Re: segfault in hot standby for hash indexes

On Wed, Mar 22, 2017 at 3:39 PM, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> wrote:
> Hi,
>
> On Wed, Mar 22, 2017 at 8:41 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> To fix this, I think we should pass 'REGBUF_KEEP_DATA' while
> registering the buffer. Something like this,
>
> - XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
> + XLogRegisterBuffer(0, buf, REGBUF_STANDARD |
> REGBUF_KEEP_DATA);
>
> Attached is the patch that fixes this issue.
>

I think this will work, but not sure if there is a merit to deviate
from what btree does to handle this case. One thing I find slightly
awkward in hash_xlog_vacuum_get_latestRemovedXid() is that you are
using a number of tuples registered as part of fixed data
(xl_hash_vacuum_one_page) to traverse the data registered as buf data.
I think it will be better if we register offsets also in fixed part of
data as we are doing btree case.

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