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Figure out what Tables a JOOQ Function depends on

I was trying to dynamically add some joins to my JOOQ query only when the select statement included fields that required those tables to be part of the query. So I need to know what tables a given Field depends on.
This is easy for TableField's via TableField.getTable().
It looked easy for Function's too - with Function.getArguments() I could recursively walk the function tree until I reached all the TableField leaf nodes.
Sadly for me, however, Function class is package private.
I also didn't see any static utilities in JOOQ that could figure this out for me.
Wonder if there's a way to do this short of dirty regex against generated sql, or sneaky reflection.

The "official" way to do this kind of SQL transformation would be by using the VisitListener SPI and to hook into the query rendering lifecycle, collecting all distinct tables from the SELECT clause, adding them to the FROM clause via the most appropriate join.
This is the only way to get access to the arguments of the internal Function type, short of hacking stuff together via regexes or reflection.
Having said so: Be wary of doing this
You'll need to take care of any of these things (which is probably impossible):
What happens when you self-join a table?
How do you know whether to inner or outer join two tables?
How do you know if you can reuse a table that is already in the FROM clause, or if you have to join it again?
How do you know the "optimal" path from table A to table B if there are several possible ways to join them via foreign key?

Flexible search in database

I have a legacy system that allows users to manage some entities called "TRANSACTION" in the (MySQL) DB, and mapped to Transaction class in Java. Transaction objects have about 30 fields, some of them are columns in the DB, some of them are joins to another tables, like CUSTOMER, PRODUCT, COMPANY and stuff like that.
Users have access to a "Search" screen, where they are allowed to search using a TransactionId and a couple of extra fields, but they want more flexibility. Basically, they want to be able to search using any field in TRANSACTION or any linked table.
I don't know how to make the search both flexible and quick. Is there any way?. I don't think that having an index for every combination of columns is a valid solution, but full table scans are also not valid... is there any reasonable design? I'm using Criteria to build the queries, but this is not the problem.
Also, I think mysql is not using the right indexes, since when I make hibernate log the sql command, I can almost always improve the response time by forcing an index... I'm starting to use something like this trick adapted to Criteria to force a specific index use, but I'm not proud of the "if" chain. I'm getting something like
if(queryDto.getFirstName() != null){
//force index "IDX_TX_BY_FIRSTNAME"
}else if(queryDto.getProduct() != null){
//force index "IDX_TX_BY_PRODUCT"
}
and it feels horrible
Sorry if the question is "too open", I think this is a typical problem, but I can't find a good approach

Hibernate is very good for writing while SQL still excels on reading data. JOOQ might be a better alternative in your case, and since you're using MySQL it's free of charge anyway.
JOOQ is like Criteria on steroids, and you can build more complex queries using the exact syntax you'd use for native querying. You have type-safety and all features your current DB has to offer.
As for indexes, you need can't simply use any field combination. It's better to index the most used ones and try using compound indexes that cover as many use cases as possible. Sometimes the query executor will not use an index because it's faster otherwise, so it's not always a good idea to force the index. What works on your test environment might not stand still for the production system.

Database Search with key words using jpa

I'm doing college work where I have to search by keywords. My entity is called Position and I'm using MySQL. The fields that I need to search are:
    - date
    - positionCode
    - title
    - location
    - status
    - company
    - tecnoArea
I need to search the same word in all of these fields. To this end, I used criteria API to create a dynamic query. It is the same word for several fields and it should get the maximum possible results. Do you have any advice about how to optimize the search on the database. Should I do several queries?
EDIT
I will use an OR constraint.

If you will need to find the key word at any position within the data you will need to use LIKE with wildcards, eg. title LIKE '%manager%'. Since date and positionCode (presumably a numeric type) are not likely to contain the key word, to achieve a very small performance gain, I would omit searching these columns for the key word. Your query is going to need to do a serial read, which means that all rows in the table will need to be brought into main memory to evaluate and retrieve the result set of your query. Given a serial read is going to happen anyway, I do not think there is too much you can do to optimize the query when searching multiple columns. I am not familiar with the "criteria api to create dynamic queries", but using dynamic queries in other systems is non-optimal - they must be parsed and evaluated every time the are run and most query optimize-rs cannot make use of the statistics for cost-based optimization to improve performance like they can with explicitly defined SQL.

Not sure what your database is.
If it is Oracle, you can use Oracle text.
The below link might be useful :
http://swiss-army-development.blogspot.com/2012/02/keyword-search-via-oracle-text.html

Fuzzy Matching in H2 Database?

I was just wondering if there was a simple way to implement Fuzzy matching of strings using the H2 Database.
I have in the database a list of names and I want to be able to search through them using 3 characters that may be found anywere in the name in the order the 3 characters are typed in.
i'm not sure if that's even possible to do, but it would make life much easier if it were possible to be done in the database via SQL and not Java

You could use
select * from test where name like '%xyz%'
See also the documentation of LIKE.
Another option is to use SOUNDEX:
select * from test where soundex(name) = soundex('word')
In both cases, an index can not be used. That means the query is slow if there are many rows in the table, as each row must be checked.

