Invalid result from hash_page_items function
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
Attachments:
fix_hash_page_items.patchapplication/octet-stream; name=fix_hash_page_items.patchDownload
diff --git a/contrib/pageinspect/hashfuncs.c b/contrib/pageinspect/hashfuncs.c
index 3d0e3f9..99b61b8 100644
--- a/contrib/pageinspect/hashfuncs.c
+++ b/contrib/pageinspect/hashfuncs.c
@@ -313,10 +313,10 @@ hash_page_items(PG_FUNCTION_ARGS)
fctx = SRF_FIRSTCALL_INIT();
- page = verify_hash_page(raw_page, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
-
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
+ page = verify_hash_page(raw_page, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
+
uargs = palloc(sizeof(struct user_args));
uargs->page = page;
Import Notes
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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
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