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 1.504 2009/02/25 08:56:47 danielk1977 Exp $
*/
#include "sqliteInt.h"


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

  assert( !p->pGroupBy );

  if( p->pWhere || p->pEList->nExpr!=1 
   || p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect
  ){
    return 0;
  }

  pTab = p->pSrc->a[0].pTab;
  pExpr = p->pEList->a[0].pExpr;
  assert( pTab && !pTab->pSelect && pExpr );

  if( IsVirtual(pTab) ) return 0;
  if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
  if( (pAggInfo->aFunc[0].pFunc->flags&SQLITE_FUNC_COUNT)==0 ) return 0;
  if( pExpr->flags&EP_Distinct ) return 0;

  return pTab;
}

# 2009 February 24
#
# 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 count(*)" statements.
#
# $Id: count.test,v 1.3 2009/02/25 08:56:47 danielk1977 Exp $

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

# Test plan:
#
#  count-1.*: Test that the OP_Count instruction appears to work on both

} {0}
do_test count-2.12 {
  uses_op_count {SELECT count(*), max(a) FROM t2}
} {0}
do_test count-2.13 {
  uses_op_count {SELECT count(*) FROM t1, t2}
} {0}

ifcapable vtab {
  register_echo_module [sqlite3_connection_pointer db]
  do_test count-2.14 {
    execsql { CREATE VIRTUAL TABLE techo USING echo(t1); }
    uses_op_count {SELECT count(*) FROM techo}
  } {0}
}

do_test count-3.1 {
  execsql {
    CREATE TABLE t3(a, b);
    SELECT a FROM (SELECT count(*) AS a FROM t3) WHERE a==0;
  }
} {0}
do_test count-3.2 {
  execsql {
    SELECT a FROM (SELECT count(*) AS a FROM t3) WHERE a==1;
  }
} {}

do_test count-4.1 {
  execsql {
    CREATE TABLE t4(a, b);
    INSERT INTO t4 VALUES('a', 'b');
    CREATE INDEX t4i1 ON t4(b, a);
    SELECT count(*) FROM t4;
  }
} {1}
do_test count-4.2 {
  execsql {
    CREATE INDEX t4i2 ON t4(b);
    SELECT count(*) FROM t4;
  }
} {1}
do_test count-4.3 {
  execsql {
    DROP INDEX t4i1;
    CREATE INDEX t4i1 ON t4(b, a);
    SELECT count(*) FROM t4;
  }
} {1}


finish_test

# This file attempts to check the behavior of the SQLite library in 
# an out-of-memory situation. When compiled with -DSQLITE_DEBUG=1, 
# the SQLite library accepts a special command (sqlite3_memdebug_fail N C)
# which causes the N-th malloc to fail.  This special feature is used
# to see what happens in the library if a malloc were to really fail
# due to an out-of-memory situation.
#
# $Id: malloc.test,v 1.76 2009/02/25 08:56:47 danielk1977 Exp $

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


# Only run these tests if memory debugging is turned on.
#

  set zRepeat "transient"
  if {$::iRepeat} {set zRepeat "persistent"}
  do_test malloc-32.$zRepeat.${::n}.integrity {
    execsql {PRAGMA integrity_check} db2
  } {ok}
  db2 close
}

# The following two OOM tests verify that OOM handling works in the
# code used to optimize "SELECT count(*) FROM <tbl>".
#
do_malloc_test 33 -tclprep {
  db eval { PRAGMA cache_size = 10 }
  db transaction {
    db eval { CREATE TABLE abc(a, b) }
    for {set i 0} {$i<500} {incr i} {
      db eval {INSERT INTO abc VALUES(randstr(100,100), randstr(1000,1000))}
    }
  }
} -sqlbody {
  SELECT count(*) FROM abc;
}
do_malloc_test 34 -tclprep {
  db eval { PRAGMA cache_size = 10 }
  db transaction {
    db eval { CREATE TABLE abc(a PRIMARY KEY, b) }
    for {set i 0} {$i<500} {incr i} {
      db eval {INSERT INTO abc VALUES(randstr(100,100), randstr(1000,1000))}
    }
  }
} -sqlbody {
  SELECT count(*) FROM abc;
}

# Ensure that no file descriptors were leaked.
do_test malloc-99.X {
  catch {db close}
  set sqlite_open_file_count
} {0}

puts open-file-count=$sqlite_open_file_count
finish_test