Is HibernateCallback best for executing SQL/procedures?

I'm working on a web based application that belongs to an automobil manufacturer, developed in Spring-Hibernate with MS SQL Server 2005 database.
There are three kind of use cases:
1) Through this application, end users can request for creating a Car, Bus, Truck etc through web based interfaces. When a user logs in, a HTML form gets displayed for capturing technical specification of vehicle, for ex, if someone wanted to request for Car, he can speify the Engine Make/Model, Tire, Chassis details etc and submit the form. I'm using Hibernate here for persistence, i.e. I've a Car Entity that gets saved in DB for each such request.
2) This part of the application deals with generation of reports. These reports mainly dela with number of requests received in a day and the summary. Some of the reports calculate Turnaround time for individual Create vehicle requests.
I'm using plain JDBC calls with Preparedstatement (if report can be generated with SQLs), Callablestatement (if report is complex enough and needs a DB procedure/Function to fetch all details) and HibernateCallback to execute the SQLs/Procedures and display information on screen.
3) Search: This part of application allows ensd users to search for various requests data, i.e. how many vehicle have been requested in a Year etc. I'm using DB procedure with CallableStatement..Once again executing these procedures within HibernateCallback, populating and returning search result on GUI in a POJO.
I'm using native SQL in (2) and (3) above, because for the reporting/search purpose the report data structure to display on screen is not matching with any of my Entity. For ex: Car entity has got more than 100 attributes in itself, but for reporting purpose I don't need more than 10 of them.. so i just though loading all 100 attributes does not make any sense, so why not use plain SQL and retrieve just the data needed for displaying on screen.
Similarly for Search, I had to write procedures/Functions because search algorithm is not straight forward and Hibernate has no way to write a stored procedure kind of thing.
This is working fine for proto type, however I would like to know
a. If my approach for using native SQLs and DB procedures are fine for case 2 and 3 based on my judgement.
b. Also whether executing SQLs in HibernateCallback is correct approach?
Need expert's help.

I would like to know (...) if my approach for using native SQLs and DB procedures are fine for case 2 and 3 based on my judgment
Nothing forces your to use a stored procedure for case 2, you could use HQL and projections as already pointed out:
select f.id, f.firstName from Foo f where ...
Which would return an Object[] or a List<Object[]> depending on the where condition.
And if you want type safe results, you could use a SELECT NEW expression (assuming you're providing the appropriate constructor):
select new Foo(f.id, f.firstName) from Foo f
And you can even return non entities
select new com.acme.LigthFoo(f.id, f.firstName) from Foo f
For case 3, the situation seems different. Just in case, note that the Criteria API is more appropriate than HQL to build dynamic queries. But it looks like this won't help here.
I would like to know (...) whether executing SQLs in HibernateCallback is correct approach?
First of all, there are several restrictions when using stored procedures and I prefer to avoid them when possible. Secondly, if you want to return entities, it isn't the only way and simplest solution as we saw. So for case 2, I would consider using HQL.
For case 3, since you aren't returning entities at all, I would consider not using Hibernate API but the JDBC support from Spring which offers IMHO a cleaner API than Session#connection() and the HibernateCallback.
More interesting readings:
References
Hibernate Core reference guide
14.6. The select clause (about the select new)
16.1.5. Returning non-managed entities (about ResultTransformer)
16.2.2. Using stored procedures for querying
Resources
Hibernate 3.2: Transformers for HQL and SQL
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hibernate SQLquery extract variable
hibernate query language or using criteria

You should strive to use as much HQL as possible, unless you have a good argument (like performance, but do a benchmark first). If the use of native queries becomes to excessive, you should consider whether Hibernate has been a good choice.
Note a few things:
you can have native queries and stored procedures that result in Hibernate entities. You just have to map the query / storproc call to a class and call it by session.createSQLQuery(queryName)
If you really need to construct native queries at runtime, the newest version of hibernate have a doWork(..) method, by which you can do JDBC work.

You say
For ex: Car entity has got more than 100 attributes in itself, but for reporting purpose I don't need more than 10 of them.. so i just though loading all 100 attributes does not make any sense
but HQL in hibernate allows you to do a projection (select only a subset of the columns back). You don't have to pull the entire entity if you don't want to.
Then you get all the benefits of HQL (typing of results, HQL join syntax) but you can pretty much write SQLish code.
See here for the HQL docs and here for the select syntax. If you're used to SQL it's pretty easy.
So to answer you directly
a - No, I think you should be using HQL
b - Becomes irrelevant if you go with my suggestion for a.