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Overview
Comment:Get the min/max optimization working with descending indices. Ticket #2514. (CVS 4161)
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: a80a3c9d0a5e0a8a3d67bd841e2076893fd5e9aa
User & Date: drh 2007-07-18 18:17:12
Context
2007-07-19
12:41
Clarify the documentation on the nByte parameter to sqlite3_prepare(). Make it clear that nByte is a maximum string length. Ticket #2516. (CVS 4162) check-in: d1ae3de4 user: drh tags: trunk
2007-07-18
18:17
Get the min/max optimization working with descending indices. Ticket #2514. (CVS 4161) check-in: a80a3c9d user: drh tags: trunk
18:16
Additional diagnostics added to the "out" file generated by lemon. (CVS 4160) check-in: 7ef2aaf7 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/select.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 C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.353 2007/06/26 10:38:55 danielk1977 Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
................................................................................
    sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
    sqlite3VdbeOp3(v, OP_OpenRead, iIdx, pIdx->tnum, 
        (char*)pKey, P3_KEYINFO_HANDOFF);
    if( seekOp==OP_Rewind ){
      sqlite3VdbeAddOp(v, OP_Null, 0, 0);
      sqlite3VdbeAddOp(v, OP_MakeRecord, 1, 0);
      seekOp = OP_MoveGt;










    }
    sqlite3VdbeAddOp(v, seekOp, iIdx, 0);
    sqlite3VdbeAddOp(v, OP_IdxRowid, iIdx, 0);
    sqlite3VdbeAddOp(v, OP_Close, iIdx, 0);
    sqlite3VdbeAddOp(v, OP_MoveGe, base, 0);
  }
  eList.nExpr = 1;







|







 







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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 C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.354 2007/07/18 18:17:12 drh Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
................................................................................
    sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
    sqlite3VdbeOp3(v, OP_OpenRead, iIdx, pIdx->tnum, 
        (char*)pKey, P3_KEYINFO_HANDOFF);
    if( seekOp==OP_Rewind ){
      sqlite3VdbeAddOp(v, OP_Null, 0, 0);
      sqlite3VdbeAddOp(v, OP_MakeRecord, 1, 0);
      seekOp = OP_MoveGt;
    }
    if( pIdx->aSortOrder[0]==SQLITE_SO_DESC ){
      /* Ticket #2514: invert the seek operator if we are using
      ** a descending index. */
      if( seekOp==OP_Last ){
        seekOp = OP_Rewind;
      }else{
        assert( seekOp==OP_MoveGt );
        seekOp = OP_MoveLt;
      }
    }
    sqlite3VdbeAddOp(v, seekOp, iIdx, 0);
    sqlite3VdbeAddOp(v, OP_IdxRowid, iIdx, 0);
    sqlite3VdbeAddOp(v, OP_Close, iIdx, 0);
    sqlite3VdbeAddOp(v, OP_MoveGe, base, 0);
  }
  eList.nExpr = 1;

Added test/minmax2.test.







































































































































































































































































































































































































































































































































































































































































































































































































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# 2007 July 17
#
# 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 SELECT statements that contain
# aggregate min() and max() functions and which are handled as
# as a special case.  This file makes sure that the min/max
# optimization works right in the presence of descending
# indices.  Ticket #2514.
#
# $Id: minmax2.test,v 1.1 2007/07/18 18:17:12 drh Exp $

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

do_test minmax2-1.0 {
  execsql {
    PRAGMA legacy_file_format=0;
    BEGIN;
    CREATE TABLE t1(x, y);
    INSERT INTO t1 VALUES(1,1);
    INSERT INTO t1 VALUES(2,2);
    INSERT INTO t1 VALUES(3,2);
    INSERT INTO t1 VALUES(4,3);
    INSERT INTO t1 VALUES(5,3);
    INSERT INTO t1 VALUES(6,3);
    INSERT INTO t1 VALUES(7,3);
    INSERT INTO t1 VALUES(8,4);
    INSERT INTO t1 VALUES(9,4);
    INSERT INTO t1 VALUES(10,4);
    INSERT INTO t1 VALUES(11,4);
    INSERT INTO t1 VALUES(12,4);
    INSERT INTO t1 VALUES(13,4);
    INSERT INTO t1 VALUES(14,4);
    INSERT INTO t1 VALUES(15,4);
    INSERT INTO t1 VALUES(16,5);
    INSERT INTO t1 VALUES(17,5);
    INSERT INTO t1 VALUES(18,5);
    INSERT INTO t1 VALUES(19,5);
    INSERT INTO t1 VALUES(20,5);
    COMMIT;
    SELECT DISTINCT y FROM t1 ORDER BY y;
  }
} {1 2 3 4 5}

