From: Ron <ronljohnsonjr@gmail.com>
To: pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: What to watch out for when ALTERing NUMERIC(38,0) to BIGINT?
Date: Thu, 28 Jul 2022 12:41:41 -0500
Message-ID: <5a747f00-02dc-3922-6506-fef8ccd701bf@gmail.com> (raw)
In-Reply-To: <3421791.1659021999@sss.pgh.pa.us>
References: <a4465ae0-574a-1727-fcdd-1dac49b874c0@gmail.com>
<CAKFQuwZ8su=VAeyNZ6Wj5cU1OoZLQB+B3iPWh49k2yjk4o4ujQ@mail.gmail.com>
<3421791.1659021999@sss.pgh.pa.us>
On 7/28/22 10:26, Tom Lane wrote:
> "David G. Johnston" <david.g.johnston@gmail.com> writes:
>> On Thu, Jul 28, 2022 at 8:13 AM Ron <ronljohnsonjr@gmail.com> wrote:
>>> Besides what's mentioned in
>>> https://www.postgresql.org/docs/12/ddl-alter.html#id-1.5.4.8.10, what
>>> happens *internally* when I run:
>>> ALTER TABLE foo ALTER COLUMN bar TYPE BIGINT;
>> IIUC, that would be the silver lining in all of this - the rewritten table
>> would have zero fragmentation and bloat.
> Yeah. What happens internally is a table rewrite: the entire content
> of the table (and its indexes) is written into a new set of files.
> At commit, the old files are deleted. The main gotchas, for a large
> table, are the transient disk space consumption and the fact that the
> table stays exclusively locked the whole time.
Rewriting a 3TB table doesn't seem appetizing. Fortunately, there's only
one table like that...
--
Angular momentum makes the world go 'round.
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To: pgsql-admin@postgresql.org
Cc: ronljohnsonjr@gmail.com, pgsql-admin@lists.postgresql.org
Subject: Re: What to watch out for when ALTERing NUMERIC(38,0) to BIGINT?
In-Reply-To: <5a747f00-02dc-3922-6506-fef8ccd701bf@gmail.com>
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