Waiting for PostgreSQL 11 – Add psql variables to track success/failure of SQL queries.

On 12nd of September 2017, Tom Lane committed patch:

Add psql variables to track success/failure of SQL queries.
 
 
This patch adds ERROR, SQLSTATE, and ROW_COUNT, which are updated after
every query, as well as LAST_ERROR_MESSAGE and LAST_ERROR_SQLSTATE,
which are updated only when a query fails.  The expected usage of these
is for scripting.
 
Fabien Coelho, reviewed by Pavel Stehule
 
Discussion: https://postgr.es/m/alpine.DEB.2.20..12290@lancre

Continue reading Waiting for PostgreSQL 11 – Add psql variables to track success/failure of SQL queries.

Waiting for PostgreSQL 11 – Add \gdesc psql command.

On 5th of September 2017, Tom Lane committed patch:

Add \gdesc psql command.
 
This command acts somewhat like \g, but instead of executing the query
buffer, it merely prints a description of the columns that the query
result would have.  (Of course, this still requires parsing the query;
if parse analysis fails, you get an error anyway.)  We accomplish this
using an unnamed prepared statement, which should be invisible to psql
users.
 
Pavel Stehule, reviewed by Fabien Coelho
 
Discussion: https://postgr.es/m/CAFj8pRBhYVvO34FU=EKb=nAF5t3b++krKt1FneCmR0kuF5m-QA@mail.gmail.com

Continue reading Waiting for PostgreSQL 11 – Add \gdesc psql command.

Waiting for PostgreSQL 10 – Support \if … \elif … \else … \endif in psql scripting.

On 30th of March 2017, Tom Lane committed patch:

Support \if ... \elif ... \else ... \endif in psql scripting.
 
This patch adds nestable conditional blocks to psql.  The control
structure feature per se is complete, but the boolean expressions
understood by \if and \elif are pretty primitive; basically, after
variable substitution and backtick expansion, the result has to be
"true" or "false" or one of the other standard spellings of a boolean
value.  But that's enough for many purposes, since you can always
do the heavy lifting on the server side; and we can extend it later.
 
Along the way, pay down some of the technical debt that had built up
around psql/command.c:
* Refactor exec_command() into a function per command, instead of
being a 1500-line monstrosity.  This makes the file noticeably longer
because of repetitive function header/trailer overhead, but it seems
much more readable.
* Teach psql_get_variable() and psqlscanslash.l to suppress variable
substitution and backtick expansion on the basis of the conditional
stack state, thereby allowing removal of the OT_NO_EVAL kluge.
* Fix the no-doubt-once-expedient hack of sometimes silently substituting
mainloop.c's previous_buf for query_buf when calling HandleSlashCmds.
(It's a bit remarkable that commands like \r worked at all with that.)
Recall of a previous query is now done explicitly in the slash commands
where that should happen.
 
Corey Huinker, reviewed by Fabien Coelho, further hacking by me
 
Discussion: https://postgr.es/m/CADkLM=c94OSRTnat=LX0ivNq4pxDNeoomFfYvBKM5N_xfmLtAA@mail.gmail.com

Continue reading Waiting for PostgreSQL 10 – Support \if … \elif … \else … \endif in psql scripting.

Waiting for PostgreSQL 10 – psql: Add \gx command

On 7th of March, Stephen Frost committed patch:

psql: Add \gx command
 
It can often be useful to use expanded mode output (\x) for just a
single query.  Introduce a \gx which acts exactly like \g except that it
will force expanded output mode for that one \gx call.  This is simpler
than having to use \x as a toggle and also means that the user doesn't
have to worry about the current state of the expanded variable, or
resetting it later, to ensure a given query is always returned in
expanded mode.
 
Primairly Christoph's patch, though I did tweak the documentation and help
text a bit, and re-indented the tab completion section.
 
