
        pIdx = 0;
        nEq = 0;
      }else 
#endif
      {
        cost = bestIndex(pParse, &wc, pTabItem, notReady,
                         (i==0 && ppOrderBy) ? *ppOrderBy : 0,
                         &pIdx, &flags, &nEq);
      }
      if( cost<lowestCost ){
        once = 1;
        lowestCost = cost;
        pBest = pIdx;
        bestFlags = flags;
        bestNEq = nEq;
        bestJ = j;
#ifndef SQLITE_OMIT_VIRTUALTABLE
        sqliteFree(pBestIndex);
        pBestIndex = pIndex;
        pIndex = 0;
      }else{
        sqliteFree(pIndex);
        pIndex = 0;
#endif
      }
      if( doNotReorder ) break;
    }
    TRACE(("*** Optimizer choose table %d for loop %d\n", bestJ,
           pLevel-pWInfo->a));
    if( (bestFlags & WHERE_ORDERBY)!=0 ){
      *ppOrderBy = 0;
    }
    andFlags &= bestFlags;
    pLevel->flags = bestFlags;
    pLevel->pIdx = pBest;
    pLevel->nEq = bestNEq;
    pLevel->aInLoop = 0;
    pLevel->nIn = 0;
    pLevel->pIdxInfo = pBestIndex;
    if( pBest ){
      pLevel->iIdxCur = pParse->nTab++;
    }else{
      pLevel->iIdxCur = -1;
    }
    notReady &= ~getMask(&maskSet, pTabList->a[bestJ].iCursor);
    pLevel->iFrom = bestJ;

#endif /* SQLITE_OMIT_EXPLAIN */
    pTabItem = &pTabList->a[pLevel->iFrom];
    pTab = pTabItem->pTab;
    iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
    if( pTab->isEphem || pTab->pSelect ) continue;
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( pLevel->pIdxInfo ){
      int iCur = pTabItem->iCursor;
      sqlite3VdbeOp3(v, OP_VOpen, iCur, 0, (const char*)pTab->pVtab, P3_VTAB);
    }else
#endif
    if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
      sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, OP_OpenRead);
      if( pTab->nCol<(sizeof(Bitmask)*8) ){
        Bitmask b = pTabItem->colUsed;
        int n = 0;

    }

#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( pLevel->pIdxInfo ){
      /* Case 0:  The table is a virtual-table.  Use the VFilter and VNext
      **          to access the data.
      */
      int ii;
      sqlite3_index_info *pIdxInfo = pLevel->pIdxInfo;
      int nConstraint = pIdxInfo->nConstraint;
      struct sqlite3_index_constraint_usage *aUsage =
                                                  pIdxInfo->aConstraintUsage;
      const struct sqlite3_index_constraint *aConstraint =
                                                  pIdxInfo->aConstraint;

      for(ii=1; ii<=nConstraint; ii++){
        int j;
        for(j=0; j<nConstraint; j++){
          if( aUsage[j].argvIndex==ii ){
            int k = aConstraint[j].iTermOffset;
            sqlite3ExprCode(pParse, wc.a[k].pExpr->pRight);
            break;
          }
        }
        if( j==nConstraint ) break;
      }
      sqlite3VdbeAddOp(v, OP_Integer, ii-1, 0);
      sqlite3VdbeAddOp(v, OP_Integer, pIdxInfo->idxNum, 0);
      sqlite3VdbeOp3(v, OP_VFilter, iCur, brk, pIdxInfo->idxStr,
                      pIdxInfo->needToFreeIdxStr ? P3_MPRINTF : P3_STATIC);
      pIdxInfo->needToFreeIdxStr = 0;
      for(ii=0; ii<pIdxInfo->nConstraint; ii++){
        if( pIdxInfo->aConstraintUsage[ii].omit ){
          disableTerm(pLevel, &wc.a[ii]);
        }
      }
      pLevel->op = OP_VNext;
      pLevel->p1 = iCur;
      pLevel->p2 = sqlite3VdbeCurrentAddr(v);
    }else
#endif /* SQLITE_OMIT_VIRTUALTABLE */

