/ Artifact [40e79f3d]

## Artifact 40e79f3d95f2077742aa5b7676f58c9af1735d83:

• File test/limit2.test — part of check-in [13e3bd3d] at 2016-08-04 09:09:44 on branch trunk — Make sure the ORDER BY LIMIT optimization is not applied if the inner-most loop can only have a single iteration and is hence not really a loop. (user: drh size: 3554) [more...]

``````# 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

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 {} {} |}

finish_test
```
```