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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: 2025-03-19T04:49:23Z
Lists: pgsql-hackers 
On Tue, Mar 18, 2025 at 09:55:21AM +0100, Anthonin Bonnefoy wrote:
> I've added additional tests when piping queries with ';':
> - I've reused the same scenario with \sendpipeline: single query,
> multiple queries, flushes, syncs, using COPY...
> - Using ';' will replace the unnamed prepared statement. It's a bit
> different from expected as a simple query will delete the unnamed
> prepared statement.
> - Sending an extended query prepared with \bind using a ';' on a
> newline, though this is not specific to pipelining. The scanned
> semicolon triggers the call to SendQuery, processing the buffered
> extended query. It's a bit unusual but that's the current behaviour.

The tests could be much more organized, particularly for the "sinple"
and "multiple" and COPY cases, rather than being treated as two
different groups at different locations of psql_pipeline.sql.  I've
spent some time reorganizing all that.

A second thing that was a bit itchy is the use of ";" for what's a
semicolon, and we use this term in the psql docs to refer to queries
terminated by that.  The whole paragraph could be simplified a bit
more, mentioning that everything in a pipeline uses the extended
protocol, while \bind & co are more like options.  The description of
PIPELINE_COMMAND_COUNT could be simpler, and the part about the
pending results can be more general now so I've removed it.

With all that set, I've applied the patch.  If you have more
suggestions, please feel free to mention them.
--
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