Re: proposal - assign result of query to psql variable - Mailing list pgsql-hackers

From Pavel Stehule
Subject Re: proposal - assign result of query to psql variable
Date
Msg-id CAFj8pRCk9c_oAR=-RXBkD38f8-PU7GufjL3zQiKY7SQzQcKt_A@mail.gmail.com
Whole thread Raw
In response to Re: proposal - assign result of query to psql variable  (Shigeru HANADA <shigeru.hanada@gmail.com>)
Responses Re: proposal - assign result of query to psql variable  (Phil Sorber <phil@omniti.com>)
List pgsql-hackers
2012/10/16 Shigeru HANADA <shigeru.hanada@gmail.com>:
> Hi Pavel,
>
> On Tue, Oct 16, 2012 at 6:59 AM, Pavel Stehule <pavel.stehule@gmail.com>
> wrote:
>> here is updated patch, I moved lot of code from lexer to command.com,
>> and now more \gset doesn't disable other backslash commands on same
>> line.
>
> * lexer changes
> IIUC, new function psql_scan_varlist_varname scans input and returns a
> variable name or a comma at each call, and command.c handles the error
> such as invalid # of variables.  This new design seems better than old one.
>
> However, IMHO the name psql_scan_varlist_varname sounds redundant and
> unintuitive.  I'd prefer psql_scan_slash_varlist, because it indicates
> that that function is expected to be used for arguments of backslash
> commands, like psql_scan_slash_command and psql_scan_slash_option.
> Thoughts?
>
> * multiple meta command
> Now both of the command sequences
>
>   $ SELECT 1, 2 \gset var1, var2 \g foo.txt
>   $ SELECT 1, 2 \g foo.txt \gset var1, var2
>
> set var1 and v2 to "1" and "2" respectively, and also write the result
> into foo.txt.  This would be what users expected.
>
> * Duplication of variables
> I found an issue we have not discussed.  Currently \gset accepts same
> variable names in the list, and stores last SELECT item in duplicated
> variables.  For instance,
>
>   $ SELECT 1, 2 \gset var, var
>
> stores "2" into var.  I think this behavior is acceptable, but it might
> be worth mentioning in document.
>
> * extra fixes
> I fixed some minor issues below.  Please see attached v10 patch for details.
>
>   * remove unused macro OT_VARLIST
>   * remove unnecessary #include directive for common.h
>   * fill comment within 80 columns
>   * indent short variable name with tab
>   * add regression test case for combination of \g and \gset
>
> * bug on FETCH_COUNT = 1
> When FETCH_COUNT is set to 1, and the number of rows returned is 1 too,
> \gset shows extra "(1 row)".  This would be a bug in
> ExecQueryUsingCursor.  Please see the last test case in regression test
> psql_cmd.

I fixed this bug

Regards

Pavel

>
> I'll mark this patch as "waiting author".
>
> Regards,
> --
> Shigeru HANADA

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