Re: PATCH: pageinspect / add page_checksum and bt_page_items(bytea)

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>
Cc: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PATCH: pageinspect / add page_checksum and bt_page_items(bytea)
Date: 2017-03-14 12:07:21
Message-ID: 20170314120721.pprxhapoqaboj7wc@alvherre.pgsql
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Ashutosh Sharma wrote:

> Yes. But, as i said earlier I am getting negative checksum value for
> page_header as well. Isn't that wrong. For eg. When I debug the
> following query, i could pd_checksum value as '40074' in gdb where
> page_header shows it as '-25462'.

Yes; the point is that this is a pre-existing problem, not one being
introduced with this patch. In SQL we don't have unsigned types, and we
have historically chosen a type with the same width instead of one with
enough width to represent all possible unsigned values. IMO this patch
is doing the right thing; if in the future we want to change that
decision, that's fine but it's a separate patch.

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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