SQLite

** that actually generate the bulk of the WHERE loop code.  The original where.c
** file retains the code that does query planning and analysis.
*/
#include "sqliteInt.h"
#include "whereInt.h"

#ifndef SQLITE_OMIT_EXPLAIN

/*
** Return the name of the i-th column of the pIdx index.
*/
static const char *explainIndexColumnName(Index *pIdx, int i){
  i = pIdx->aiColumn[i];
  if( i==XN_EXPR ) return "<expr>";
  if( i==XN_ROWID ) return "rowid";
  return pIdx->pTable->aCol[i].zName;
}

/*
** This routine is a helper for explainIndexRange() below
**
** pStr holds the text of an expression that we are building up one term
** at a time.  This routine adds a new term to the end of the expression.
** Terms are separated by AND so add the "AND" text for second and subsequent
** terms only.
*/
static void explainAppendTerm(
  StrAccum *pStr,             /* The text expression being built */
  Index *pIdx,                /* Index to read column names from */
  int nTerm,                  /* Number of terms */
  int iTerm,                  /* Zero-based index of first term. */
  int bAnd,                   /* Non-zero to append " AND " */
  const char *zOp             /* Name of the operator */
){
  int i;

  assert( nTerm>=1 );
  if( bAnd ) sqlite3StrAccumAppend(pStr, " AND ", 5);

  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, "(", 1);
  for(i=0; i<nTerm; i++){
    if( i ) sqlite3StrAccumAppend(pStr, ",", 1);
    sqlite3StrAccumAppendAll(pStr, explainIndexColumnName(pIdx, iTerm+i));
  }
  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, ")", 1);

  sqlite3StrAccumAppend(pStr, zOp, 1);

  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, "(", 1);
  for(i=0; i<nTerm; i++){
    if( i ) sqlite3StrAccumAppend(pStr, ",", 1);
    sqlite3StrAccumAppend(pStr, "?", 1);
  }





  if( nTerm>1 ) sqlite3StrAccumAppend(pStr, ")", 1);


}

/*
** Argument pLevel describes a strategy for scanning table pTab. This 
** function appends text to pStr that describes the subset of table
** rows scanned by the strategy in the form of an SQL expression.
**

    const char *z = explainIndexColumnName(pIndex, i);
    if( i ) sqlite3StrAccumAppend(pStr, " AND ", 5);
    sqlite3XPrintf(pStr, i>=nSkip ? "%s=?" : "ANY(%s)", z);
  }

  j = i;
  if( pLoop->wsFlags&WHERE_BTM_LIMIT ){

    explainAppendTerm(pStr, pIndex, pLoop->u.btree.nBtm, j, i, ">");
    i = 1;
  }
  if( pLoop->wsFlags&WHERE_TOP_LIMIT ){

    explainAppendTerm(pStr, pIndex, pLoop->u.btree.nTop, j, i, "<");
  }
  sqlite3StrAccumAppend(pStr, ")", 1);
}

/*
** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
** command, or if either SQLITE_DEBUG or SQLITE_ENABLE_STMT_SCANSTATUS was

  do_eqp_test 3.2.3 { SELECT * FROM c1 WHERE a=1 AND c>=1 } {
    0 0 0 {SEARCH TABLE c1 USING INDEX c1ab (a=?)}
  }
  do_eqp_test 3.2.4 { SELECT * FROM c1 WHERE a=1 AND (c, d)>(1, 'c') } {
    0 0 0 {SEARCH TABLE c1 USING INDEX c1ab (a=?)}
  }
  do_eqp_test 3.2.5 { SELECT * FROM c1 WHERE a=1 AND (c, d)>(1, 'o') } {
    0 0 0 {SEARCH TABLE c1 USING INDEX c1cd ((c,d)>(?,?))}
  }
  do_eqp_test 3.2.6 { SELECT * FROM c1 WHERE a=1 AND (c, +b)>(1, 'c') } {
    0 0 0 {SEARCH TABLE c1 USING INDEX c1ab (a=?)}
  }
}

#------------------------------------------------------------------------

} {
  0 0 0 {SEARCH TABLE d2 USING INDEX d2ab (a=? AND b=?)}
  0 0 0 {EXECUTE LIST SUBQUERY 1} 
  1 0 0 {SCAN TABLE d1}
  0 0 0 {EXECUTE LIST SUBQUERY 2} 
  2 0 0 {SCAN TABLE d1}
}

do_execsql_test 6.0 {
  CREATE TABLE e1(a, b, c, d, e);
  CREATE INDEX e1ab ON e1(a, b);
  CREATE INDEX e1cde ON e1(c, d, e);
}

do_eqp_test 6.1 {
  SELECT * FROM e1 WHERE (a, b) > (?, ?)
} {
  0 0 0 {SEARCH TABLE e1 USING INDEX e1ab ((a,b)>(?,?))}
}
do_eqp_test 6.2 {
  SELECT * FROM e1 WHERE (a, b) < (?, ?)
} {
  0 0 0 {SEARCH TABLE e1 USING INDEX e1ab ((a,b)<(?,?))}
}
do_eqp_test 6.3 {
  SELECT * FROM e1 WHERE c = ? AND (d, e) > (?, ?)
} {
  0 0 0 {SEARCH TABLE e1 USING INDEX e1cde (c=? AND (d,e)>(?,?))}
}
do_eqp_test 6.4 {
  SELECT * FROM e1 WHERE c = ? AND (d, e) < (?, ?)
} {
  0 0 0 {SEARCH TABLE e1 USING INDEX e1cde (c=? AND (d,e)<(?,?))}
}

do_eqp_test 6.5 {
  SELECT * FROM e1 WHERE (d, e) BETWEEN (?, ?) AND (?, ?) AND c = ?
} {
  0 0 0 
  {SEARCH TABLE e1 USING INDEX e1cde (c=? AND (d,e)>(?,?) AND (d,e)<(?,?))}
}


finish_test