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COUNT(*) vs COUNT(1) in Oracle
-- 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
CREATE TABLE t (i INT);
INSERT INTO t SELECT level FROM dual CONNECT BY level <= 500000;
INSERT INTO t SELECT 500000 + level FROM dual CONNECT BY level <= 500000;
COMMIT;
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 := 100;
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 COUNT(*) 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 COUNT(1) FROM t
) 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,
CAST(AVG(elapsed) OVER (PARTITION BY stmt) / MIN(elapsed) OVER() AS NUMBER(10, 5)) avg_ratio
FROM results
ORDER BY run, stmt
)
LOOP
dbms_output.put_line('Run ' || rec.run ||
', Statement ' || rec.stmt ||
' : ' || rec.ratio || ' (avg : ' || rec.avg_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;
DROP TABLE t;
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