From: Vanitha Jaya <e.vanitha@gmail.com>
To: pgsql-performance@postgresql.org
Subject: Internal Operations on LIMIT & OFFSET clause
Date: Tue, 29 Aug 2006 12:51:27 +0530
Message-ID: <b4a87cef0608290021g26965584ld05c3d11b217c2ec@mail.gmail.com> (raw)
Hi Friends,
I have one doubt in LIMIT & OFFSET clause operation.
I have a table "test_limit", and it contain,
SELECT * from test_limit;
s_no | name
------+-------------
1 | anbarasu
8 | egambaram
12 | jyothi
6 | mahalakshmi
4 | maheswari
2 | manju
5 | ramkumar
7 | sangeetha
11 | sasikala
10 | thekkamalai
9 | vivek
13 | ganeshwari
3 | anandhi
(13 rows)
Here, I applied LIMIT clause as bellow.
SELECT * from test_limit LIMIT 5;
s_no | name
------+-------------
1 | anbarasu
8 | egambaram
12 | jyothi
6 | mahalakshmi
4 | maheswari
(5 rows)
In this above query was processed only five records OR all the 13 record
was got and then only 5 record printed.
this is what my doubt.
I tried where clause in above query as bellow.
SELECT * from test_limit where s_no IN (1,2,3,4,5,6,7,8,9) LIMIT 5;
s_no | name
------+-------------
1 | anbarasu
8 | egambaram
6 | mahalakshmi
4 | maheswari
2 | manju
(5 rows)
In this case It should process up to records fulfill the requirement.
i.e atleast it should process 6 records.
My question is it is processed only 6 records (fulfill the requirement) or
all (13) the records.
I also tried ORDER BY clause as bellow.
SELECT * from test_limit ORDER BY s_no LIMIT 5;
s_no | name
------+-----------
1 | anbarasu
2 | manju
3 | anandhi
4 | maheswari
5 | ramkumar
(5 rows)
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To: pgsql-performance@postgresql.org
Cc: e.vanitha@gmail.com
Subject: Re: Internal Operations on LIMIT & OFFSET clause
In-Reply-To: <b4a87cef0608290021g26965584ld05c3d11b217c2ec@mail.gmail.com>
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