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| 1 # 2012 November 9 |
| 2 # |
| 3 # The author disclaims copyright to this source code. In place of |
| 4 # a legal notice, here is a blessing: |
| 5 # |
| 6 # May you do good and not evil. |
| 7 # May you find forgiveness for yourself and forgive others. |
| 8 # May you share freely, never taking more than you give. |
| 9 # |
| 10 #*********************************************************************** |
| 11 # |
| 12 # Test cases for query planning decisions. |
| 13 |
| 14 |
| 15 # |
| 16 # The tests in this file demonstrate the behaviour of the query planner |
| 17 # in determining the order in which joined tables are scanned. |
| 18 # |
| 19 # Assume there are two tables being joined - t1 and t2. Each has a cost |
| 20 # if it is the outer loop, and a cost if it is the inner loop. As follows: |
| 21 # |
| 22 # t1(outer) - cost of scanning t1 as the outer loop. |
| 23 # t1(inner) - cost of scanning t1 as the inner loop. |
| 24 # t2(outer) - cost of scanning t2 as the outer loop. |
| 25 # t2(inner) - cost of scanning t2 as the inner loop. |
| 26 # |
| 27 # Depending on the order in which the planner nests the scans, the total |
| 28 # cost of the join query is one of: |
| 29 # |
| 30 # t1(outer) * t2(inner) |
| 31 # t2(outer) * t1(inner) |
| 32 # |
| 33 # The tests in this file attempt to verify that the planner nests joins in |
| 34 # the correct order when the following are true: |
| 35 # |
| 36 # + (t1(outer) * t2(inner)) > (t1(inner) * t2(outer) |
| 37 # + t1(outer) < t2(outer) |
| 38 # |
| 39 # In other words, when the best overall query plan has t2 as the outer loop, |
| 40 # but when the outer loop is considered independent of the inner, t1 is the |
| 41 # most efficient choice. |
| 42 # |
| 43 # In order to make them more predictable, automatic indexes are turned off for |
| 44 # the tests in this file. |
| 45 # |
| 46 |
| 47 set testdir [file dirname $argv0] |
| 48 source $testdir/tester.tcl |
| 49 set testprefix whereF |
| 50 |
| 51 do_execsql_test 1.0 { |
| 52 PRAGMA automatic_index = 0; |
| 53 CREATE TABLE t1(a, b, c); |
| 54 CREATE TABLE t2(d, e, f); |
| 55 CREATE UNIQUE INDEX i1 ON t1(a); |
| 56 CREATE UNIQUE INDEX i2 ON t2(d); |
| 57 } {} |
| 58 |
| 59 foreach {tn sql} { |
| 60 1 "SELECT * FROM t1, t2 WHERE t1.a=t2.e AND t2.d<t1.b AND t1.c!=10" |
| 61 2 "SELECT * FROM t2, t1 WHERE t1.a=t2.e AND t2.d<t1.b AND t1.c!=10" |
| 62 3 "SELECT * FROM t2 CROSS JOIN t1 WHERE t1.a=t2.e AND t2.d<t1.b AND t1.c!=10" |
| 63 } { |
| 64 do_test 1.$tn { |
| 65 db eval "EXPLAIN QUERY PLAN $sql" |
| 66 } {/.*SCAN TABLE t2\y.*SEARCH TABLE t1\y.*/} |
| 67 } |
| 68 |
| 69 do_execsql_test 2.0 { |
| 70 DROP TABLE t1; |
| 71 DROP TABLE t2; |
| 72 CREATE TABLE t1(a, b, c); |
| 73 CREATE TABLE t2(d, e, f); |
| 74 |
| 75 CREATE UNIQUE INDEX i1 ON t1(a); |
| 76 CREATE UNIQUE INDEX i2 ON t1(b); |
| 77 CREATE UNIQUE INDEX i3 ON t2(d); |
| 78 } {} |
| 79 |
| 80 foreach {tn sql} { |
| 81 1 "SELECT * FROM t1, t2 WHERE t1.a>? AND t2.d>t1.c AND t1.b=t2.e" |
| 82 2 "SELECT * FROM t2, t1 WHERE t1.a>? AND t2.d>t1.c AND t1.b=t2.e" |
| 83 3 "SELECT * FROM t2 CROSS JOIN t1 WHERE t1.a>? AND t2.d>t1.c AND t1.b=t2.e" |
| 84 } { |
| 85 do_test 2.$tn { |
| 86 db eval "EXPLAIN QUERY PLAN $sql" |
| 87 } {/.*SCAN TABLE t2\y.*SEARCH TABLE t1\y.*/} |
| 88 } |
| 89 |
| 90 do_execsql_test 3.0 { |
| 91 DROP TABLE t1; |
| 92 DROP TABLE t2; |
| 93 CREATE TABLE t1(a, b, c); |
| 94 CREATE TABLE t2(d, e, f); |
| 95 |
| 96 CREATE UNIQUE INDEX i1 ON t1(a, b); |
| 97 CREATE INDEX i2 ON t2(d); |
| 98 } {} |
| 99 |
| 100 foreach {tn sql} { |
| 101 1 {SELECT t1.a, t1.b, t2.d, t2.e FROM t1, t2 |
| 102 WHERE t2.d=t1.b AND t1.a=(t2.d+1) AND t1.b = (t2.e+1)} |
| 103 |
| 104 2 {SELECT t1.a, t1.b, t2.d, t2.e FROM t2, t1 |
| 105 WHERE t2.d=t1.b AND t1.a=(t2.d+1) AND t1.b = (t2.e+1)} |
| 106 |
| 107 3 {SELECT t1.a, t1.b, t2.d, t2.e FROM t2 CROSS JOIN t1 |
| 108 WHERE t2.d=t1.b AND t1.a=(t2.d+1) AND t1.b = (t2.e+1)} |
| 109 } { |
| 110 do_test 3.$tn { |
| 111 db eval "EXPLAIN QUERY PLAN $sql" |
| 112 } {/.*SCAN TABLE t2\y.*SEARCH TABLE t1\y.*/} |
| 113 } |
| 114 |
| 115 do_execsql_test 4.0 { |
| 116 CREATE TABLE t4(a,b,c,d,e, PRIMARY KEY(a,b,c)); |
| 117 CREATE INDEX t4adc ON t4(a,d,c); |
| 118 CREATE UNIQUE INDEX t4aebc ON t4(a,e,b,c); |
| 119 EXPLAIN QUERY PLAN SELECT rowid FROM t4 WHERE a=? AND b=?; |
| 120 } {/a=. AND b=./} |
| 121 |
| 122 finish_test |
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