I am getting seq_scan on vtiger_account. Index is not using. Could anyone please tell me what the reason is?
explain analyze select * from vtiger_account LEFT JOIN vtiger_account vtiger_account2 ON vtiger_account.parentid = vtiger_account2.accountid QUERY PLAN ----------------------------------------------------------------------------------------------------------------------------------------------------- Hash Left Join (cost=12506.65..38690.74 rows=231572 width=264) (actual time=776.910..4407.233 rows=231572 loops=1) Hash Cond: ("outer".parentid = "inner".accountid) -> Seq Scan on vtiger_account (cost=0.00..7404.72 rows=231572 width=132) (actual time=0.029..349.195 rows=231572 loops=1) -> Hash (cost=7404.72..7404.72 rows=231572 width=132) (actual time=776.267..776.267 rows=231572 loops=1) -> Seq Scan on vtiger_account vtiger_account2 (cost=0.00..7404.72 rows=231572 width=132) (actual time=0.002..344.879 rows=231572 loops=1) Total runtime: 4640.868 ms (6 rows) vtigercrm504=# set enable_Seqscan = on; SET ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Merge Left Join (cost=0.00..1383629.28 rows=231572 width=264) (actual time=0.166..1924.417 rows=231572 loops=1) Merge Cond: ("outer".parentid = "inner".accountid) -> Index Scan using vtiger_account_parentid_idx on vtiger_account (cost=0.00..642475.34 rows=231572 width=132) (actual time=0.083..483.985 rows=231572 loops=1) -> Index Scan using vtiger_account_pkey on vtiger_account vtiger_account2 (cost=0.00..737836.61 rows=231572 width=132) (actual time=0.074..532.463 rows=300971 loops=1) Total runtime: 2140.326 ms (5 rows) \d vtiger_account Table "public.vtiger_account" Column | Type | Modifiers ---------------+------------------------+-------------------------------- accountid | integer | not null default 0 accountname | character varying(200) | not null parentid | integer | default 0 account_type | character varying(200) | industry | character varying(200) | annualrevenue | integer | default 0 rating | character varying(200) | ownership | character varying(50) | siccode | character varying(50) | tickersymbol | character varying(30) | phone | character varying(30) | otherphone | character varying(30) | email1 | character varying(100) | email2 | character varying(100) | website | character varying(100) | fax | character varying(30) | employees | integer | default 0 emailoptout | character varying(3) | default '0'::character varying notify_owner | character varying(3) | default '0'::character varying Indexes: "vtiger_account_pkey" PRIMARY KEY, btree (accountid) "account_account_type_idx" btree (account_type) "vtiger_account_parentid_idx" btree (parentid)