| From: | Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> |
|---|---|
| To: | Mike Lissner <mlissner(at)michaeljaylissner(dot)com> |
| Cc: | pgsql-general(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Does converting an indexed varchar to text rewrite its index? Docs say so, tests say no. |
| Date: | 2020-01-23 19:28:44 |
| Message-ID: | 7c433efb-0a46-1ab2-930a-04e83efa31af@aklaver.com |
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| Lists: | pgsql-general |
On 1/23/20 11:17 AM, Mike Lissner wrote:
> Thanks Adrian. Is there a reason that the index rebuild is nearly
> instant during the ALTER command as opposed to when you build it from
> scratch?
Well it did not rebuilt the index("t1_name_idx") you created on name.
>
> Does it have to do with why this is called a "toast" index?
Certain data types(those that have varlena) can have portions of their
data stored in an auxiliary table in a compressed(or not) form. For all
the details see:
https://www.postgresql.org/docs/12/storage-toast.html
The index is the one on this auxiliary table.
>
> DEBUG: building index "pg_toast_37609_index" on table "pg_toast_37609"
>
> Thanks for the feedback. I really appreciate it and it's super
> interesting to learn about.
>
> Mike
>
--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com
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