gitlab.com/CoiaPrant/sqlite3@v1.19.1/testdata/tcl/analyze8.test (about)

     1  # 2011 August 13
     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  # This file implements tests for SQLite library.  The focus of the tests
    13  # in this file is testing the capabilities of sqlite_stat4.
    14  #
    15  
    16  set testdir [file dirname $argv0]
    17  source $testdir/tester.tcl
    18  
    19  ifcapable !stat4 {
    20    finish_test
    21    return
    22  }
    23  
    24  set testprefix analyze8
    25  
    26  proc eqp {sql {db db}} {
    27    uplevel execsql [list "EXPLAIN QUERY PLAN $sql"] $db
    28  }
    29  
    30  # Scenario:
    31  #
    32  #    Two indices.  One has mostly singleton entries, but for a few
    33  #    values there are hundreds of entries.  The other has 10-20
    34  #    entries per value.
    35  #
    36  # Verify that the query planner chooses the first index for the singleton
    37  # entries and the second index for the others.
    38  #
    39  do_test 1.0 {
    40    db eval {
    41      CREATE TABLE t1(a,b,c,d);
    42      CREATE INDEX t1a ON t1(a);
    43      CREATE INDEX t1b ON t1(b);
    44      CREATE INDEX t1c ON t1(c);
    45    }
    46    for {set i 0} {$i<1000} {incr i} {
    47      if {$i%2==0} {set a $i} {set a [expr {($i%8)*100}]}
    48      set b [expr {$i/10}]
    49      set c [expr {$i/8}]
    50      set c [expr {$c*$c*$c}]
    51      db eval {INSERT INTO t1 VALUES($a,$b,$c,$i)}
    52    }
    53    db eval {ANALYZE}
    54  } {}
    55  
    56  # The a==100 comparison is expensive because there are many rows
    57  # with a==100.  And so for those cases, choose the t1b index.
    58  #
    59  # Buf ro a==99 and a==101, there are far fewer rows so choose
    60  # the t1a index.
    61  #
    62  do_test 1.1 {
    63    eqp {SELECT * FROM t1 WHERE a=100 AND b=55}
    64  } {/*SEARCH t1 USING INDEX t1b (b=?)*/}
    65  do_test 1.2 {
    66    eqp {SELECT * FROM t1 WHERE a=99 AND b=55}
    67  } {/*SEARCH t1 USING INDEX t1a (a=?)*/}
    68  do_test 1.3 {
    69    eqp {SELECT * FROM t1 WHERE a=101 AND b=55}
    70  } {/*SEARCH t1 USING INDEX t1a (a=?)*/}
    71  do_test 1.4 {
    72    eqp {SELECT * FROM t1 WHERE a=100 AND b=56}
    73  } {/*SEARCH t1 USING INDEX t1b (b=?)*/}
    74  do_test 1.5 {
    75    eqp {SELECT * FROM t1 WHERE a=99 AND b=56}
    76  } {/*SEARCH t1 USING INDEX t1a (a=?)*/}
    77  do_test 1.6 {
    78    eqp {SELECT * FROM t1 WHERE a=101 AND b=56}
    79  } {/*SEARCH t1 USING INDEX t1a (a=?)*/}
    80  do_test 2.1 {
    81    eqp {SELECT * FROM t1 WHERE a=100 AND b BETWEEN 50 AND 54}
    82  } {/*SEARCH t1 USING INDEX t1b (b>? AND b<?)*/}
    83  
    84  # There are many more values of c between 0 and 100000 than there are
    85  # between 800000 and 900000.  So t1c is more selective for the latter
    86  # range.
    87  # 
    88  # Test 3.2 is a little unstable. It depends on the planner estimating
    89  # that (b BETWEEN 30 AND 34) will match more rows than (c BETWEEN
    90  # 800000 AND 900000). Which is a pretty close call (50 vs. 32), so
    91  # the planner could get it wrong with an unlucky set of samples. This
    92  # case happens to work, but others ("b BETWEEN 40 AND 44" for example) 
    93  # will fail.
    94  #
    95  do_execsql_test 3.0 {
    96    SELECT count(*) FROM t1 WHERE b BETWEEN 30 AND 34;
    97    SELECT count(*) FROM t1 WHERE c BETWEEN 0 AND 100000;
    98    SELECT count(*) FROM t1 WHERE c BETWEEN 800000 AND 900000;
    99  } {50 376 32}
   100  do_test 3.1 {
   101    eqp {SELECT * FROM t1 WHERE b BETWEEN 30 AND 34 AND c BETWEEN 0 AND 100000}
   102  } {/*SEARCH t1 USING INDEX t1b (b>? AND b<?)*/}
   103  do_test 3.2 {
   104    eqp {SELECT * FROM t1
   105         WHERE b BETWEEN 30 AND 34 AND c BETWEEN 800000 AND 900000}
   106  } {/*SEARCH t1 USING INDEX t1c (c>? AND c<?)*/}
   107  do_test 3.3 {
   108    eqp {SELECT * FROM t1 WHERE a=100 AND c BETWEEN 0 AND 100000}
   109  } {/*SEARCH t1 USING INDEX t1a (a=?)*/}
   110  do_test 3.4 {
   111    eqp {SELECT * FROM t1
   112         WHERE a=100 AND c BETWEEN 800000 AND 900000}
   113  } {/*SEARCH t1 USING INDEX t1c (c>? AND c<?)*/}
   114  
   115  finish_test