Re: pg_verify_checksums failure with hash indexes

On Tue, Sep 4, 2018 at 10:49 AM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
> On Tue, Sep 4, 2018 at 10:14 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>> On Mon, Sep 3, 2018 at 2:44 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>>> On Mon, Sep 3, 2018 at 8:37 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>>> > On Sat, Sep 1, 2018 at 10:28 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>>> >>
>>> >> I think if we compute with below formula which I suggested upthread
>>> >>
>>> >> #define HASH_MAX_BITMAPS                       Min(BLCKSZ / 8, 1024)
>>> >>
>>> >> then for BLCKSZ 8K and bigger, it will remain the same value where it
>>> >> does not overrun.  And, for the small BLCKSZ, I think it will give
>>> >> sufficient space for the hash map. If the BLCKSZ is 1K then the sizeof
>>> >> (HashMetaPageData) + sizeof (HashPageOpaque) = 968 which is very close
>>> >> to the BLCKSZ.
>>> >>
>>> >
>>> > Yeah, so at 1K, the value of HASH_MAX_BITMAPS will be 128 as per above
>>> > formula which is what it was its value prior to the commit 620b49a1.
>>> > I think it will be better if you add a comment in your patch
>>> > indicating the importance/advantage of such a formula.
>>> >
>>> I have added the comments.
>>>
>>
>
> In my previous patch mistakenly I put Max(BLCKSZ / 8, 1024) instead of
> Min(BLCKSZ / 8, 1024).   I have fixed the same.
>
>> Thanks, I will look into it.  Can you please do some pg_upgrade tests
>> to ensure that this doesn't impact the upgrade?  You can create
>> hash-index and populate it with some data in version 10 and try
>> upgrading to 11 after applying this patch.  You can also try it with
>> different block-sizes.
>>
> Ok, I will do that.
>

I have tested pg_upgrade with different block size (1K, 4K, 8K, 32K).
The upgrade is working fine from v10 to v11 and I am able to fetch
data with index scan on the hash index after an upgrade.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com