1# 2020-02-23 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# Tests for functionality related to ANALYZE. 12# 13 14set testdir [file dirname $argv0] 15source $testdir/tester.tcl 16 17ifcapable !stat4 { 18 finish_test 19 return 20} 21set testprefix analyzeG 22 23#------------------------------------------------------------------------- 24# Test cases 1.* seek to verify that even if an index is not used, its 25# stat4 data may be used by the planner to estimate the number of 26# rows that match an unindexed constraint on the same column. 27# 28do_execsql_test 1.0 { 29 PRAGMA automatic_index = 0; 30 CREATE TABLE t1(a, x); 31 CREATE TABLE t2(b, y); 32 WITH s(i) AS ( 33 SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100 34 ) 35 INSERT INTO t1 SELECT (i%50), NULL FROM s; 36 WITH s(i) AS ( 37 SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<100 38 ) 39 INSERT INTO t2 SELECT (CASE WHEN i<95 THEN 44 ELSE i END), NULL FROM s; 40} 41 42# Join tables t1 and t2. Both contain 100 rows. (a=44) matches 2 rows 43# in "t1", (b=44) matches 95 rows in table "t2". But the planner doesn't 44# know this, so it has no preference as to which order the tables are 45# scanned in. In practice this means that tables are scanned in the order 46# they are specified in in the FROM clause. 47do_eqp_test 1.1.1 { 48 SELECT * FROM t1, t2 WHERE a=44 AND b=44; 49} { 50 51} 52do_eqp_test 1.1.2 { 53 SELECT * FROM t2, t1 WHERE a=44 AND b=44 54} { 55 QUERY PLAN 56 |--SCAN t2 57 `--SCAN t1 58} 59 60do_execsql_test 1.2 { 61 CREATE INDEX t2b ON t2(b); 62 ANALYZE; 63} 64 65# Now, with the ANALYZE data, the planner knows that (b=44) matches a 66# large number of rows. So it elects to scan table "t1" first, regardless 67# of the order in which the tables are specified in the FROM clause. 68do_eqp_test 1.3.1 { 69 SELECT * FROM t1, t2 WHERE a=44 AND b=44; 70} { 71 QUERY PLAN 72 |--SCAN t1 73 `--SCAN t2 74} 75do_eqp_test 1.3.2 { 76 SELECT * FROM t2, t1 WHERE a=44 AND b=44 77} { 78 QUERY PLAN 79 |--SCAN t1 80 `--SCAN t2 81} 82 83 84finish_test 85