Re: [HACKERS] Flexible configuration for full-text search

Hi Arthur,

Thank you for the review.

On Thu, 21 Dec 2017 17:46:42 +0300
Arthur Zakirov <a.zakirov@postgrespro.ru> wrote:

> I noticed that there are typos in the documentation. And I think it
> is necessary to keep information about previous sintax. The syntax
> will be supported anyway. For example, information about TSL_FILTER
> was removed. And it will be good to add more examples of the new
> syntax.

In the current version of the patch, configurations written in old
syntax are rewritten into the same configuration in the new syntax.
Since new syntax doesn't support a TSL_FILTER, it was removed from the
documentation. It is possible to store configurations written in old
syntax in a special way and simulate a TSL_FILTER behavior for them.
But it will lead to maintenance of two different behavior of the FTS
depends on a version of the syntax used during configuration. Do you
think we should keep both behaviors?

> The result of ts_debug() function was changed. Is it possible to keep
> the old ts_debug() result? To be specific, 'dictionaries' column is
> text now, not array, as I understood. It will be good to keep the
> result for the sake of backward compatibility.

Columns' 'dictionaries' and 'dictionary' type were changed to text
because after the patch the configuration may be not a plain array of
dictionaries but a complex expression tree. In the column
'dictionaries' the result is textual representation of configuration
and it is the same as a result of \dF+ description of the configuration.

I decide to rename newly added column to 'configuration' and keep
column 'dictionaries' with an array of all dictionaries used in
configuration (no matter how). Also, I fixed a bug in 'command' output
of the ts_debug in some cases.

Additionally, I added some examples to documentation regarding
multilingual search and combination of exact and linguistic-aware
search and fixed typos.