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

Artifact 5409d90d8141881d08285ed1c2c0d8d10fb92069:


# 2013 July 04
#
# 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 tests that the sessions module handles foreign key constraint
# violations when applying changesets as required.
#

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
} 
source [file join [file dirname [info script]] session_common.tcl]
source $testdir/tester.tcl
ifcapable !session {finish_test; return}
set testprefix session9


#--------------------------------------------------------------------
# Basic tests.
#
proc populate_db {} {
  drop_all_tables
  execsql {
    PRAGMA foreign_keys = 1;
    CREATE TABLE p1(a PRIMARY KEY, b);
    CREATE TABLE c1(a PRIMARY KEY, b REFERENCES p1);
    CREATE TABLE c2(a PRIMARY KEY, 
        b REFERENCES p1 DEFERRABLE INITIALLY DEFERRED
    );

    INSERT INTO p1 VALUES(1, 'one');
    INSERT INTO p1 VALUES(2, 'two');
    INSERT INTO p1 VALUES(3, 'three');
    INSERT INTO p1 VALUES(4, 'four');
  }
}

proc capture_changeset {sql} {
  sqlite3session S db main

  foreach t [db eval {SELECT name FROM sqlite_master WHERE type='table'}] {
    S attach $t
  }
  execsql $sql
  set ret [S changeset]
  S delete

  return $ret
}

do_test 1.1 {
  populate_db
  set cc [capture_changeset {
    INSERT INTO c1 VALUES('ii', 2);
    INSERT INTO c2 VALUES('iii', 3);
  }]
  set {} {}
} {}

proc xConflict {args} {
  lappend ::xConflict {*}$args
  return $::conflictret
}

foreach {tn delrow trans conflictargs conflictret} {
  1   2 0 {FOREIGN_KEY 1} OMIT
  2   3 0 {FOREIGN_KEY 1} OMIT
  3   2 1 {FOREIGN_KEY 1} OMIT
  4   3 1 {FOREIGN_KEY 1} OMIT
  5   2 0 {FOREIGN_KEY 1} ABORT
  6   3 0 {FOREIGN_KEY 1} ABORT
  7   2 1 {FOREIGN_KEY 1} ABORT
  8   3 1 {FOREIGN_KEY 1} ABORT
} {

  set A(OMIT)  {0 {}}
  set A(ABORT) {1 SQLITE_CONSTRAINT}
  do_test 1.2.$tn.1 {
    populate_db
    execsql { DELETE FROM p1 WHERE a=($delrow+0) }
    if {$trans} { execsql BEGIN }

    set ::xConflict [list]
    list [catch {sqlite3changeset_apply db $::cc xConflict} msg] $msg
  } $A($conflictret)

  do_test 1.2.$tn.2 { set ::xConflict } $conflictargs

  set A(OMIT)  {1 1}
  set A(ABORT) {0 0}
  do_test 1.2.$tn.3 {
    execsql { SELECT count(*) FROM c1 UNION ALL SELECT count(*) FROM c2 }
  } $A($conflictret)

  do_test 1.2.$tn.4 { expr ![sqlite3_get_autocommit db] } $trans
  do_test 1.2.$tn.5 {
    if { $trans } { execsql COMMIT }
  } {}
}

#--------------------------------------------------------------------
# Test that closing a transaction clears the defer_foreign_keys flag.
#
foreach {tn open noclose close} {
  1 BEGIN {} COMMIT
  2 BEGIN {} ROLLBACK

  3 {SAVEPOINT one} {}                {RELEASE one}
  4 {SAVEPOINT one} {ROLLBACK TO one} {RELEASE one}
} {
  execsql $open
  do_execsql_test 2.$tn.1 { PRAGMA defer_foreign_keys } {0}

  do_execsql_test 2.$tn.2 {
    PRAGMA defer_foreign_keys = 1;
    PRAGMA defer_foreign_keys;
  } {1}

  execsql $noclose
  do_execsql_test 2.$tn.3 { PRAGMA defer_foreign_keys } {1}

  execsql $close
  do_execsql_test 2.$tn.4 { PRAGMA defer_foreign_keys } {0}
}

#--------------------------------------------------------------------
# Test that a cyclic relationship can be inserted and deleted.
#
# This situation does not come up in practice, but testing it serves to 
# show that it does not matter which order parent and child keys 
# are processed in internally when applying a changeset.
#
drop_all_tables

do_execsql_test 3.1 {
  CREATE TABLE t1(a PRIMARY KEY, b);
  CREATE TABLE t2(x PRIMARY KEY, y);
}

