| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Mohsen SM <mohsensoodkhah(at)gmail(dot)com> |
| Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: varchar_transform |
| Date: | 2014-02-25 16:54:06 |
| Message-ID: | CA+TgmoZZmTQEX3OR6d7P5=_6obhYSnadps57zf9Rdz-T2jau8g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Feb 24, 2014 at 2:11 AM, Mohsen SM <mohsensoodkhah(at)gmail(dot)com> wrote:
> when did use varchar_transform function?
> src/backend/uitls/adt/varchar.c.
The main point of that machinery is that if you do something like
ALTER TABLE zot ALTER COLUMN thunk SET DATA TYPE varchar(30) on a
column that is currently varchar(20), it won't feel obliged to rewrite
the table. That function lets it figure out that anything that's a
valid varchar(20) value is also a valid varchar(30) value.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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