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From: Ron Johnson <ronljohnsonjr@gmail.com>
To: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: Alter the datatype on all tables present in the database (bigint to varchar)
Date: Thu, 14 May 2026 13:20:12 -0400
Message-ID: <CANzqJaBiSXdTSzYS18fc_XUHKUHPkhBu-uz2cW691BLSHnbydw@mail.gmail.com> (raw)
In-Reply-To: <CAHOGQfVo0FWX8mS9FLTmpDOb5XC5-T4qx4ouhw0wOfNeLdahsA@mail.gmail.com>
References: <CAHOGQfVo0FWX8mS9FLTmpDOb5XC5-T4qx4ouhw0wOfNeLdahsA@mail.gmail.com>

On Thu, May 14, 2026 at 11:07 AM Gambhir Singh <gambhir.singh05@gmail.com>
wrote:

> Hi,
>
> Please help me with the best way to change the datatype of a column in a
> all tables in DB from bigint to varchar. Please consider the following
> facts.
>
>
>    - DB Size - 75 TB
>    - Number of tables - ~100
>    - Some tables are partitioned and some are not partitioned.
>    - All partitioned tables are big in size.
>    - For reference, the largest partition size is 4 TB, similarly the
>    size of 10-12 partitions ranges between 1 to 4 TB.
>    - We have indexes and FK on tables.
>
>
With tables that big, and all those FK constraints, logical replication is
probably your only hope for minimal downtime.

If you're running an older major version, this would also be a good time to
upgrade to 17.latest or 18.latest.

And Adrian's question is quite valid: *why*?  Normally, people go the
other way, for efficiency.


>
>    - Physical Replication is configured with 2 standby DBs.
>
> At least you have an existing server with enough disk space!!!



-- 
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

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