Fix an AR test of relations_test when using Oracle

[koic]

Summary

This PR fixes the following failure test when using Oracle (11g) .

%  ruby -v
ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-linux]
% ARCONN=oracle bundle exec ruby -w -Itest test/cases/relations_test.rb -n "test_relations_don't_load_all_records_in_#inspect"
/home/vagrant/src/rails/activesupport/lib/active_support/core_ext/enumerable.rb:20: warning: method redefined; discarding old sum
Using oracle
Run options: -n test_relations_don't_load_all_records_in_#inspect --seed 24645

# Running:

F

Finished in 0.994688s, 1.0053 runs/s, 1.0053 assertions/s.

  1) Failure:
RelationTest#test_relations_don't_load_all_records_in_#inspect [test/cases/relations_test.rb:1907]:
Query pattern(s) /LIMIT/ not found.
Queries:
SELECT  "POSTS".* FROM "POSTS" WHERE ROWNUM <= :a1

1 runs, 1 assertions, 1 failures, 0 errors, 0 skips

Oracle does not support LIMIT clause. Oracle Adapter uses ROWNUM instead of that.

Other Information

I confirmed that there is the same test fails on 5-1-stable branch.

[rails-bot]

r? @eileencodes

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[yahonda]

@koic Thanks for opening a pull request. Would you include Oracle 12c new syntax fetch first n rows only.

$ ARCONN=oracle bundle exec ruby -w -Itest test/cases/relations_test.rb -n "test_relations_don't_load_all_records_in_#inspect"
/home/yahonda/git/rails/activesupport/lib/active_support/core_ext/enumerable.rb:20: warning: method redefined; discarding old sum
Using oracle
Run options: -n test_relations_don't_load_all_records_in_#inspect --seed 41532

# Running:

F

Finished in 1.202606s, 0.8315 runs/s, 0.8315 assertions/s.

  1) Failure:
RelationTest#test_relations_don't_load_all_records_in_#inspect [test/cases/relations_test.rb:1905]:
Query pattern(s) /LIMIT/ not found.
Queries:
SELECT  "POSTS".* FROM "POSTS" FETCH FIRST :a1 ROWS ONLY

1 runs, 1 assertions, 1 failures, 0 errors, 0 skips
$

There was a similar pull request #26067.

[koic]

@yahonda Thanks for your advice. I've included an Oracle 12c new syntax FETCH FIRST n ROWS ONLY with reference to your advice.

[yahonda]

Thanks for updating the pull request.

Now this test passes with Oracle Database 12c

$ ARCONN=oracle bundle exec ruby -w -Itest test/cases/relations_test.rb -n "test_relations_don't_load_all_records_in_#inspect"
/home/yahonda/git/rails/activesupport/lib/active_support/core_ext/enumerable.rb:20: warning: method redefined; discarding old sum
Using oracle
Run options: -n test_relations_don't_load_all_records_in_#inspect --seed 56674

# Running:

.

Finished in 1.128852s, 0.8859 runs/s, 0.8859 assertions/s.

1 runs, 1 assertions, 0 failures, 0 errors, 0 skips
$