On Sat, Jan 23, 2021 at 9:56 AM Dilip Kumar <dilipbal...@gmail.com> wrote: > > On Fri, Jan 22, 2021 at 2:18 AM Robert Haas <robertmh...@gmail.com> wrote: > > > > On Mon, Jan 18, 2021 at 9:42 PM Yugo NAGATA <nag...@sraoss.co.jp> wrote: > > > If it is acceptable that pg_is_wal_replay_paused() makes users wait, > > > I'm ok for the current interface. I don't feel the need of > > > pg_is_wal_replay_paluse_requeseted(). > > > > Another idea could be that pg_is_wal_replay_paused() could be changed > > to text, and the string could be either 'paused' or 'pause requested' > > or 'not paused'. That way we'd be returning a direct representation of > > the state we're keeping in memory. Some of the complexity in this > > discussion seems to come from trying to squeeze 3 possibilities into a > > Boolean. > > > > Let's also consider that we don't really know whether the client wants > > us to wait or not, and different clients may want different things, or > > maybe not, but we don't really know at this point. If we provide an > > interface that waits, and the client doesn't want to wait but just > > know the current state, they don't necessarily have any great options. > > If we provide an interface that doesn't wait, and the client wants to > > wait, it can poll until it gets the answer it wants. Polling can be > > inefficient, but anybody who is writing a tool that uses this should > > be able to manage an algorithm with some reasonable back-off behavior > > (e.g. try after 10ms, 20ms, keep doubling, max of 5s, or something of > > that sort), so I'm not sure there's actually any real problem in > > practice. So to me it seems more likely that an interface that is > > based on waiting will cause difficulty for tool-writers than one that > > does not. > > > > Other people may feel differently, of course... > > I think this is the better way of handling this. So +1 from my side, > I will send an updated patch.
Please find the patch for the same. I haven't added a test case for this yet. I mean we can write a test case to pause the recovery and get the status. But I am not sure that we can really write a reliable test case for 'pause requested' and 'paused'. -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com
v6-0001-pg_is_wal_replay_paused-will-return-the-status-of.patch
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