On Tue, 24 Dec 2019 07:07:35 +0000 "tsunakawa.ta...@fujitsu.com" <tsunakawa.ta...@fujitsu.com> wrote:
> From: Yugo Nagata <nag...@sraoss.co.jp> > > On Mon, 23 Dec 2019 08:08:53 +0000 > > "tsunakawa.ta...@fujitsu.com" <tsunakawa.ta...@fujitsu.com> wrote: > > > How about unlogged tables ? I thought the point of using a temp table is > > > to > > avoid WAL overhead. > > > > Hmm... this might be another option. However, if we use unlogged tables, > > we will need to create them in a special schema similar to pg_toast > > to split this from user tables. Otherwise, we need to create and drop > > unlogged tables repeatedly for each session. > > Maybe we can create the work tables in the same schema as the materialized > view, following: > > * Prefix the table name to indicate that the table is system-managed, thus > alluding to the user that manually deleting the table would break something. > This is like the system attribute __imv_count you are proposing. > > * Describe the above in the manual. Columns of serial and bigserial data > type similarly create sequences behind the scenes. > > * Make the work tables depend on the materialized view by recording the > dependency in pg_depend, so that Dropping the materialized view will also > drop its work tables. Maybe it works, but instead of using special names for work tables, we can also create a schema whose name is special and place work tables in this. This will not annoy users with information they are not interested in when, for example, psql meta-commands like \d are used. Anyway, I understood it is better to avoid creating and dropping temporary tables during view maintenance per statement. -- Yugo Nagata <nag...@sraoss.co.jp>