do_test minmax2-1.1 {
  set sqlite_search_count 0
  execsql {SELECT min(x) FROM t1}
} {1}
do_test minmax2-1.2 {
  set sqlite_search_count
} {19}
do_test minmax2-1.3 {
  set sqlite_search_count 0
  execsql {SELECT max(x) FROM t1}
} {20}
do_test minmax2-1.4 {
  set sqlite_search_count
} {19}
do_test minmax2-1.5 {
  execsql {CREATE INDEX t1i1 ON t1(x DESC)}
  set sqlite_search_count 0
  execsql {SELECT min(x) FROM t1}
} {1}
do_test minmax2-1.6 {
  set sqlite_search_count
} {2}
do_test minmax2-1.7 {
  set sqlite_search_count 0
  execsql {SELECT max(x) FROM t1}
} {20}
do_test minmax2-1.8 {
  set sqlite_search_count
} {1}
do_test minmax2-1.9 {
  set sqlite_search_count 0
  execsql {SELECT max(y) FROM t1}
} {5}
do_test minmax2-1.10 {
  set sqlite_search_count
} {19}

do_test minmax2-2.0 {
  execsql {
    CREATE TABLE t2(a INTEGER PRIMARY KEY, b);
    INSERT INTO t2 SELECT * FROM t1;
  }
  set sqlite_search_count 0
  execsql {SELECT min(a) FROM t2}
} {1}
do_test minmax2-2.1 {
  set sqlite_search_count
} {0}
do_test minmax2-2.2 {
  set sqlite_search_count 0
  execsql {SELECT max(a) FROM t2}
} {20}
do_test minmax2-2.3 {
  set sqlite_search_count
} {0}

do_test minmax2-3.0 {
  ifcapable subquery {
    execsql {INSERT INTO t2 VALUES((SELECT max(a) FROM t2)+1,999)}
  } else {
    db function max_a_t2 {execsql {SELECT max(a) FROM t2}}
    execsql {INSERT INTO t2 VALUES(max_a_t2()+1,999)}
  }
  set sqlite_search_count 0
  execsql {SELECT max(a) FROM t2}
} {21}
do_test minmax2-3.1 {
  set sqlite_search_count
} {0}
do_test minmax2-3.2 {
  ifcapable subquery {
    execsql {INSERT INTO t2 VALUES((SELECT max(a) FROM t2)+1,999)}
  } else {
    db function max_a_t2 {execsql {SELECT max(a) FROM t2}}
    execsql {INSERT INTO t2 VALUES(max_a_t2()+1,999)}
  }
  set sqlite_search_count 0
  ifcapable subquery {
    execsql { SELECT b FROM t2 WHERE a=(SELECT max(a) FROM t2) }
  } else {
    execsql { SELECT b FROM t2 WHERE a=max_a_t2() }
  }
} {999}
do_test minmax2-3.3 {
  set sqlite_search_count
} {0}

ifcapable {compound && subquery} {
  do_test minmax2-4.1 {
    execsql {
      SELECT coalesce(min(x+0),-1), coalesce(max(x+0),-1) FROM
        (SELECT * FROM t1 UNION SELECT NULL as 'x', NULL as 'y')
    }
  } {1 20}
  do_test minmax2-4.2 {
    execsql {
      SELECT y, coalesce(sum(x),0) FROM
        (SELECT null AS x, y+1 AS y FROM t1 UNION SELECT * FROM t1)
      GROUP BY y ORDER BY y;
    }
  } {1 1 2 5 3 22 4 92 5 90 6 0}
  do_test minmax2-4.3 {
    execsql {
      SELECT y, count(x), count(*) FROM
        (SELECT null AS x, y+1 AS y FROM t1 UNION SELECT * FROM t1)
      GROUP BY y ORDER BY y;
    }
  } {1 1 1 2 2 3 3 4 5 4 8 9 5 5 6 6 0 1}
} ;# ifcapable compound

# Make sure the min(x) and max(x) optimizations work on empty tables
# including empty tables with indices. Ticket #296.
#
do_test minmax2-5.1 {
  execsql {
    CREATE TABLE t3(x INTEGER UNIQUE NOT NULL);
    SELECT coalesce(min(x),999) FROM t3;
  }
} {999}
do_test minmax2-5.2 {
  execsql {
    SELECT coalesce(min(rowid),999) FROM t3;
  }
} {999}
do_test minmax2-5.3 {
  execsql {
    SELECT coalesce(max(x),999) FROM t3;
  }
} {999}
do_test minmax2-5.4 {
  execsql {
    SELECT coalesce(max(rowid),999) FROM t3;
  }
} {999}
do_test minmax2-5.5 {
  execsql {
    SELECT coalesce(max(rowid),999) FROM t3 WHERE rowid<25;
  }
} {999}

