[REVIEW] Re: Re: BUG #9578: Undocumented behaviour for temp tables created inside query language (SQL) functions

(Cc: to pgsql-bugs dropped.)

At 2014-03-17 18:24:55 +1100, kommi.haribabu@gmail.com wrote:
>
> *** a/doc/src/sgml/xfunc.sgml
> --- b/doc/src/sgml/xfunc.sgml
> ***************
> *** 153,159 **** SELECT clean_emp();
> --- 153,186 ----
>       (<literal>\</>) (assuming escape string syntax) in the body of
>       the function (see <xref linkend="sql-syntax-strings">).
>      </para>
> +    
> +    <sect2 id="xfunc-sql-function-parsing-mechanism">
> +     <title>Parsing mechanism of a function</title>
>   
> +    <indexterm>
> +     <primary>function</primary>
> +     <secondary>parsing mechanism</secondary>
> +    </indexterm>

I suggest "Catalog changes within functions" instead of the above title.

> +     <para>
> +      The body of an SQL function is parsed as if it were a single - multi-part
> +      statement and thus uses a constant snapshot of the system catalogs for
> +      every sub-statement therein. Commands that alter the catalog will likely not
> +      work as expected.
> +     </para>
> + 
> +     <para>  
> +      For example: Issuing "CREATE TEMP TABLE" within an SQL function will add
> +      the table to the catalog but subsequent statements in the same function will
> +      not see those additions and thus the temporary table will be invisible to them.
> +     </para>
> + 
> +     <para>  
> +      Thus it is generally advised that <application>PL/pgSQL</> be used, instead of
> +      <acronym>SQL</acronym>, when any catalog visibilities are required in the same function.
> +     </para>
> +    </sect2>

I don't think that much text is warranted. I suggest something like the
following condensed wording:
   <para>    The body of an SQL function is parsed as if it were a single    multi-part statement, using a constant
snapshotof the system    catalogs. The effect of any commands that alter the catalogs    (e.g. "CREATE TEMP TABLE")
willtherefore not be visible to    subsequent commands in the function body.   </para>
 
   <para>    The recommended workaround is to use <application>PL/PgSQL</>.   </para>

Does that seem sensible to you?

-- Abhijit