Re: [HACKERS] hash index on unlogged tables doesn't behave as expected

On Thu, Sep 21, 2017 at 4:14 PM, Kyotaro HORIGUCHI
<horiguchi.kyotaro@lab.ntt.co.jp> wrote:
>
> postgres=# create table test (id int primary key, v text);
> postgres=# create index on test using hash (id);
> WARNING:  hash indexes are not WAL-logged and their use is discouraged
>
> But not for for unlogged tables.
>
> postgres=# create unlogged table test (id int primary key, v text);
> postgres=# create index on test using hash (id);
> postgres=# (no warning)
>
> And fails on promotion in the same way.
>
> postgres=# select * from test;
> ERROR:  could not open file "base/13324/16446": No such file or directory
>
> indexcmds.c@965:503
>>   if (strcmp(accessMethodName, "hash") == 0 &&
>>     RelationNeedsWAL(rel))
>>     ereport(WARNING,
>>         (errmsg("hash indexes are not WAL-logged and their use is discouraged")));
>
> Using !RelationUsesLocalBuffers instead fixes that and the
> attached patch is for 9.6. I'm a bit unconfident on the usage of
> logical meaning of the macro but what it does fits there.
>


I think giving an error message like "hash indexes are not WAL-logged
and .." for unlogged tables doesn't seem like a good behavior.


-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com


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