# Make sure the min(x) and max(x) optimizations work when there
# is a LIMIT clause.  Ticket #396.
#
do_test minmax2-6.1 {
  execsql {
    SELECT min(a) FROM t2 LIMIT 1
  }
} {1}
do_test minmax2-6.2 {
  execsql {
    SELECT max(a) FROM t2 LIMIT 3
  }
} {22}
do_test minmax2-6.3 {
  execsql {
    SELECT min(a) FROM t2 LIMIT 0,100
  }
} {1}
do_test minmax2-6.4 {
  execsql {
    SELECT max(a) FROM t2 LIMIT 1,100
  }
} {}
do_test minmax2-6.5 {
  execsql {
    SELECT min(x) FROM t3 LIMIT 1
  }
} {{}}
do_test minmax2-6.6 {
  execsql {
    SELECT max(x) FROM t3 LIMIT 0
  }
} {}
do_test minmax2-6.7 {
  execsql {
    SELECT max(a) FROM t2 LIMIT 0
  }
} {}

# Make sure the max(x) and min(x) optimizations work for nested
# queries.  Ticket #587.
#
do_test minmax2-7.1 {
  execsql {
    SELECT max(x) FROM t1;
  }
} 20
ifcapable subquery {
  do_test minmax2-7.2 {
    execsql {
      SELECT * FROM (SELECT max(x) FROM t1);
    }
  } 20
}
do_test minmax2-7.3 {
  execsql {
    SELECT min(x) FROM t1;
  }
} 1
ifcapable subquery {
  do_test minmax2-7.4 {
    execsql {
      SELECT * FROM (SELECT min(x) FROM t1);
    }
  } 1
}

# Make sure min(x) and max(x) work correctly when the datatype is
# TEXT instead of NUMERIC.  Ticket #623.
#
do_test minmax2-8.1 {
  execsql {
    CREATE TABLE t4(a TEXT);
    INSERT INTO t4 VALUES('1234');
    INSERT INTO t4 VALUES('234');
    INSERT INTO t4 VALUES('34');
    SELECT min(a), max(a) FROM t4;
  }
} {1234 34}
do_test minmax2-8.2 {
  execsql {
    CREATE TABLE t5(a INTEGER);
    INSERT INTO t5 VALUES('1234');
    INSERT INTO t5 VALUES('234');
    INSERT INTO t5 VALUES('34');
    SELECT min(a), max(a) FROM t5;
  }
} {34 1234}

# Ticket #658:  Test the min()/max() optimization when the FROM clause
# is a subquery.
#
ifcapable {compound && subquery} {
  do_test minmax2-9.1 {
    execsql {
      SELECT max(rowid) FROM (
        SELECT max(rowid) FROM t4 UNION SELECT max(rowid) FROM t5
      )
    }
  } {1}
  do_test minmax2-9.2 {
    execsql {
      SELECT max(rowid) FROM (
        SELECT max(rowid) FROM t4 EXCEPT SELECT max(rowid) FROM t5
      )
    }
  } {{}}
} ;# ifcapable compound&&subquery

# If there is a NULL in an aggregate max() or min(), ignore it.  An
# aggregate min() or max() will only return NULL if all values are NULL.
#
do_test minmax2-10.1 {
  execsql {
    CREATE TABLE t6(x);
    INSERT INTO t6 VALUES(1);
    INSERT INTO t6 VALUES(2);
    INSERT INTO t6 VALUES(NULL);
    SELECT coalesce(min(x),-1) FROM t6;
  }
} {1}
do_test minmax2-10.2 {
  execsql {
    SELECT max(x) FROM t6;
  }
} {2}
do_test minmax2-10.3 {
  execsql {
    CREATE INDEX i6 ON t6(x DESC);
    SELECT coalesce(min(x),-1) FROM t6;
  }
} {1}
do_test minmax2-10.4 {
  execsql {
    SELECT max(x) FROM t6;
  }
} {2}
do_test minmax2-10.5 {
  execsql {
    DELETE FROM t6 WHERE x NOT NULL;
    SELECT count(*) FROM t6;
  }
} 1
do_test minmax2-10.6 {
  execsql {
    SELECT count(x) FROM t6;
  }
} 0
ifcapable subquery {
  do_test minmax2-10.7 {
    execsql {
      SELECT (SELECT min(x) FROM t6), (SELECT max(x) FROM t6);
    }
  } {{} {}}
}
do_test minmax2-10.8 {
  execsql {
    SELECT min(x), max(x) FROM t6;
  }
} {{} {}}
do_test minmax2-10.9 {
  execsql {
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    INSERT INTO t6 SELECT * FROM t6;
    SELECT count(*) FROM t6;
  }
} 1024
do_test minmax2-10.10 {
  execsql {
    SELECT count(x) FROM t6;
  }
} 0
ifcapable subquery {
  do_test minmax2-10.11 {
    execsql {
      SELECT (SELECT min(x) FROM t6), (SELECT max(x) FROM t6);
    }
  } {{} {}}
}
do_test minmax2-10.12 {
  execsql {
    SELECT min(x), max(x) FROM t6;
  }
} {{} {}}


finish_test