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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Artifact 67817a4b6857c47e0e33ba3e506da6f23ef68de2:


# 2013-11-13
#
# 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 tests of the "skip-scan" query strategy. In 
# particular it tests that stat4 data can be used by a range query
# that uses the skip-scan approach.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix skipscan5

ifcapable !stat4 {
  finish_test
  return
}

do_execsql_test 1.1 {
  CREATE TABLE t1(a INT, b INT, c INT);
  CREATE INDEX i1 ON t1(a, b);
} {}

expr srand(4)
do_test 1.2 {
  for {set i 0} {$i < 100} {incr i} {
    set a [expr int(rand()*4.0) + 1]
    set b [expr int(rand()*20.0) + 1]
    execsql { INSERT INTO t1 VALUES($a, $b, NULL) }
  }
  execsql ANALYZE
} {}

foreach {tn q res} {
  1  "b = 5"                   {/*ANY(a) AND b=?*/}
  2  "b > 12 AND b < 16"       {/*ANY(a) AND b>? AND b<?*/}
  3  "b > 2 AND b < 16"        {/*SCAN TABLE t1*/}
  4  "b > 18 AND b < 25"       {/*ANY(a) AND b>? AND b<?*/}
  5  "b > 15"                  {/*ANY(a) AND b>?*/}
  6  "b > 5"                   {/*SCAN TABLE t1*/}
  7  "b < 15"                  {/*SCAN TABLE t1*/}
  8  "b < 5"                   {/*ANY(a) AND b<?*/}
  9  "5 > b"                   {/*ANY(a) AND b<?*/}
  10 "b = '5'"                 {/*ANY(a) AND b=?*/}
  11 "b > '12' AND b < '16'"   {/*ANY(a) AND b>? AND b<?*/}
  12 "b > '2' AND b < '16'"    {/*SCAN TABLE t1*/}
  13 "b > '18' AND b < '25'"   {/*ANY(a) AND b>? AND b<?*/}
  14 "b > '15'"                {/*ANY(a) AND b>?*/}
  15 "b > '5'"                 {/*SCAN TABLE t1*/}
  16 "b < '15'"                {/*SCAN TABLE t1*/}
  17 "b < '5'"                 {/*ANY(a) AND b<?*/}
  18 "'5' > b"                 {/*ANY(a) AND b<?*/}
} {
  set sql "EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE $q"
  do_execsql_test 1.3.$tn $sql $res
}


#-------------------------------------------------------------------------
# Test that range-query/skip-scan estimation works with text values.
# And on UTF-16 databases when there is no UTF-16 collation sequence
# available.
#

proc test_collate {enc lhs rhs} {
  string compare $lhs $rhs
}

foreach {tn dbenc coll} {
  1 UTF-8   { add_test_collate db 0 0 1 }
  2 UTF-16  { add_test_collate db 1 0 0 }
  3 UTF-8   { add_test_collate db 0 1 0 }
} {
  reset_db
  eval $coll

  do_execsql_test 2.$tn.1 " PRAGMA encoding = '$dbenc' "
  do_execsql_test 2.$tn.2 {
    CREATE TABLE t2(a TEXT, b TEXT, c TEXT COLLATE test_collate, d TEXT);
    CREATE INDEX i2 ON t2(a, b, c);
  }

  set vocab(d) { :) }
  set vocab(c) { a b c d e f g h i j k l m n o p q r s t }
  set vocab(b) { one two three }
  set vocab(a) { sql }

  do_test 2.$tn.3 {
    for {set i 0} {$i < 100} {incr i} {
      foreach var {a b c d} { 
        set $var [lindex $vocab($var) [expr $i % [llength $vocab($var)]]]
      }
      execsql { INSERT INTO t2 VALUES($a, $b, $c, $d) }
    }
    execsql ANALYZE
  } {}

  foreach {tn2 q res} {
    1 { c BETWEEN 'd' AND 'e' }       {/*ANY(a) AND ANY(b) AND c>? AND c<?*/}
    2 { c BETWEEN 'b' AND 'r' }       {/*SCAN TABLE t2*/}
    3 { c > 'q' }                     {/*ANY(a) AND ANY(b) AND c>?*/}
    4 { c > 'e' }                     {/*SCAN TABLE t2*/}
    5 { c < 'q' }                     {/*SCAN TABLE t2*/}
    6 { c < 'c' }                     {/*ANY(a) AND ANY(b) AND c<?*/}
  } {
    set sql "EXPLAIN QUERY PLAN SELECT * FROM t2 WHERE $q" 
    do_execsql_test 2.$tn.$tn2 $sql $res
  }

}

#-------------------------------------------------------------------------
# Test that range-query/skip-scan estimation works on columns that contain
# a variety of types.
#

reset_db
do_execsql_test 3.1 {
  CREATE TABLE t3(a, b, c);
  CREATE INDEX i3 ON t3(a, b);
}

set values {
    NULL NULL NULL
    NULL -9567 -9240
    -8725 -8659 -8248.340244520614
    -8208 -7939 -7746.985758536954
    -7057 -6550 -5916
    -5363 -4935.781822975623 -4935.063633571875
    -3518.4554911770183 -2537 -2026
    -1511.2603881914456 -1510.4195994839156 -1435
    -1127.4210136045804 -1045 99
    1353 1457 1563.2908193223611
    2245 2286 2552
    2745.18831295203 2866.279926554429 3075.0468527316334
    3447 3867 4237.892420141907
    4335 5052.9775000424015 5232.178240656935
    5541.784919585003 5749.725576373621 5758
    6005 6431 7263.477992854769
    7441 7541 8667.279760663994
    8857 9199.638673662972 'dl'
    'dro' 'h' 'igprfq'
    'jnbd' 'k' 'kordee'
    'lhwcv' 'mzlb' 'nbjked'
    'nufpo' 'nxqkdq' 'shelln'
    'tvzn' 'wpnt' 'wylf'
    'ydkgu' 'zdb' X''
    X'0a' X'203f6429f1f33f' X'23858e324545e0362b'
    X'3f9f8a' X'516f7ddd4b' X'68f1df0930ac6b'
    X'9ea60d' X'a06f' X'aefd342a39ce36df'
    X'afaa020fe2' X'be201c' X'c47d97b209601e45'
}

do_test 3.2 {
  set c 0
  foreach v $values {
    execsql "INSERT INTO t3 VALUES($c % 2, $v, $c)"
    incr c
  }
  execsql ANALYZE
} {}

foreach {tn q res} {
  1 "b BETWEEN -10000 AND -8000"       {/*ANY(a) AND b>? AND b<?*/}
  2 "b BETWEEN -10000 AND 'qqq'"       {/*SCAN TABLE t3*/}
  3 "b < X'5555'"                      {/*SCAN TABLE t3*/}
  4 "b > X'5555'"                      {/*ANY(a) AND b>?*/}
  5 "b > 'zzz'"                        {/*ANY(a) AND b>?*/}
  6 "b < 'zzz'"                        {/*SCAN TABLE t3*/}
} {
  set sql "EXPLAIN QUERY PLAN SELECT * FROM t3 WHERE $q" 
  do_execsql_test 3.3.$tn $sql $res
}

finish_test