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

Artifact 852170bddbb21daa121fabcc274640ff83d7d8705912e8b5fe7ed2c5a9a9224a:


# 2016-03-01
#
# 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.
#
#***********************************************************************
# 
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix bestindex1

ifcapable !vtab {
  finish_test
  return
}

register_tcl_module db

proc vtab_command {method args} {
  switch -- $method {
    xConnect {
      return "CREATE TABLE t1(a, b, c)"
    }

    xBestIndex {
      set clist [lindex $args 0]
      if {[llength $clist]!=1} { error "unexpected constraint list" }
      catch { array unset C }
      array set C [lindex $clist 0]
      if {$C(usable)} {
        return "omit 0 cost 0 rows 1 idxnum 555 idxstr eq!"
      } else {
        return "cost 1000000 rows 0 idxnum 0 idxstr scan..."
      }
    }

  }

  return {}
}

do_execsql_test 1.0 {
  CREATE VIRTUAL TABLE x1 USING tcl(vtab_command);
} {}

do_eqp_test 1.1 {
  SELECT * FROM x1 WHERE a = 'abc'
} {SCAN TABLE x1 VIRTUAL TABLE INDEX 555:eq!}

do_eqp_test 1.2 {
  SELECT * FROM x1 WHERE a IN ('abc', 'def');
} {SCAN TABLE x1 VIRTUAL TABLE INDEX 555:eq!}

#-------------------------------------------------------------------------
#
reset_db
register_tcl_module db

# Parameter $mode may be one of:
#
#   "omit" - Implement filtering. Set the omit flag.
#   "use"  - Implement filtering. Use the constraint, but do not set omit.
#   "use2" - Do not implement filtering. Use the constraint anyway.
#
#   
proc t1_vtab {mode method args} {
  switch -- $method {
    xConnect {
      return "CREATE TABLE t1(a, b)"
    }

    xBestIndex {
      set SQL_FILTER {SELECT * FROM t1x WHERE a='%1%'}
      set SQL_SCAN   {SELECT * FROM t1x}

      set clist [lindex $args 0]
      set idx 0
      for {set idx 0} {$idx < [llength $clist]} {incr idx} {
        array unset C
        array set C [lindex $clist $idx]
        if {$C(column)==0 && $C(op)=="eq" && $C(usable)} {
          switch -- $mode {
            "omit" {
              return [list omit $idx rows 10 cost 10 idxstr $SQL_FILTER]
            }
            "use" {
              return [list use $idx rows 10 cost 10 idxstr $SQL_FILTER]
            }
            "use2" {
              return [list use $idx rows 10 cost 10 idxstr $SQL_SCAN]
            }
            default {
              error "Bad mode - $mode"
            }
          }
        }
      }

      return [list idxstr {SELECT * FROM t1x}]
    }

    xFilter {
      set map [list %1% [lindex $args 2 0]]
      set sql [string map $map [lindex $args 1]]
      return [list sql $sql]
    }
  }

  return {}
}

do_execsql_test 2.1 {
  CREATE TABLE t1x(i INTEGER PRIMARY KEY, a, b);
  INSERT INTO t1x VALUES(1, 'one', 1);
  INSERT INTO t1x VALUES(2, 'two', 2);
  INSERT INTO t1x VALUES(3, 'three', 3);
  INSERT INTO t1x VALUES(4, 'four', 4);
}

foreach {tn mode} {
  1 use 2 omit 3 use2
} {
  do_execsql_test 2.2.$mode.1 "
    DROP TABLE IF EXISTS t1;
    CREATE VIRTUAL TABLE t1 USING tcl(t1_vtab $mode);
  "

  do_execsql_test 2.2.$mode.2 {SELECT * FROM t1} {one 1 two 2 three 3 four 4}
  do_execsql_test 2.2.$mode.3 {SELECT rowid FROM t1} {1 2 3 4}
  do_execsql_test 2.2.$mode.4 {SELECT rowid FROM t1 WHERE a='two'} {2} 

  do_execsql_test 2.2.$mode.5 {
    SELECT rowid FROM t1 WHERE a IN ('one', 'four') ORDER BY +rowid
  } {1 4} 

