3-3-4. 방법에 따른 실제 I/O 검증해 보기

-- [SQL-3-3-4-a]

SELECT  t1.ctid, t1.ord_no, t1.mbr_id, t1.shop_id
FROM    startdbpg.tr_ord_big t1
WHERE   t1.ord_no = 6;
SQL
복사

-- [SQL-3-3-4-1-a]

EXPLAIN (ANALYZE,BUFFERS,COSTS OFF)
SELECT  /*+ SeqScan(t1) */
        t1.ctid, t1.ord_no, t1.mbr_id, t1.shop_id
FROM    startdbpg.tr_ord_big t1
WHERE   t1.ord_no = 6;
SQL
복사

-- [SQL-3-3-4-1-b]

SELECT  t1.relname  ,t1.relpages block_cnt
FROM    pg_class t1
WHERE   t1.oid = 'startdbpg.tr_ord_big'::regclass;
SQL
복사

-- [SQL-3-3-4-2-a]

EXPLAIN (ANALYZE,BUFFERS,COSTS OFF)
SELECT  t1.ctid, t1.ord_no, t1.mbr_id, t1.shop_id
FROM    startdbpg.tr_ord_big t1
WHERE   t1.ord_no = 6;
SQL
복사

-- [SQL-3-3-4-3-a]

EXPLAIN (ANALYZE,BUFFERS,COSTS OFF)
SELECT  t1.ctid, t1.ord_no, t1.mbr_id, t1.shop_id
FROM    startdbpg.tr_ord_big t1
WHERE   t1.ctid = '(0,6)';
SQL
복사