Re: SQL-spec incompatibilities in similar_escape() and related stuff

On 2019-May-23, Tom Lane wrote:

> +   <para>
> +    Another nonstandard extension is that following the escape character
> +    with a letter or digit provides access to the same escape sequences
> +    defined for POSIX regular expressions, below (see
> +    <xref linkend="posix-character-entry-escapes-table"/>,
> +    <xref linkend="posix-class-shorthand-escapes-table"/>, and
> +    <xref linkend="posix-constraint-escapes-table"/>).
>     </para>

I think the word "same" in this para is more confusing than helpful;
also the tables are an integral part of this rather than just an
illustration, so they should not be in parenthesis but after only a
semicolon or such.  So:

> +    Another nonstandard extension is that following the escape character
> +    with a letter or digit provides access to the escape sequences
> +    defined for POSIX regular expressions; see
> +    <xref linkend="posix-character-entry-escapes-table"/>,
> +    <xref linkend="posix-class-shorthand-escapes-table"/>, and
> +    <xref linkend="posix-constraint-escapes-table"/> below.

I think it would be useful to provide a trivial example that illustrates
this in the <para> below; say '\mabc\M' not matching "zabc".

All in all, these are pretty trivial points and I would certainly not be
mad if it's committed without these changes.

Marked ready for committer.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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