Thread: Add further details to ROW SHARE table level lock modes section
The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/14/explicit-locking.html Description: The ROW SHARE table level lock modes section currently states: ``` Conflicts with the EXCLUSIVE and ACCESS EXCLUSIVE lock modes. The SELECT FOR UPDATE and SELECT FOR SHARE commands acquire a lock of this mode on the target table(s) (in addition to ACCESS SHARE locks on any other tables that are referenced but not selected FOR UPDATE/FOR SHARE). ``` I propose that it would be useful to explicitly state that `SELECT FOR KEY SHARE` AND `SELECT FOR NO KEY UPDATE` commands also acquire the ROW SHARE table level lock on target table(s). That is: ``` Conflicts with the EXCLUSIVE and ACCESS EXCLUSIVE lock modes. The SELECT FOR UPDATE, SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, and SELECT FOR KEY SHARE commands acquire a lock of this mode on the target table(s) (in addition to ACCESS SHARE locks on any other tables that are referenced but not selected FOR UPDATE/FOR SHARE). ``` Thank you for your time.
On 2022-Apr-04, PG Doc comments form wrote:
> I propose that it would be useful to explicitly state that `SELECT FOR KEY
> SHARE` AND `SELECT FOR NO KEY UPDATE` commands also acquire the ROW SHARE
> table level lock on target table(s). That is:
> ```
> Conflicts with the EXCLUSIVE and ACCESS EXCLUSIVE lock modes.
>
> The SELECT FOR UPDATE, SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, and
> SELECT FOR KEY SHARE commands acquire a lock of this mode on the target
> table(s) (in addition to ACCESS SHARE locks on any other tables that are
> referenced but not selected FOR UPDATE/FOR SHARE).
> ```
I agree we need an update here. But the original wording seems a bit
off; I think we should say SELECT is a command, and that the FOR bits
are options thereof. Maybe something like this:
<para>
The <command>SELECT</command> command acquires a lock of this mode
on all tables on which one of the <option>FOR UPDATE</option>,
<option>FOR NO KEY UPDATE</option>,
<option>FOR SHARE</option>, or
<option>FOR KEY SHARE</option> options is specified
(in addition to <literal>ACCESS SHARE</literal> locks on any other
tables that are referenced without any explicit
<option>FOR ...</option> locking option).
</para>
Thoughts?
Grammar check: "one of the a,b,c options IS specified" or "one of the
a,b,c options ARE specified"?
--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
Op 13-04-2022 om 20:00 schreef Alvaro Herrera: > On 2022-Apr-04, PG Doc comments form wrote: > >> I propose that it would be useful to explicitly state that `SELECT FOR KEY >> SHARE` AND `SELECT FOR NO KEY UPDATE` commands also acquire the ROW SHARE >> table level lock on target table(s). That is: >> ``` >> Conflicts with the EXCLUSIVE and ACCESS EXCLUSIVE lock modes. >> >> The SELECT FOR UPDATE, SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, and >> SELECT FOR KEY SHARE commands acquire a lock of this mode on the target >> table(s) (in addition to ACCESS SHARE locks on any other tables that are >> referenced but not selected FOR UPDATE/FOR SHARE). >> ``` > > I agree we need an update here. But the original wording seems a bit > off; I think we should say SELECT is a command, and that the FOR bits > are options thereof. Maybe something like this: > > <para> > The <command>SELECT</command> command acquires a lock of this mode > on all tables on which one of the <option>FOR UPDATE</option>, > <option>FOR NO KEY UPDATE</option>, > <option>FOR SHARE</option>, or > <option>FOR KEY SHARE</option> options is specified > (in addition to <literal>ACCESS SHARE</literal> locks on any other > tables that are referenced without any explicit > <option>FOR ...</option> locking option). > </para> > > Thoughts? > > Grammar check: "one of the a,b,c options IS specified" or "one of the > a,b,c options ARE specified"? one [...] IS specified