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  1. pageinspect: Fix use of wrong memory context by hash_page_items.

  1. Invalid result from hash_page_items function

    Masahiko Sawada <sawada.mshk@gmail.com> — 2018-01-25T21:50:59Z

    Hi,

While researching hash index, I found that hash_page_items could
return an invalid result as follows.

postgres(1:1056)=# create table hash_test (c int);
CREATE TABLE
postgres(1:1056)=# insert into hash_test select generate_series(1,50) % 5;
INSERT 0 50
postgres(1:1056)=# create index hash_idx on hash_test using hash (c);
CREATE INDEX
postgres(1:1056)=# create extension pageinspect ;
CREATE EXTENSION
postgres(1:1056)=# select * from hash_page_items(get_raw_page('hash_idx',
4));
itemoffset | ctid | data
------------+--------------------+------------
1 | (0,49) | 3283889963
2 | (2139062143,32639) | 2139062143
3 | (2139062143,32639) | 2139062143
4 | (2139062143,32639) | 2139062143
5 | (2139062143,32639) | 2139062143
6 | (2139062143,32639) | 2139062143
7 | (2139062143,32639) | 2139062143
8 | (2139062143,32639) | 2139062143
9 | (2139062143,32639) | 2139062143
10 | (2139062143,32639) | 2139062143
(10 rows)

This appears at PostgreSQL 10 and current HEAD. The cause of this
seems that hash_page_items allocates the memory space for the page
before switching memory context. AFAICS there is no similar problem in
pageinspect contrib module. Attached patch fixes it.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

  2. Re: Invalid result from hash_page_items function

    Robert Haas <robertmhaas@gmail.com> — 2018-01-26T15:04:14Z

    On Thu, Jan 25, 2018 at 4:50 PM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> This appears at PostgreSQL 10 and current HEAD. The cause of this
> seems that hash_page_items allocates the memory space for the page
> before switching memory context. AFAICS there is no similar problem in
> pageinspect contrib module. Attached patch fixes it.

Committed and back-patched.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

  3. Re: Invalid result from hash_page_items function

    Masahiko Sawada <sawada.mshk@gmail.com> — 2018-01-29T02:25:50Z

    On Sat, Jan 27, 2018 at 12:04 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Thu, Jan 25, 2018 at 4:50 PM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>> This appears at PostgreSQL 10 and current HEAD. The cause of this
>> seems that hash_page_items allocates the memory space for the page
>> before switching memory context. AFAICS there is no similar problem in
>> pageinspect contrib module. Attached patch fixes it.
>
> Committed and back-patched.
>

Thank you!

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center