sqlite/test/limit2.test

# 2016-05-20
#
# 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 the LIMIT in combination with ORDER BY
# and in particular, the optimizations in the inner loop that cause an
# early exit of the inner loop when the LIMIT is reached and the inner
# loop is emitting rows in ORDER BY order.


set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix limit2

do_execsql_test limit2-100 {
  CREATE TABLE t1(a,b);
  WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<1000)
    INSERT INTO t1(a,b) SELECT 1, (x*17)%1000 + 1000 FROM c;
  INSERT INTO t1(a,b) VALUES(2,2),(3,1006),(4,4),(5,9999);
  CREATE INDEX t1ab ON t1(a,b);
}
set sqlite_search_count 0
do_execsql_test limit2-100.1 {
  SELECT a, b, '|' FROM t1 WHERE a IN (2,4,5,3,1) ORDER BY b LIMIT 5;
} {2 2 | 4 4 | 1 1000 | 1 1001 | 1 1002 |}
set fast_count $sqlite_search_count
set sqlite_search_count 0
do_execsql_test limit2-100.2 {
  SELECT a, b, '|' FROM t1 WHERE a IN (2,4,5,3,1) ORDER BY +b LIMIT 5;
} {2 2 | 4 4 | 1 1000 | 1 1001 | 1 1002 |}
do_test limit2-100.3 {
  set slow_count $sqlite_search_count
  expr {$fast_count < 0.02*$slow_count}
} {1}

do_execsql_test limit2-110 {
  CREATE TABLE t2(x,y);
  INSERT INTO t2(x,y) VALUES('a',1),('a',2),('a',3),('a',4);
  INSERT INTO t2(x,y) VALUES('b',1),('c',2),('d',3),('e',4);
  CREATE INDEX t2xy ON t2(x,y);
}
set sqlite_search_count 0
do_execsql_test limit2-110.1 {
  SELECT a, b, '|' FROM t2, t1 WHERE t2.x='a' AND t1.a=t2.y ORDER BY t1.b LIMIT 5;
} {2 2 | 4 4 | 1 1000 | 1 1001 | 1 1002 |}
set fast_count $sqlite_search_count
set sqlite_search_count 0
do_execsql_test limit2-110.2 {
  SELECT a, b, '|' FROM t2, t1 WHERE t2.x='a' AND t1.a=t2.y ORDER BY +t1.b LIMIT 5;
} {2 2 | 4 4 | 1 1000 | 1 1001 | 1 1002 |}
set slow_count $sqlite_search_count
do_test limit2-110.3 {
  expr {$fast_count < 0.02*$slow_count}
} {1}

do_execsql_test limit2-120 {
  DROP INDEX t1ab;
  CREATE INDEX t1ab ON t1(a,b DESC);
}
set sqlite_search_count 0
do_execsql_test limit2-120.1 {
  SELECT a, b, '|' FROM t1 WHERE a IN (2,4,5,3,1) ORDER BY b DESC LIMIT 5;
} {5 9999 | 1 1999 | 1 1998 | 1 1997 | 1 1996 |}
set fast_count $sqlite_search_count
set sqlite_search_count 0
do_execsql_test limit2-120.2 {
  SELECT a, b, '|' FROM t1 WHERE a IN (2,4,5,3,1) ORDER BY +b DESC LIMIT 5;
} {5 9999 | 1 1999 | 1 1998 | 1 1997 | 1 1996 |}
do_test limit2-120.3 {
  set slow_count $sqlite_search_count
  expr {$fast_count < 0.02*$slow_count}
} {1}

# Bug report against the new ORDER BY LIMIT optimization just prior to
# release.  (Unreleased so there is no ticket).
#
# Make sure the optimization is not applied if the inner loop can only
# provide a single row of output.
#
do_execsql_test limit2-200 {
  CREATE TABLE t200(a, b);
  WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<1000)
    INSERT INTO t200(a,b) SELECT x, x FROM c;
  CREATE TABLE t201(x INTEGER PRIMARY KEY, y);
  INSERT INTO t201(x,y) VALUES(2,12345);

