[BUGS] BUG #14750: Seq Scan instead of Index Scan works without limitation

The following bug has been logged on the website:

Bug reference:      14750
Logged by:          Alexey Markevich
Email address:      buhhunyx@tut.by
PostgreSQL version: 9.5.7
Operating system:   Windows X64
Description:

1) Create initial structure [1].

2) explain analyze SELECT * FROM accounts WHERE accountid = 'accountId50';
Index Scan using accounts_pkey on accounts  (cost=0.15..8.17 rows=1
width=272) (actual time=0.022..0.022 rows=1 loops=1)  Index Cond: ((accountid)::text = 'accountId50'::text)Planning
time:0.201 msExecution time: 0.045 ms
 

3) reindex table ACCOUNTS;

4) explain analyze SELECT * FROM accounts WHERE accountid = 'accountId50';
Seq Scan on accounts  (cost=0.00..2.50 rows=1 width=142) (actual
time=0.024..0.037 rows=1 loops=1)  Filter: ((accountid)::text = 'accountId50'::text)  Rows Removed by Filter:
119Planningtime: 0.095 msExecution time: 0.060 ms
 

Expected something like

explain analyze SELECT * FROM accounts WHERE accountid = 'accountId50' limit
1;
Limit  (cost=0.00..2.50 rows=1 width=142) (actual time=0.017..0.017 rows=1
loops=1)  ->  Seq Scan on accounts  (cost=0.00..2.50 rows=1 width=142) (actual
time=0.015..0.015 rows=1 loops=1)        Filter: ((accountid)::text = 'accountId50'::text)        Rows Removed by
Filter:50Planning time: 0.091 msExecution time: 0.033 ms
 

1. CREATE TABLE ACCOUNTS
(
ACCOUNTID VARCHAR(36) NOT NULL,
ACCOUNTNAME VARCHAR(200) NOT NULL,
ACCOUNTEMAIL VARCHAR (200),
PRIMARY KEY (ACCOUNTID),
UNIQUE (ACCOUNTNAME)
);

INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId00',
'accountId00');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId01',
'accountId01');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId02',
'accountId02');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId03',
'accountId03');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId04',
'accountId04');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId05',
'accountId05');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId06',
'accountId06');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId07',
'accountId07');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId08',
'accountId08');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId09',
'accountId09');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId10',
'accountId10');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId11',
'accountId11');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId12',
'accountId12');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId13',
'accountId13');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId14',
'accountId14');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId15',
'accountId15');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId16',
'accountId16');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId17',
'accountId17');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId18',
'accountId18');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId19',
'accountId19');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId20',
'accountId20');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId21',
'accountId21');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId22',
'accountId22');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId23',
'accountId23');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId24',
'accountId24');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId25',
'accountId25');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId26',
'accountId26');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId27',
'accountId27');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId28',
'accountId28');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId29',
'accountId29');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId30',
'accountId30');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId31',
'accountId31');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId32',
'accountId32');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId33',
'accountId33');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId34',
'accountId34');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId35',
'accountId35');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId36',
'accountId36');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId37',
'accountId37');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId38',
'accountId38');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId39',
'accountId39');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId40',
'accountId40');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId41',
'accountId41');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId42',
'accountId42');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId43',
'accountId43');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId44',
'accountId44');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId45',
'accountId45');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId46',
'accountId46');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId47',
'accountId47');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId48',
'accountId48');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId49',
'accountId49');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId50',
'accountId50');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId51',
'accountId51');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId52',
'accountId52');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId53',
'accountId53');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId54',
'accountId54');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId55',
'accountId55');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId56',
'accountId56');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId57',
'accountId57');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId58',
'accountId58');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId59',
'accountId59');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId60',
'accountId60');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId61',
'accountId61');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId62',
'accountId62');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId63',
'accountId63');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId64',
'accountId64');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId65',
'accountId65');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId66',
'accountId66');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId67',
'accountId67');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId68',
'accountId68');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId69',
'accountId69');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId70',
'accountId70');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId71',
'accountId71');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId72',
'accountId72');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId73',
'accountId73');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId74',
'accountId74');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId75',
'accountId75');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId76',
'accountId76');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId77',
'accountId77');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId78',
'accountId78');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId79',
'accountId79');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId80',
'accountId80');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId81',
'accountId81');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId82',
'accountId82');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId83',
'accountId83');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId84',
'accountId84');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId85',
'accountId85');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId86',
'accountId86');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId87',
'accountId87');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId88',
'accountId88');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId89',
'accountId89');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId90',
'accountId90');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId91',
'accountId91');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId92',
'accountId92');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId93',
'accountId93');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId94',
'accountId94');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId95',
'accountId95');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId96',
'accountId96');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId97',
'accountId97');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId98',
'accountId98');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId99',
'accountId99');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId100',
'accountId100');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId101',
'accountId101');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId102',
'accountId102');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId103',
'accountId103');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId104',
'accountId104');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId105',
'accountId105');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId106',
'accountId106');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId107',
'accountId107');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId108',
'accountId108');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId109',
'accountId109');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId110',
'accountId110');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId111',
'accountId111');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId112',
'accountId112');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId113',
'accountId113');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId114',
'accountId114');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId115',
'accountId115');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId116',
'accountId116');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId117',
'accountId117');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId118',
'accountId118');
INSERT INTO ACCOUNTS (accountid, accountname) VALUES ('accountId119',
'accountId119');



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