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psql: Allow queries terminated by semicolons while in pipeline mode

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Currently, the only way to pipe queries in an ongoing pipeline (in a
\startpipeline block) is to leverage the meta-commands able to create
extended queries such as \bind, \parse or \bind_named.

While this is good enough for testing the backend with pipelines, it has
been mentioned that it can also be very useful to allow queries
terminated by semicolons to be appended to a pipeline.  For example, it
would be possible to migrate existing psql scripts to use pipelines by
just adding a set of \startpipeline and \endpipeline meta-commands,
making such scripts more efficient.

Doing such a change is proving to be simple in psql: queries terminated
by semicolons can be executed through PQsendQueryParams() without any
parameters set when the pipeline mode is active, instead of
PQsendQuery(), the default, like pgbench.  \watch is still forbidden
while in a pipeline, as it expects its results to be processed
synchronously.

The large portion of this commit consists in providing more test
coverage, with mixes of extended queries appended in a pipeline by \bind
and friends, and queries terminated by semicolons.

This improvement has been suggested by Daniel Vérité.

Author: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Discussion: https://postgr.es/m/d67b9c19-d009-4a50-8020-1a0ea92366a1@manitou-mail.org
This commit is contained in:
Michael Paquier
2025-03-19 13:34:59 +09:00
parent 0b53c08677
commit 2cce0fe440
5 changed files with 359 additions and 47 deletions
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7
src/bin/psql/command.c
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@@ -3282,6 +3282,13 @@ exec_command_watch(PsqlScanState scan_state, bool active_branch,
int iter = 0;
int min_rows = 0;
if (PQpipelineStatus(pset.db) != PQ_PIPELINE_OFF)
{
pg_log_error("\\watch not allowed in pipeline mode");
clean_extended_state();
success = false;
}
/*
* Parse arguments. We allow either an unlabeled interval or
* "name=value", where name is from the set ('i', 'interval', 'c',