  set plan(use) {
    QUERY PLAN
    |--SCAN TABLE t1 VIRTUAL TABLE INDEX 0:SELECT * FROM t1x WHERE a='%1%'
    `--USE TEMP B-TREE FOR ORDER BY
  }
  set plan(omit) {
    QUERY PLAN
    |--SCAN TABLE t1 VIRTUAL TABLE INDEX 0:SELECT * FROM t1x WHERE a='%1%'
    `--USE TEMP B-TREE FOR ORDER BY
  }
  set plan(use2) {
    QUERY PLAN
    |--SCAN TABLE t1 VIRTUAL TABLE INDEX 0:SELECT * FROM t1x
    `--USE TEMP B-TREE FOR ORDER BY
  }

  do_eqp_test 2.2.$mode.6 { 
    SELECT rowid FROM t1 WHERE a IN ('one', 'four') ORDER BY +rowid
  } [string map {"\n  " "\n"} $plan($mode)]
}

# 2016-04-09.
# Demonstrate a register overwrite problem when using two virtual
# tables where the outer loop uses the IN operator.
#
set G(collist) [list PrimaryKey flagA columnA]
set G(cols) [join $G(collist) ,]
set G(nulls) "NULL"

proc vtab_command {method args} {
  global G

  switch -- $method {
    xConnect {
      return "CREATE TABLE t1($G(cols))"
    }

    xBestIndex {
      set clist [lindex $args 0]
      #puts $clist
      set W [list]
      set U [list]

      set i 0
      for {set idx 0} {$idx < [llength $clist]} {incr idx} {
        array set c [lindex $clist $idx]
        if {$c(op)=="eq" && $c(usable)} {
          lappend W "[lindex $G(collist) $c(column)] = %$i%"
          lappend U use $idx
          incr i
        }
      }

      if {$W==""} {
        set sql "SELECT rowid, * FROM t1"
      } else {
        set sql "SELECT rowid, * FROM t1 WHERE [join $W { AND }]"
      }

      return [concat [list idxstr $sql] $U]
    }

    xFilter {
      foreach {idxnum idxstr vals} $args {}

      set map [list]
      for {set i 0} {$i < [llength $vals]} {incr i} {
        lappend map "%$i%" 
        set v [lindex $vals $i]
        if {[string is integer $v]} { 
          lappend map $v 
        } else {
          lappend map "'$v'"
        }
      }
      set sql [string map $map $idxstr]

      #puts "SQL: $sql"
      return [list sql $sql]
    }
  }

  return {}
}

db close
forcedelete test.db
sqlite3 db test.db
register_tcl_module db

do_execsql_test 3.1 "
  CREATE TABLE t1($G(cols));
  INSERT INTO t1 VALUES(1, 0, 'ValueA');
  INSERT INTO t1 VALUES(2, 0, 'ValueA');
  INSERT INTO t1 VALUES(3, 0, 'ValueB');
  INSERT INTO t1 VALUES(4, 0, 'ValueB');
"

do_execsql_test 3.2 {
  CREATE VIRTUAL TABLE VirtualTableA USING tcl(vtab_command);
  CREATE VIRTUAL TABLE VirtualTableB USING tcl(vtab_command);
}

do_execsql_test 3.3 { SELECT primarykey FROM VirtualTableA } {1 2 3 4}

do_execsql_test 3.4 {
  SELECT * FROM 
  VirtualTableA a CROSS JOIN VirtualTableB b ON b.PrimaryKey=a.PrimaryKey
  WHERE a.ColumnA IN ('ValueA', 'ValueB') AND a.FlagA=0
} {
  1 0 ValueA 1 0 ValueA
  2 0 ValueA 2 0 ValueA
  3 0 ValueB 3 0 ValueB
  4 0 ValueB 4 0 ValueB
}

do_execsql_test 3.5 {
  SELECT * FROM 
  VirtualTableA a CROSS JOIN VirtualTableB b ON b.PrimaryKey=a.PrimaryKey
  WHERE a.FlagA=0 AND a.ColumnA IN ('ValueA', 'ValueB') 
} {
  1 0 ValueA 1 0 ValueA
  2 0 ValueA 2 0 ValueA
  3 0 ValueB 3 0 ValueB
  4 0 ValueB 4 0 ValueB
}


finish_test