Re: Default order of select datname from pg_database
| От | Elías David |
|---|---|
| Тема | Re: Default order of select datname from pg_database |
| Дата | |
| Msg-id | CANNE3r0-urWBDryg--NQSP7Bt_AAN5n0ug+PTrAtxFUadikMxQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Default order of select datname from pg_database (Tom Lane <tgl@sss.pgh.pa.us>) |
| Список | pgsql-admin |
Ah... I see, that clarifies things. Thank you all for your responses!
All started because I looked a script that is used in our company to backup databases and it seemed odd that the query didn't use an order by sentence which would be helpful, that way I could anticipate when a particular database is going to be backed up, it's easy to fix though so no issues there.
Again thank you all
Best regards
On Apr 19, 2014 10:47 AM, "Tom Lane" <tgl@sss.pgh.pa.us> wrote:
Elías David <elias.moreno.tec@gmail.com> writes:
> By any change, does the following query have an "order by" by default when
> omitted?:
> select datname from pg_database;
No. No SQL query ever has a "default" order by.
> I executed that query against one of my servers and while looking at the
> names it seems complety random, the order is always the same, for instance:
An unqualified query is typically going to result in a sequential scan
of the table, so what you're seeing is the current physical order of the
tuples. This might change after adding/deleting/changing the properties
of a database.
regards, tom lane
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