# Create changesets as follows:
# 
#   $cc1    - Insert a row into t1.
#   $cc2    - Insert a row into t2.
#   $cc     - Combination of $cc1 and $cc2.
#
#   $ccdel1 - Delete the row from t1.
#   $ccdel2 - Delete the row from t2.
#   $ccdel  - Combination of $cc1 and $cc2.
#
do_test 3.2 {
  set cc1 [capture_changeset {
    INSERT INTO t1 VALUES('one', 'value one');
  }]
  set ccdel1 [capture_changeset { DELETE FROM t1; }]
  set cc2 [capture_changeset {
    INSERT INTO t2 VALUES('value one', 'one');
  }]
  set ccdel2 [capture_changeset { DELETE FROM t2; }]
  set cc [capture_changeset {
    INSERT INTO t1 VALUES('one', 'value one');
    INSERT INTO t2 VALUES('value one', 'one');
  }]
  set ccdel [capture_changeset {
    DELETE FROM t1;
    DELETE FROM t2;
  }]
  set {} {}
} {}

# Now modify the database schema to create a cyclic foreign key dependency
# between tables t1 and t2. This means that although changesets $cc and
# $ccdel can be applied, none of the others may without violating the
# foreign key constraints. 
# 
do_test 3.3 {

  drop_all_tables
  execsql {
    CREATE TABLE t1(a PRIMARY KEY, b REFERENCES t2);
    CREATE TABLE t2(x PRIMARY KEY, y REFERENCES t1);
  }


  proc conflict_handler {args} { return "ABORT" }
  sqlite3changeset_apply db $cc conflict_handler

  execsql {
    SELECT * FROM t1;
    SELECT * FROM t2;
  }
} {one {value one} {value one} one}

do_test 3.3.1 {
  list [catch {sqlite3changeset_apply db $::ccdel1 conflict_handler} msg] $msg
} {1 SQLITE_CONSTRAINT}

do_test 3.3.2 {
  list [catch {sqlite3changeset_apply db $::ccdel2 conflict_handler} msg] $msg
} {1 SQLITE_CONSTRAINT}

do_test 3.3.4.1 {
  list [catch {sqlite3changeset_apply db $::ccdel conflict_handler} msg] $msg
} {0 {}}
do_execsql_test 3.3.4.2 {
  SELECT * FROM t1;
  SELECT * FROM t2;
} {}

do_test 3.5.1 {
  list [catch {sqlite3changeset_apply db $::cc1 conflict_handler} msg] $msg
} {1 SQLITE_CONSTRAINT}
do_test 3.5.2 {
  list [catch {sqlite3changeset_apply db $::cc2 conflict_handler} msg] $msg
} {1 SQLITE_CONSTRAINT}

#--------------------------------------------------------------------
# Test that if a change that affects FK processing is not applied 
# due to a separate constraint, SQLite does not get confused and
# increment FK counters anyway.
#
drop_all_tables
do_execsql_test 4.1 {
  CREATE TABLE p1(x PRIMARY KEY, y);
  CREATE TABLE c1(a PRIMARY KEY, b REFERENCES p1);
  INSERT INTO p1 VALUES(1,1);
}

do_execsql_test 4.2.1 {
  BEGIN;
    PRAGMA defer_foreign_keys = 1;
    INSERT INTO c1 VALUES('x', 'x');
}
do_catchsql_test 4.2.2 { COMMIT } {1 {FOREIGN KEY constraint failed}}
do_catchsql_test 4.2.3 { ROLLBACK } {0 {}}

do_execsql_test 4.3.1 {
  BEGIN;
    PRAGMA defer_foreign_keys = 1;
    INSERT INTO c1 VALUES(1, 1);
}
do_catchsql_test 4.3.2 { 
  INSERT INTO c1 VALUES(1, 'x') 
} {1 {UNIQUE constraint failed: c1.a}}

do_catchsql_test 4.3.3 { COMMIT } {0 {}}
do_catchsql_test 4.3.4 { BEGIN ; COMMIT } {0 {}}

#--------------------------------------------------------------------
# Test that if a DELETE change cannot be applied due to an 
# SQLITE_CONSTRAINT error thrown by a trigger program, things do not
# go awry.

drop_all_tables
reset_db
do_execsql_test 5.1 {
  CREATE TABLE x1(x PRIMARY KEY, y);
  CREATE TABLE x2(x PRIMARY KEY, y);
  INSERT INTO x2 VALUES(1, 1);
  INSERT INTO x1 VALUES(1, 1);
}

set ::cc [changeset_from_sql { DELETE FROM x1; }]

do_execsql_test 5.2 {
  INSERT INTO x1 VALUES(1, 1);
  CREATE TRIGGER tr1 AFTER DELETE ON x1 BEGIN
    INSERT INTO x2 VALUES(old.x, old.y);
  END;
} {}

proc conflict_handler {args} { return "ABORT" }
do_test 5.3 {
  list [catch {sqlite3changeset_apply db $::cc conflict_handler} msg] $msg
} {1 SQLITE_ABORT}

do_execsql_test 5.4 {
  SELECT * FROM X1;
} {1 1}

finish_test