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help / color / mirror / Atom feedFrom: Chao Li <li.evan.chao@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Cc: Michael Paquier <michael.paquier@gmail.com>
Cc: Xuneng Zhou <xunengzhou@gmail.com>
Subject: Re: Fix pg_stat_wal_receiver to show CONNECTING status
Date: Wed, 20 May 2026 15:53:38 +0800
Message-ID: <75CDE990-29D5-4D5C-BFE1-3840F19C0163@gmail.com> (raw)
In-Reply-To: <ag00OeH1sbt5ie_6@paquier.xyz>
References: <EF91FF76-1E2B-4F3B-9162-290B4DC517FF@gmail.com>
<agxr29Hsz7FjxzlN@paquier.xyz>
<1F153E64-B791-42FA-A60A-64813B20B81E@gmail.com>
<ag00OeH1sbt5ie_6@paquier.xyz>
> On May 20, 2026, at 12:10, Michael Paquier <michael@paquier.xyz> wrote:
>
> On Wed, May 20, 2026 at 09:47:40AM +0800, Chao Li wrote:
>> I just read v2, and it is actually the first solution I tried. The
>> reason I gave up on that approach and switched to the implementation
>> in v1 is that it may wrongly report last_msg_send_time,
>> last_msg_receipt_time, and latest_end_time.
>
> As of the code, we have the following at the top of WalReceiverMain()
> before the first connection attempt:
> /* Initialise to a sanish value */
> now = GetCurrentTimestamp();
> walrcv->lastMsgSendTime =
> walrcv->lastMsgReceiptTime = walrcv->latestWalEndTime = now;
>
Was that okay because walrcv->ready_to_display was false, so the sane initial value would not show up through pg_stat_wal_receiver?
> And the state of v2 is actually fine, because we finish by reporting
> in the SQL calls values that represent the state the WAL receiver is
> initialized at based on what the code does. It would be IMO an issue
> to hide this information, as they can offer hits about the moment when
> we've begun a connection.
> --
> Michael
With v2, slot_name, sender_host, sender_port, and conninfo are already left NULL while the receiver is in CONNECTING state. I feel we don't have to show the timestamp fields either. Since the columns are named last_msg_send_time and last_msg_receipt_time, users may naturally interpret them as the last time a message was sent to or received from
the primary. If we show the standby server start time in those columns, I am afraid that could be confusing.
But I think it might be useful to show the *_lsn and *_tli values in CONNECTING state if they are available.
Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/
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To: pgsql-hackers@postgresql.org
Cc: li.evan.chao@gmail.com, michael@paquier.xyz, michael.paquier@gmail.com, xunengzhou@gmail.com
Subject: Re: Fix pg_stat_wal_receiver to show CONNECTING status
In-Reply-To: <75CDE990-29D5-4D5C-BFE1-3840F19C0163@gmail.com>
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