SELECT on IOT slow

Question

I have a big index organized table (> 50 million entries):
CREATE TABLE MEASURE_DATA_IOT (
  SERIAL          VARCHAR2(255) NOT NULL,
  DEVICE_TYPE     NUMBER(10,0) NOT NULL,
  DEVICE_ID     VARCHAR2(255) NOT NULL,
  VALUE_TYPE      NUMBER(10,0) NOT NULL,
  TIMESTAMP       TIMESTAMP(6) NOT NULL,
  VALUE           FLOAT NOT NULL,
  CONSTRAINT MEASURE_DATA_IOT_PK PRIMARY KEY(SERIAL, DEVICE_TYPE, DEVICE_ID, VALUE_TYPE, TIMESTAMP)
ORGANIZATION INDEX;
-- a SERIAL as some DEVICEs with TYPE and ID, each DEVICE produces many VALUEs that have a TYPE and a TIMESTAMPSelects using all columns of the PK are very fast. But other querie are very slow (> 10 min.):
-- DEVICEs of TYPE 1 belong to a given SERIAL?
SELECT
  md.serial,
  md.device_id
FROM
  measure_data_iot md
WHERE
  md.serial = :serial
  AND md.device_type=1
GROUP BY
  md.serial,
  md.device_id;
ORDER BY
  md.serial,
  md.device_id;
-- last activity on a given SERIAL?
select max(md.TIMESTAMP) from MEASURE_DATA_IOT md where md.SERIAL = :serial;Any idea, who to speed up those queries?

Answer 1

>
> Any idea, who to speed up those queries?
yes.
start with reading this thread --> [HOW TO: Post a SQL statement tuning request - template posting|http://forums.oracle.com/forums/thread.jspa?threadID=863295]