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Overview
Comment:Change an OP_SCopy into an OP_Copy in a case where the destination might be used after the source has changed.
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SHA1: c0fa0c0e2de50d7eda19ab8862496b18eff93538
User & Date: drh 2014-03-03 17:36:39.940
References
2016-02-08
22:22 • New ticket [d06a25c844] Incorrect result from a UNION with an ORDER BY. (artifact: 4685201918 user: drh)
Context
2014-03-04
04:12
Refactor the sqlite3VdbeRecordCompare() routine used to compare btree records. Create fast-track special case routines to handle the common cases more quickly. This gives a significant performance boost. (check-in: 3325ad5bdc user: drh tags: trunk)
2014-03-03
21:59
Refactor the sqlite3VdbeRecordCompare() routine used to compare btree records. Create a couple of fast-track routines to handle the common cases of a string with BINARY collation or integer values as the left-most column. This gives a significant performance boost in common use. Oops: This build does not work on the Beaglebone where "char" defaults to unsigned. (check-in: aec5473a75 user: drh tags: broken-on-arm)
17:48
Merge latest trunk changes. (check-in: 1d60356462 user: dan tags: experimental)
17:36
Change an OP_SCopy into an OP_Copy in a case where the destination might be used after the source has changed. (check-in: c0fa0c0e2d user: drh tags: trunk)
16:48
Change the "explain_i" tcl test command so that xterm color codes are only added if the output is actually a terminal. (check-in: 559835e54e user: dan tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/select.c.
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      VdbeComment((v, "%s", pEList->a[i].zName));
    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */
    sqlite3ExprCodeExprList(pParse, pEList, regResult,
                            (eDest==SRT_Output)?SQLITE_ECEL_DUP:0);
  }

  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){








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      VdbeComment((v, "%s", pEList->a[i].zName));
    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */
    sqlite3ExprCodeExprList(pParse, pEList, regResult,
                  (eDest==SRT_Output||eDest==SRT_Coroutine)?SQLITE_ECEL_DUP:0);
  }

  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){
︙︙
Added test/selectF.test. 




































































































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# 2014-03-03
#
# 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 verifies that an OP_Copy operation is used instead of OP_SCopy
# in a compound select in a case where the source register might be changed
# before the copy is used.
#

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

do_execsql_test 1 {
  BEGIN TRANSACTION;
  CREATE TABLE t1(a, b, c);
  INSERT INTO "t1" VALUES(1,'one','I');
  CREATE TABLE t2(d, e, f);
  INSERT INTO "t2" VALUES(5,'ten','XX');
  INSERT INTO "t2" VALUES(6,NULL,NULL);

  CREATE INDEX i1 ON t1(b, a);
  COMMIT;
}

#explain_i {
#  SELECT * FROM t2
#  UNION ALL 
#  SELECT * FROM t1 WHERE a<5 
#  ORDER BY 2, 1
#}

do_execsql_test 2 {
  SELECT * FROM t2
  UNION ALL 
  SELECT * FROM t1 WHERE a<5 
  ORDER BY 2, 1
} {6 {} {} 1 one I 5 ten XX}


  
finish_test