Horton

RE: Parallel copy

Hou, Zhijie <houzj.fnst@cn.fujitsu.com>

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From: "Hou, Zhijie" <houzj.fnst@cn.fujitsu.com>
To: vignesh C <vignesh21@gmail.com>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, "PostgreSQL Hackers" <pgsql-hackers@lists.postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2020-12-23T09:35:25Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Allow WaitLatch() to be used without a latch.

  2. Add %P to log_line_prefix for parallel group leader

  3. Include replication origins in SQL functions for commit timestamp

  4. Avoid useless buffer allocations during binary COPY FROM.

Hi

> Yes this optimization can be done, I will handle this in the next patch
> set.
> 

I have a suggestion for the parallel safety-check.

As designed, The leader does not participate in the insertion of data.
If User use (PARALLEL 1), there is only one worker process which will do the insertion.

IMO, we can skip some of the safety-check in this case, becase the safety-check is to limit parallel insert.
(except temporary table or ...)

So, how about checking (PARALLEL 1) separately ?
Although it looks a bit complicated, But (PARALLEL 1) do have a good performance improvement.

Best regards,
houzj