  SELECT *, '|' FROM t200, t201 WHERE x=b ORDER BY y LIMIT 3;
} {2 2 2 12345 |}
do_execsql_test limit2-210 {
  SELECT *, '|' FROM t200 LEFT JOIN t201 ON x=b ORDER BY y LIMIT 3;
} {1 1 {} {} | 3 3 {} {} | 4 4 {} {} |}

# Bug in the ORDER BY LIMIT optimization reported on 2016-09-06.
# Ticket https://www.sqlite.org/src/info/559733b09e96
#
do_execsql_test limit2-300 {
  CREATE TABLE t300(a,b,c);
  CREATE INDEX t300x ON t300(a,b,c);
  INSERT INTO t300 VALUES(0,1,99),(0,1,0),(0,0,0);
  SELECT *,'.' FROM t300 WHERE a=0 AND (c=0 OR c=99) ORDER BY c DESC;
} {0 1 99 . 0 0 0 . 0 1 0 .}
do_execsql_test limit2-310 {
  SELECT *,'.' FROM t300 WHERE a=0 AND (c=0 OR c=99) ORDER BY c DESC LIMIT 1;
} {0 1 99 .}

# Make sure the SELECT loop is ordered correctly for the direction of
# the ORDER BY
#
do_execsql_test limit2-400 {
  CREATE TABLE t400(a,b);
  CREATE INDEX t400_ab ON t400(a,b);
  INSERT INTO t400(a,b) VALUES(1,90),(1,40),(2,80),(2,30),(3,70),(3,20);
  SELECT *,'x' FROM t400 WHERE a IN (1,2,3) ORDER BY b DESC LIMIT 3;
  SELECT *,'y' FROM t400 WHERE a IN (1,2,3) ORDER BY +b DESC LIMIT 3;
} {1 90 x 2 80 x 3 70 x 1 90 y 2 80 y 3 70 y}


do_execsql_test 500 {
  CREATE TABLE t500(i INTEGER PRIMARY KEY, j);
  INSERT INTO t500 VALUES(1, 1);
  INSERT INTO t500 VALUES(2, 2);
  INSERT INTO t500 VALUES(3, 3);
  INSERT INTO t500 VALUES(4, 0);
  INSERT INTO t500 VALUES(5, 5);
  SELECT j FROM t500 WHERE i IN (1,2,3,4,5) ORDER BY j DESC LIMIT 3;
} {5 3 2}
do_execsql_test 501 {
  CREATE TABLE t501(i INTEGER PRIMARY KEY, j);
  INSERT INTO t501 VALUES(1, 5);
  INSERT INTO t501 VALUES(2, 4);
  INSERT INTO t501 VALUES(3, 3);
  INSERT INTO t501 VALUES(4, 6);
  INSERT INTO t501 VALUES(5, 1);
  SELECT j FROM t501 WHERE i IN (1,2,3,4,5) ORDER BY j LIMIT 3;
} {1 3 4}
do_execsql_test 502 {
  CREATE TABLE t502(i INT PRIMARY KEY, j);
  INSERT INTO t502 VALUES(1, 5);
  INSERT INTO t502 VALUES(2, 4);
  INSERT INTO t502 VALUES(3, 3);
  INSERT INTO t502 VALUES(4, 6);
  INSERT INTO t502 VALUES(5, 1);
  SELECT j FROM t502 WHERE i IN (1,2,3,4,5) ORDER BY j LIMIT 3;
} {1 3 4}

# Ticket https://www.sqlite.org/src/info/123c9ba32130a6c9 2017-12-13
# Incorrect result when an idnex is used for an ordered join.
#
# This test case is in the limit2.test module because the problem was first
# exposed by check-in https://www.sqlite.org/src/info/559733b09e which 
# implemented the ORDER BY LIMIT optimization that limit2.test strives to
# test.
#
do_execsql_test 600 {
  DROP TABLE IF EXISTS t1;
  CREATE TABLE t1(a, b);  INSERT INTO t1 VALUES(1,2);
  DROP TABLE IF EXISTS t2;
  CREATE TABLE t2(x, y);  INSERT INTO t2 VALUES(1,3);
  CREATE INDEX t1ab ON t1(a,b);
  SELECT y FROM t1, t2 WHERE a=x AND b<=y ORDER BY b DESC;
} {3}

finish_test