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

Artifact 4cb5ff7dbaebadb87d366f51969271778423b455:


# 2016 November 11
#
# 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.
#
#***********************************************************************
# Test the virtual table interface. In particular the xBestIndex
# method.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix bestindex4

ifcapable !vtab {
  finish_test
  return
}

#-------------------------------------------------------------------------
# Virtual table callback for a virtual table named $tbl.
#
# The table created is:
#
#      "CREATE TABLE t1 (id, host, class)"
#
# The virtual table supports == operators on a subset of its columns. The
# exact subset depends on the value of bitmask paramater $param.
#
#   0x01 - == on "id" supported
#   0x02 - == on "host" supported
#   0x04 - == on "class" supported
#
# $param also supports the following bits:
#
#   0x08 - ignore the "usable" flag (malfunction)
#
#
#  
proc vtab_cmd {param method args} {
  switch -- $method {
    xConnect {
      return "CREATE TABLE t1(id TEXT, host TEXT, class TEXT)"
    }

    xBestIndex {
      foreach {clist orderby mask} $args {}

      set ret [list]

      set use use


      for {set i 0} {$i < [llength $clist]} {incr i} {
        array unset C
        array set C [lindex $clist $i]
        if { ($C(usable) || ($param & 0x08)) 
          && $C(op)=="eq" && ($param & 1<<$C(column))
        } {
          lappend ret $use $i
          break
        }
      }

      set score 1000000
      if {$ret!=""} {
        set score [expr $score / [llength $ret]]
      }
      lappend ret cost $score rows $score

      return $ret
    }

    xFilter {
    }
  }
  return ""
}

register_tcl_module db

for {set param1 0} {$param1<16} {incr param1} {
  for {set param2 0} {$param2<16} {incr param2} {
    reset_db
    register_tcl_module db
    do_execsql_test 1.$param1.$param2.1 "
      CREATE VIRTUAL TABLE t1 USING tcl('vtab_cmd $param1');
      CREATE VIRTUAL TABLE t2 USING tcl('vtab_cmd $param2');
    "

    foreach {tn sql} {
      2 "select t1.id as ID from t1, t2 where t1.id=t2.host and t2.class='xx'"
      3 {
        select t1.id as ID from t1, t2 where t2.class ='xx' and t2.id = t1.host
      }
      4 {
        select t1.id as ID from t1, t2 where t1.host = t2.id and t2. class ='xx'
      }
    } {

      if {($param1 & 0x08)==0 && ($param2 & 0x08)==0} {

        do_execsql_test 1.$param1.$param2.$tn.a $sql {}

      } else {
        do_test 1.$param1.$param2.$tn.b {
          catchsql $sql
            set {} {}
        } {}
      }
    }

  }
}

finish_test