Re: Logical decoding on standby

On 30 March 2017 at 18:16, Andres Freund <andres(at)anarazel(dot)de> wrote:

>> /*
>> * Each page of XLOG file has a header like this:
>> */
>> -#define XLOG_PAGE_MAGIC 0xD097 /* can be used as WAL version indicator */
>> +#define XLOG_PAGE_MAGIC 0xD100 /* can be used as WAL version indicator */
>
> We normally only advance this by one, it's not tied to the poistgres version.

That was my addition. I rounded it up cos this is release 10. No biggie.

(Poistgres? Is that the Manhattan spelling?)

> I'm sorry, but to me this patch isn't ready. I'm also doubtful that it
> makes a whole lot of sense on its own, without having finished the
> design for decoding on a standby - it seems quite likely that we'll have
> to redesign the mechanisms in here a bit for that. For 10 this seems to
> do nothing but add overhead?

I'm sure we can reword the comments.

We've been redesigning the mechanisms for 2 years now, so it seems
unlikely that further redesign can be required. If it is required,
this patch is fairly low touch and change is possible later,
incremental development etc. As regards overhead, this adds a small
amount of time to a background process executed every 10 secs,
generates no new WAL records.

So I don't see any reason not to commit this feature, after the minor
corrections.

--
Simon Riggs http://www.2ndQuadrant.com/
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