Hi Flavio,
I have checked the patch into the trunk, so that eliminates one of the
steps. At this point, this is what you need to do:
1) Build the development trunk. The instructions can be found on this
web pages
http://wiki.apache.org/db-derby/ForNewDevelopers
and in particular, here:
http://wiki.apache.org/db-derby/ForNewDevelopers#head-278c37b71407ea38bf6f3310a13d7ebce3e2a32c
2) Compile the ASTParser program
3) Run ASTParser, wiring into the classpath the Derby jars which you
built in step (1).
Please let us know how this works out for you.
Thanks,
-Rick
Flavio Palumbo wrote:
Hi guys,
I followed this post finding it very exciting, cause I post a similar
question a while ago.
Now I'd like to test the work submitted by Rick but I'm not so inside Derby
to catch he whole job I have to do.
I understood that I have to :
- download Derby sources (from where ?)
- apply the patch suggested by Rich (seen the classes but not catch the
lines of code)
- recompile Derby (what libraries/jars I need to)
- use ASTParser as suggested
Can somebody give me a hint ?
Thanks a lot
Flavio
-----Messaggio originale-----
Da: news [mailto:[EMAIL PROTECTED] conto di Christian Riedel
Inviato: giovedì 13 novembre 2008 6.37
A: [email protected]
Oggetto: Re: Using derby to parse an SQL statement
Hi Rick,
at first thank you very much for your efforts so far. At a first glance
your changes to the code seem to be exactly what we want. I will try if
it works asap.
To test it with the derby libs I'd have to work on the current trunk and
apply the patch an then compile derby manually, right?
I'll keep you updated
Thanks for your help
Christian
Rick Hillegas schrieb:
Hi Christian,
I have created a JIRA to track this issue:
https://issues.apache.org/jira/browse/DERBY-3946
I have attached to the JIRA a small patch which exposes the AST
produced
by the parser. I have also attached a simple program, ASTParser, which
shows how to retrieve the AST from Derby. I am inclined to check this
patch in to the trunk. Please let me know if you find this
useful and if
you would like me to port this patch to another Derby branch.
Hope this helps,
-Rick
Christian Riedel wrote:
Hi Rick,
first of all thanks for your answer ... now the relations have become
a lot clearer ...
Your are right, there is a lot of things to be done that we probably
don't want to go through. You asked why we cannot take the whole derby
engine and use it ... well there is nor real reason not to do so. The
only "problem" I see is, that derby is a dbms - if I am not mistaken -
and we only have an SQL statement that we extract from a text file and
want tot analyze it to extract some metadata from it.
So if we take the derby engine as it is, how can I prevent that we
have to set up a "dummy" DB in order to be able to actually use thje
parsing feature ....
I hope you see my point.
We could live with setting up a dummy DB ... and I do think that the
derby AST offers all information we need. It's just that I don't see
how we can set this thing up. So having a dummy DB is necessary to be
able to intercept the parsing process to get hold of the AST? Can we
actually access the AST if we choose to set up a dummy DB? I think
that would be something we could live with ;-)
Thanks for your support
Christian
Rick Hillegas schrieb:
Hi Christian,
I think you will have difficulty isolating the Parser from the rest
of the SQL interpreter. In theory, you should be able to isolate the
compiler from the execution engine and the storage layer--but that is
an untested theory.
The Parser wants to turn out abstract syntax trees (AST). Ideally,
the Parser would just need to ask a NodeFactory for AST nodes and you
could supply your own NodeFactory. But I think that there is a fair
amount of coupling between the Parser and Derby's concrete
implementation of NodeFactory. I think that you could uncouple the
two, but you may not want to spend your time on that.
So the Parser is going to force you to pull in the AST nodes. Once
you do that, you will end up with the whole compiler. In particular,
the AST nodes (and the Parser itself) expect that you will supply an
implementation of LanguageConnectionContext, the master state
variable for the whole SQL interpreter. Untangling that requirement
is another chunk of work you may not want to do.
Then there is the Monitor. It has been a while since I was in that
code but I seem to recall that fairly early on the Monitor wants to
fault in a storage layer. In theory you ought to be able to supply
the Monitor a list of modules that doesn't include a storage layer.
But since no-one runs in this configuration, there are probably a lot
of undocumented surprises that you may not want to fix either.
Can I ask you what breaks if you just pull in the whole Derby engine?
Are you concerned that you will fault in too much code that you
barely use? Are you concerned that you'll end up with a dummy
database that you don't need? Are Derby's AST nodes not a usable
representation of statement syntax?
Thanks,
-Rick
Christian Riedel wrote:
Hi there,
we are working on a small project where we need to analyze an SQL
statement that can be of any kind: very simple, with inner selects,
complex join etc.
We figured it inappropriate to start to write our own parser when
there are other projects, like derby, out there that can do it much
better than we would possibly do ... so this was our idea:
Can we use derby to create an instance of Parser
(org.apache.derby.iapi.sql.compile.Parser.class) and let our SQL
statement be parsed by calling the parse() method on this instance?
What we want to have is a syntax tree of the statement that allows
us to see which tables and which fields are accessed / included in
the statement (including any possibly done "renames" á la SELECT
street AS "ADDRESS" FROM USER_DATA ).
The problem is, that we are stuck ... we spent several days now to
try to find the proper way to create an instance of the Parser. Is
it possible at all without having to set up a running derby system?
Is the Monitor class the right entry point? How can we create a
CompilerContext so that a Parser instance can be created?
This sure is off-topic but we don't see any way through all this.
Can you help us?
Thanks in advance
Christian
--
To reply to this posting directly use the following address and
remove the 'NO-SPAM' part: [EMAIL PROTECTED]
-----------------------------------------------------------
Il presente messaggio non costituisce un impegno contrattuale tra SILMA S.r.l.
ed il destinatario.
Le opinioni ivi espresse sono quelle dell'autore.
SILMA S.r.l. non assume alcuna responsabilita riguardo al contenuto del
presente messaggio.
Il messaggio è destinato esclusivamente al destinatario.
Il contenuto e gli allegati sono da considerarsi di natura confidenziale
Nel caso abbiate ricevuto il presente messaggio per errore siete pregati di
comunicarlo
alla casella [EMAIL PROTECTED]
