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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Artifact 1bc0381538fd21f96a10dbabc10ffc51b5b2e5f412d34bae571273ca784003d7:


# 2014-04-21
#
# 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.
#
#*************************************************************************
#
# Test that ticket [b75a9ca6b0] has been fixed.
#
# Ticket [b75a9ca6b0] concerns queries that have both a GROUP BY
# and an ORDER BY.  This code verifies that SQLite is able to
# optimize out the ORDER BY in some circumstances, but retains the
# ORDER BY when necessary.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix tkt-b75a9ca6b0

do_execsql_test 1 {
  CREATE TABLE t1 (x, y);
  INSERT INTO t1 VALUES (1, 3); 
  INSERT INTO t1 VALUES (2, 2);
  INSERT INTO t1 VALUES (3, 1);
}

do_execsql_test 1.1 {
  CREATE INDEX i1 ON t1(x, y);
} 

set idxscan {SCAN TABLE t1 USING COVERING INDEX i1}
set tblscan {SCAN TABLE t1}
set grpsort {USE TEMP B-TREE FOR GROUP BY}
set sort    {USE TEMP B-TREE FOR ORDER BY}

foreach {tn q res eqp} [subst -nocommands {
  1 "SELECT * FROM t1 GROUP BY x, y ORDER BY x,y"
  {1 3  2 2  3 1} {$idxscan}

  2 "SELECT * FROM t1 GROUP BY x, y ORDER BY x"
  {1 3  2 2  3 1} {$idxscan*$sort}

  3 "SELECT * FROM t1 GROUP BY y, x ORDER BY y, x"
  {3 1  2 2  1 3} {$idxscan*$sort}
  
  4 "SELECT * FROM t1 GROUP BY x ORDER BY x"
  {1 3  2 2  3 1} {$idxscan}

  5 "SELECT * FROM t1 GROUP BY y ORDER BY y"
  {3 1  2 2  1 3} {$tblscan*$grpsort}

  6 "SELECT * FROM t1 GROUP BY y ORDER BY x"
  {1 3  2 2  3 1} {$tblscan*$grpsort*$sort}

  7 "SELECT * FROM t1 GROUP BY x, y ORDER BY x, y DESC"
  {1 3  2 2  3 1} {$idxscan*$sort}

  8 "SELECT * FROM t1 GROUP BY x, y ORDER BY x DESC, y DESC"
  {3 1  2 2  1 3} {$idxscan*$sort}

  9 "SELECT * FROM t1 GROUP BY x, y ORDER BY x ASC, y ASC"
  {1 3  2 2  3 1} {$idxscan}

  10 "SELECT * FROM t1 GROUP BY x, y ORDER BY x COLLATE nocase, y"
  {1 3  2 2  3 1} {$idxscan*$sort}

}] {
  do_execsql_test 1.$tn.1 $q $res
  do_eqp_test     1.$tn.2 $q $eqp
}


finish_test