# 2006 June 10
#
# 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 creating and dropping virtual tables.
#
# $Id: vtab1.test,v 1.24 2006/06/20 13:07:28 danielk1977 Exp $

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

ifcapable !vtab||!schema_pragmas {
  finish_test
  return

do_test vtab1-2.5 {
  set echo_module ""
  execsql {
    DROP TABLE t1;
  }
  set echo_module
} {xDestroy}


do_test vtab1-2.6 {
  execsql { 
    PRAGMA table_info(t1); 
  }
} {}
do_test vtab1-2.7 {

} [list xBestIndex {SELECT rowid, * FROM 'treal'} \
        xFilter    {SELECT rowid, * FROM 'treal'} ]

execsql {
  DROP TABLE t1;
  DROP TABLE treal;
}

#----------------------------------------------------------------------
# Test cases vtab1-5 test SELECT queries that include joins on virtual 
# tables.

proc filter {log} {
  set out [list]
  for {set ii 0} {$ii < [llength $log]} {incr ii} {
    if {[lindex $log $ii] eq "xFilter"} {
      lappend out xFilter
      lappend out [lindex $log [expr $ii+1]]
    }
  }
  return $out
}

do_test vtab1-5-1 {
  execsql { 
    CREATE TABLE t1(a, b, c);
    CREATE TABLE t2(d, e, f);
    INSERT INTO t1 VALUES(1, 'red', 'green');
    INSERT INTO t1 VALUES(2, 'blue', 'black');
    INSERT INTO t2 VALUES(1, 'spades', 'clubs');
    INSERT INTO t2 VALUES(2, 'hearts', 'diamonds');
    CREATE VIRTUAL TABLE et1 USING echo(t1);
    CREATE VIRTUAL TABLE et2 USING echo(t2);
  }
} {}

do_test vtab1-5-2 {
  set echo_module ""
  execsql {
    SELECT * FROM et1, et2;
  }
} [list \
  1 red green 1 spades clubs     \
  1 red green 2 hearts diamonds  \
  2 blue black 1 spades clubs    \
  2 blue black 2 hearts diamonds \
]
do_test vtab1-5-3 {
  filter $echo_module
} [list \
  xFilter {SELECT rowid, * FROM 't1'} \
  xFilter {SELECT rowid, * FROM 't2'} \
  xFilter {SELECT rowid, * FROM 't2'} \
]
do_test vtab1-5-4 {
  set echo_module ""
  execsql {
    SELECT * FROM et1, et2 WHERE et2.d = 2;
  }
} [list \
  1 red green 2 hearts diamonds  \
  2 blue black 2 hearts diamonds \
]
do_test vtab1-5-5 {
  filter $echo_module
} [list \
  xFilter {SELECT rowid, * FROM 't1'} \
  xFilter {SELECT rowid, * FROM 't2'} \
  xFilter {SELECT rowid, * FROM 't2'} \
]
do_test vtab1-5-6 {
  execsql {
    CREATE INDEX i1 ON t2(d);
  }

  db close
  sqlite3 db test.db
  register_echo_module [sqlite3_connection_pointer db]

  set echo_module ""
  execsql {
    SELECT * FROM et1, et2 WHERE et2.d = 2;
  }
} [list \
  1 red green 2 hearts diamonds  \
  2 blue black 2 hearts diamonds \
]
do_test vtab1-5-7 {
  filter $echo_module
} [list \
  xFilter {SELECT rowid, * FROM 't2' WHERE d = ?} \
  xFilter {SELECT rowid, * FROM 't1'}             \
]

execsql {
  DROP TABLE t1;
  DROP TABLE t2;
  DROP TABLE et1;
  DROP TABLE et2;
}

#----------------------------------------------------------------------
# Test cases vtab1-6 test INSERT, UPDATE and DELETE operations 
# on virtual tables.
do_test vtab1-6-1 {
  execsql { SELECT sql FROM sqlite_master }
} {}