connect-by-vs-with-recursive-oracle.sql

connect-by-vs-with-recursive-oracle.sql

-- Copyright Data Geekery GmbH
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- This version displays relative execution times (fastest execution = 1)
-- According to our understanding of Oracle licensing, such benchmark results may be published
-- as they cannot be compared to other databases and do not provide absolute time values
SET SERVEROUTPUT ON

ALTER SYSTEM FLUSH SHARED_POOL;
ALTER SYSTEM FLUSH BUFFER_CACHE;

CREATE TABLE results (
  run     NUMBER(2),
  stmt    NUMBER(2),
  elapsed NUMBER
);

DECLARE
  v_ts TIMESTAMP WITH TIME ZONE;
  v_repeat CONSTANT NUMBER := 2000;
BEGIN

  -- Repeat the whole benchmark several times to avoid warmup penalty
  FOR r IN 1..5 LOOP
    v_ts := SYSTIMESTAMP;

    FOR i IN 1..v_repeat LOOP
      FOR rec IN (
        select *
        from (
          with T(A) as (
            select 1 from dual
            union all
            select A + 1 from T
            where A < 10
          )
          select A from T
        )
      ) LOOP
        NULL;
      END LOOP;
    END LOOP;

    INSERT INTO results VALUES (r, 1, SYSDATE + ((SYSTIMESTAMP - v_ts) * 86400) - SYSDATE);
    v_ts := SYSTIMESTAMP;

    FOR i IN 1..v_repeat LOOP
      FOR rec IN (
        SELECT level
        FROM dual
        CONNECT BY level <= 10
      ) LOOP
        NULL;
      END LOOP;
    END LOOP;

    INSERT INTO results VALUES (r, 2, SYSDATE + ((SYSTIMESTAMP - v_ts) * 86400) - SYSDATE);
  END LOOP;

  FOR rec IN (
    SELECT
      run, stmt,
      CAST(elapsed / MIN(elapsed) OVER() AS NUMBER(10, 5)) ratio
    FROM results
  )
  LOOP
    dbms_output.put_line('Run ' || rec.run ||
      ', Statement ' || rec.stmt ||
      ' : ' || rec.ratio);
  END LOOP;

  dbms_output.put_line('');
  dbms_output.put_line('Copyright Data Geekery GmbH');
  dbms_output.put_line('https://www.jooq.org/benchmark');
END;
/

DROP TABLE results;