Author: Christoph Berg
Reviewed By: Daniel Verite
Discussion: <a href="https://postgr.es/m/20170127132737.6skslelaf4txs6iw%40msg.credativ.de">https://www.postgresql.org/message-id/20170127132737.6skslelaf4txs6iw%40msg.credativ.de

Continue reading Waiting for PostgreSQL 10 – psql: Add \gx command

Waiting for 9.6 – Support \crosstabview in psql

On 8th of April, Alvaro Herrera committed patch:

Support \crosstabview in psql
 
\crosstabview is a completely different way to display results from a
query: instead of a vertical display of rows, the data values are placed
in a grid where the column and row headers come from the data itself,
similar to a spreadsheet.
 
The sort order of the horizontal header can be specified by using
another column in the query, and the vertical header determines its
ordering from the order in which they appear in the query.
 
This only allows displaying a single value in each cell.  If more than
one value correspond to the same cell, an error is thrown.  Merging of
values can be done in the query itself, if necessary.  This may be
revisited in the future.
 
Author: Daniel Verité
<span class="signoff">Reviewed-by: Pavel Stehule, Dean Rasheed</span>

Continue reading Waiting for 9.6 – Support \crosstabview in psql

Waiting for 9.6 – Add a \gexec command to psql for evaluation of computed queries.

On 4th of April, Tom Lane committed patch:

Add a \gexec command to psql for evaluation of computed queries.
 
\gexec executes the just-entered query, like \g, but instead of printing
the results it takes each field as a SQL command to send to the server.
Computing a series of queries to be executed is a fairly common thing,
but up to now you always had to resort to kluges like writing the queries
to a file and then inputting the file.  Now it can be done with no
intermediate step.
 
The implementation is fairly straightforward except for its interaction
with FETCH_COUNT.  ExecQueryUsingCursor isn't capable of being called
recursively, and even if it were, its need to create a transaction
block interferes unpleasantly with the desired behavior of \gexec after
a failure of a generated query (i.e., that it can continue).  Therefore,
disable use of ExecQueryUsingCursor when doing the master \gexec query.
We can still apply it to individual generated queries, however, and there
might be some value in doing so.
 
While testing this feature's interaction with single-step mode, I (tgl) was
led to conclude that SendQuery needs to recognize SIGINT (cancel_pressed)
as a negative response to the single-step prompt.  Perhaps that's a
back-patchable bug fix, but for now I just included it here.
 
Corey Huinker, reviewed by Jim Nasby, Daniel Vérité, and myself

Continue reading Waiting for 9.6 – Add a \gexec command to psql for evaluation of computed queries.

Waiting for 9.6 – psql: Support multiple -c and -f options, and allow mixing them.

On 8th of December, Robert Haas committed patch:

psql: Support multiple -c and -f options, and allow mixing them.
 
To support this, we must reconcile some historical anomalies in the
behavior of -c.  In particular, as a backward-incompatibility, -c no
longer implies --no-psqlrc.
 
Pavel Stehule (code) and Catalin Iacob (documentation).  Review by
Michael Paquier and myself.  Proposed behavior per Tom Lane.

Continue reading Waiting for 9.6 – psql: Support multiple -c and -f options, and allow mixing them.

Waiting for 9.6 – Add psql PROMPT variable showing the pid of the connected to backend.

On 7th of July, Andres Freund committed patch:

Add psql PROMPT variable showing the pid of the connected to backend.
 
The substitution for the pid is %p.
 
Author: Julien Rouhaud
Discussion: <a href="http://git.postgresql.org/gitweb/?p=postgresql.git;a=object;h=116262CF971C844FB6E793F8809B51C6E99D48">116262CF971C844FB6E793F8809B51C6E99D48</a>@BPXM02GP.gisp.nec.co.jp

Continue reading Waiting for 9.6 – Add psql PROMPT variable showing the pid of the connected to backend.

Waiting for 9.6 – Add psql \ev and \sv commands for editing and showing view definitions.

On 3rd of July, Tom Lane committed patch:

Add psql \ev and \sv commands for editing and showing view definitions.
 
These are basically just like the \ef and \sf commands for functions.
 
Petr Korobeinikov, reviewed by Jeevan Chalke, some changes by me

Continue reading Waiting for 9.6 – Add psql \ev and \sv commands for editing and showing view definitions.