Re: [RFC] nodeToString format and exporting the SQL parser - Mailing list pgsql-hackers

2010/4/21 Jehan-Guillaume (ioguix) de Rorthais <ioguix@free.fr>:
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> On 04/04/2010 18:10, David Fetter wrote:
>> On Sat, Apr 03, 2010 at 03:17:30PM +0200, Markus Schiltknecht wrote:
>>> Hi,
>>>
>>> Michael Tharp wrote:
>>>> I have been spending a little time making the internal SQL parser
>>>> available to clients via a C-language SQL function.
>>>
>>> This sounds very much like one of the Cluster Features:
>>> http://wiki.postgresql.org/wiki/ClusterFeatures#API_into_the_Parser_.2F_Parser_as_an_independent_module
>>>
>>> Is this what you (or David) have in mind?
>>
>> I'm not a fan of statement-based replication of any description.  The
>> use cases I have in mind involve things like known-correct syntax
>> highlighting in text editors.
>
> The point here is not to expose the internal data structure, but to
> deliver a tokenized version of the given SQL script.
>
> There's actually many different use cases for external projects :
>  - syntax highlighting
>  - rewrite query with proper indentation
>  - replication
>  - properly splitting queries from a script
>  - define type of the query (SELECT ? UPDATE/DELETE ? DDL ?)
>  - checking validity of a query before sending it
>  - ...
>
> In addition of PgPool needs, I can see 3 or 4 direct use cases for
> pgAdmin and phpPgAdmin.
>
> So it seems to me having the parser code in a shared library would be
> very useful for external C projects which can link to it. However it
> would be useless for other non-C projects which can't use it directly
> but are connected to a PostgreSQL backend anyway (phpPgAdmin as instance).
>
> What about having a new SQL command like TOKENIZE ? it would kinda act
> like EXPLAIN but giving a tokenized version of the given SQL script. As
> EXPLAIN, it could speak XML, YAML, JSON, you name it...
>
> Each token could have :
>  - a type ('identifier', 'string', 'sql command', 'sql keyword',
> 'variable'...)
>  - the start position in the string
>  - the value
>  - the line number
>  - ...
>
> A simple example of a tokenizer is the php one:
>  http://fr.php.net/token_get_all
>
> And here is a basic example which return pseudo rows here :
>
> => TOKENIZE $script$
>    SELECT 1;
>    UPDATE test SET "a"=2;
>  $script$;
>

you don't need special command for this task .. function is enough

new SQL command is useless

http://www.pgsql.cz/index.php/Oracle_functionality_%28en%29#PLVlex

it can be very simple with new changes in parser.

Regards
Pavel Stehule



>   type      | pos |   value  | line
> - -------------+-----+----------+------
>  SQL_COMMAND | 1   | 'SELECT' |   1
>  CONSTANT    | 8   | '1'      |   1
>  DELIMITER   | 9   | ';'      |   1
>  SQL_COMMAND | 11  | 'UPDATE' |   2
>  IDENTIFIER  | 18  | 'test'   |   2
>  SQL_KEYWORD | 23  | 'SET'    |   2
>  IDENTIFIER  | 27  | '"a"'    |   2
>  OPERATOR    | 30  | '='      |   2
>  CONSTANT    | 31  | '1'      |   2
>
>>
>> Cheers,
>> David.
>
> As a phpPgAdmin dev, I am thinking about this subject since a long time.
> I am interested about trying to create such a patch after discussing it
> and if you think it is doable.
>
> - --
> JGuillaume (ioguix) de Rorthais
> http://www.dalibo.com
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