782d68a4cd
of a join to use for the outer loop. FossilOrigin-Name: 942556342a332b04a11169bb04f387d741ef9488
116 lines
3.4 KiB
Plaintext
116 lines
3.4 KiB
Plaintext
# 2012 November 9
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#
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# The author disclaims copyright to this source code. In place of
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# a legal notice, here is a blessing:
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#
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# May you do good and not evil.
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# May you find forgiveness for yourself and forgive others.
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# May you share freely, never taking more than you give.
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#
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#***********************************************************************
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#
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# Test cases for query planning decisions.
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#
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# The tests in this file demonstrate the behaviour of the query planner
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# in determining the order in which joined tables are scanned.
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#
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# Assume there are two tables being joined - t1 and t2. Each has a cost
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# if it is the outer loop, and a cost if it is the inner loop. As follows:
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#
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# t1(outer) - cost of scanning t1 as the outer loop.
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# t1(inner) - cost of scanning t1 as the inner loop.
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# t2(outer) - cost of scanning t2 as the outer loop.
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# t2(inner) - cost of scanning t2 as the inner loop.
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#
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# Depending on the order in which the planner nests the scans, the total
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# cost of the join query is one of:
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#
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# t1(outer) * t2(inner)
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# t2(outer) * t1(inner)
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#
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# The tests in this file attempt to verify that the planner nests joins in
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# the correct order when the following are true:
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#
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# + (t1(outer) * t2(inner)) > (t1(inner) * t2(outer)
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# + t1(outer) < t2(outer)
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#
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# In other words, when the best overall query plan has t2 as the outer loop,
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# but when the outer loop is considered independent of the inner, t1 is the
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# most efficient choice.
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#
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# In order to make them more predictable, automatic indexes are turned off for
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# the tests in this file.
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#
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set testdir [file dirname $argv0]
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source $testdir/tester.tcl
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set testprefix x
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do_execsql_test 1.0 {
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PRAGMA automatic_index = 0;
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CREATE TABLE t1(a, b, c);
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CREATE TABLE t2(d, e, f);
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CREATE UNIQUE INDEX i1 ON t1(a);
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CREATE UNIQUE INDEX i2 ON t2(d);
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} {}
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foreach {tn sql} {
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1 "SELECT * FROM t1, t2 WHERE t1.a=t2.e AND t2.d<t1.b AND t1.c!=10"
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2 "SELECT * FROM t2, t1 WHERE t1.a=t2.e AND t2.d<t1.b AND t1.c!=10"
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3 "SELECT * FROM t2 CROSS JOIN t1 WHERE t1.a=t2.e AND t2.d<t1.b AND t1.c!=10"
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} {
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do_test 1.$tn {
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db eval "EXPLAIN QUERY PLAN $sql"
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} {/.*SCAN TABLE t2 .*SEARCH TABLE t1 .*/}
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}
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do_execsql_test 2.0 {
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DROP TABLE t1;
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DROP TABLE t2;
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CREATE TABLE t1(a, b, c);
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CREATE TABLE t2(d, e, f);
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CREATE UNIQUE INDEX i1 ON t1(a);
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CREATE UNIQUE INDEX i2 ON t1(b);
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CREATE UNIQUE INDEX i3 ON t2(d);
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} {}
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foreach {tn sql} {
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1 "SELECT * FROM t1, t2 WHERE t1.a>? AND t2.d>t1.c AND t1.b=t2.e"
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2 "SELECT * FROM t2, t1 WHERE t1.a>? AND t2.d>t1.c AND t1.b=t2.e"
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3 "SELECT * FROM t2 CROSS JOIN t1 WHERE t1.a>? AND t2.d>t1.c AND t1.b=t2.e"
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} {
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do_test 2.$tn {
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db eval "EXPLAIN QUERY PLAN $sql"
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} {/.*SCAN TABLE t2 .*SEARCH TABLE t1 .*/}
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}
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do_execsql_test 3.0 {
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DROP TABLE t1;
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DROP TABLE t2;
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CREATE TABLE t1(a, b, c);
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CREATE TABLE t2(d, e, f);
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CREATE UNIQUE INDEX i1 ON t1(a, b);
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CREATE INDEX i2 ON t2(d);
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} {}
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foreach {tn sql} {
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1 {SELECT t1.a, t1.b, t2.d, t2.e FROM t1, t2
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WHERE t2.d=t1.b AND t1.a=(t2.d+1) AND t1.b = (t2.e+1)}
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2 {SELECT t1.a, t1.b, t2.d, t2.e FROM t2, t1
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WHERE t2.d=t1.b AND t1.a=(t2.d+1) AND t1.b = (t2.e+1)}
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3 {SELECT t1.a, t1.b, t2.d, t2.e FROM t2 CROSS JOIN t1
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WHERE t2.d=t1.b AND t1.a=(t2.d+1) AND t1.b = (t2.e+1)}
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} {
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do_test 3.$tn {
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db eval "EXPLAIN QUERY PLAN $sql"
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} {/.*SCAN TABLE t2 .*SEARCH TABLE t1 .*/}
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}
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finish_test
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