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

Artifact 038e3d0789332f3f1d61474f9bbc9c6d08c6bd1783a978f31f38ad82688de601:


# 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 {} {}
        } {}
      }
    }

  }
}

#-------------------------------------------------------------------------
# Test that a parameter passed to a table-valued function cannot be
# used to drive an index. i.e. that in the following:
#
#   SELECT * FROM tbl, vtab(tbl.x);
#
# The implicit constraint "tbl.x = vtab.hidden" is not optimized using
# an index on tbl.x.
#
reset_db
register_tcl_module db
proc vtab_command {method args} {
  switch -- $method {
    xConnect {
      return "CREATE TABLE t1(a, b, c, d HIDDEN)"
    }

    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 [list omit 0 idxnum 555 rows 10 cost 100]
      }
      return [list cost 100000000]
    }

  }

  return {}
}

do_execsql_test 2.0 {
  CREATE VIRTUAL TABLE x1 USING tcl(vtab_command);
  CREATE TABLE t1 (x INT PRIMARY KEY);
} {}

do_eqp_test 2.1 {
  SELECT * FROM t1, x1 WHERE x1.d=t1.x;
} {
  QUERY PLAN
  |--SCAN TABLE x1 VIRTUAL TABLE INDEX 0:
  `--SEARCH TABLE t1 USING COVERING INDEX sqlite_autoindex_t1_1 (x=?)
}

do_eqp_test 2.2 {
  SELECT * FROM t1, x1(t1.x)
} {
  QUERY PLAN
  |--SCAN TABLE t1
  `--SCAN TABLE x1 VIRTUAL TABLE INDEX 555:
}


finish_test