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Re: Add Pipelining support in psql

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Cc: Daniel Verite <daniel@manitou-mail.org>, Jelte Fennema-Nio <postgres@jeltef.nl>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2025-03-18T00:50:27Z
Lists: pgsql-hackers 
On Mon, Mar 17, 2025 at 10:50:50AM +0100, Anthonin Bonnefoy wrote:
> 0001: This introduces the \sendpipeline meta-command and forbid \g in
> a pipeline. This is to fix the formatting options of \g that are not
> supported in a pipeline.

- count 
--------
-     4
-(1 row)

This removal done in the regression tests was not intentional.

I have done some reordering of the code around the new meta-command so
as things are ordered alphabetically, and applied the result.

> 0002: Allows ';' to send a query using extended protocol when within a
> pipeline by using PQsendQueryParams with 0 parameters. It is not
> possible to send parameters with extended protocol this way and
> everything will be propagated through the query string, similar to a
> simple query.

I like the simplicity of what you are doing here, relying on
PSQL_SEND_QUERY being the default so as we use PQsendQueryParams()
with no parameters rather than PQsendQuery() when the pipeline mode is
not off.

How about adding a check on PIPELINE_COMMAND_COUNT when sending a
query through this path?  Should we check for more scenarios with
syncs and flushes as well when sending these queries?
--
Michael

Commits

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

  1. psql: Fix assertion failures with pipeline mode

  2. psql: Rework TAP routine psql_fails_like() to define WAL sender context

  3. psql: Split extended query protocol meta-commands in --help=commands

  4. psql: Improve descriptions of \\flush[request] in --help

  5. psql: Fix incorrect status code returned by \getresults

  6. psql: Allow queries terminated by semicolons while in pipeline mode

  7. psql: Add \sendpipeline to send query buffers while in a pipeline

  8. psql: Fix memory leak with \gx used within a pipeline

  9. psql: Add pipeline status to prompt and some state variables

  10. Add more tests for utility commands in pipelines

  11. psql: Add support for pipelines

  12. Add braces for if block with large comment in psql's common.c