Hi All, It has been pointed out that adding another class for handling update / merge queries would not be a good option.
Here are the current implementation details: - We have an existing class: JdbcPOJOOutputOperator which accepts a list of FieldInfo objects. Each element of this list indicates the details (column name, pojo field expression and datatype) of fields that need to be inserted. Using this, the operator formulates the insert query in the setup method and identifies the sql datatypes of these columns from the database using the table name. - Now, coming to the update / merge feature, it is difficult to formulate the update / merge query in the operator logic due to the complex structure of these statements. For this reason, we plan to take a parametrized SQL query from the user. This may look like: *"update table set x = ?, y = ? where z + w > ? and a == 1;"*. Such statements can be accepted from the user in addition to a json string which indicates the details for the parameters: *column name, the pojo expression and the sql data type* of the expression. Note that this information is similar to the FieldInfo object, but is a string which can be configured easily by the user. Also note that the data type which is accepted is the SQL data type. Using this info we can populate the parametrized query and run it based on the incoming POJO. The second approach is able to handle all kinds of queries (insert / update / merge / delete). However, since we already have the JdbcPOJOOutputOperator, we would like to merge the new functionality into the same class. Here we have the following options: 1. Change the existing class (JdbcPOJOOutputOperator) to the second approach which is more generic and also handles inserts. 2. Add the update/ merge functionality to the existing class without changing the existing functionality. This will have two different ways that insert queries may be handled in the operator. 3. Add another class which extends from JdbcPOJOOutputOperator and have the update/merge functionality there. (This is not recommended.) 4. Any other approach. Please suggest. Thanks. -Bhupesh. On Mon, Dec 14, 2015 at 11:04 AM, Chandni Singh <[email protected]> wrote: > No I don't think we are restricting Malhar to just abstract classes. > Whenever they are couple of use cases that we see quite often, we add > concrete implementations. > > For eg. FileLineInputOperator which is a concrete implementation of > AbstractFileInputOperator. FSSliceReader is an example as well. > > In AbstractJdbcOutputOperator case there hasn't been such common > insert/update query. > > Also if you look at the example I provided, it is very simple to provide a > concrete implementation. > > If you would like to change JdbcPOJOOutputOperator to work for > "UPDATE/MERGE" then please go ahead. > > Chandni > > On Sun, Dec 13, 2015 at 8:47 PM, Bhupesh Chawda <[email protected]> > wrote: > > > I see. So, just to understand more, do we plan to keep Malhar restricted > to > > the base functionality (as in abstract classes)? And put the > configuration > > aspect / concrete implementations in apps that use these operators? > > > > Thanks. > > Bhupesh > > > > On Sat, Dec 12, 2015 at 5:43 AM, Chandni Singh <[email protected]> > > wrote: > > > > > Hi, > > > > > > Here is an example of doing Upsert with JDBC: > > > > > > > > > https://github.com/chandnisingh/Malhar/blob/examples/apps/jdbc/src/main/java/com/datatorrent/jdbc/JdbcWriter.java > > > > > > Thanks, > > > Chandni > > > > > > On Fri, Dec 11, 2015 at 11:19 AM, Chandni Singh < > [email protected] > > > > > > wrote: > > > > > > > The operators are under Malhar/lib/db/jdbc. > > > > > > > > Here is one of them: > > > > > > > > > > > > > > https://github.com/apache/incubator-apex-malhar/blob/devel-3/library/src/main/java/com/datatorrent/lib/db/jdbc/AbstractJdbcTransactionableOutputOperator.java > > > > > > > > They work with any kind PreparedStatement - insert or update > > > > > > > > Chandni > > > > > > > > > > > > > > > > On Fri, Dec 11, 2015 at 10:59 AM, Bhupesh Chawda < > > > [email protected]> > > > > wrote: > > > > > > > >> Hi Chandni, > > > >> > > > >> I don't see an update query being handled in the operator. Could you > > > >> please > > > >> point me to the appropriate class? > > > >> Or did you mean that handling a update query is just a matter of > > > extending > > > >> the class and providing a concrete implementation? > > > >> > > > >> Thanks. > > > >> -Bhupesh > > > >> > > > >> On Fri, Dec 11, 2015 at 10:42 PM, Chandni Singh < > > > [email protected]> > > > >> wrote: > > > >> > > > >> > Hi Bhupesh, > > > >> > > > > >> > The current abstract JDBC Output Operators in library are generic > > and > > > >> have > > > >> > already been used in multiple POCs and applications. In fact this > > > >> operator > > > >> > has matured through customer use cases. It is not just an insert > > > >> operator. > > > >> > We have used it to perform update and inserts. > > > >> > > > > >> > That said, I don't think it is a good idea to introduce input > format > > > in > > > >> > these abstract implementations. It is written to handle any type > of > > > >> query, > > > >> > be it a procedure call (that was an actual customer use case). > > > >> > > > > >> > Chandni > > > >> > > > > >> > On Fri, Dec 11, 2015 at 2:50 AM, Bhupesh Chawda < > > > >> [email protected]> > > > >> > wrote: > > > >> > > > > >> > > Hi All, > > > >> > > > > > >> > > We are planning to proceed with the following approach for JDBC > > > >> *update* > > > >> > > operator: > > > >> > > > > > >> > > - *Update Query Configuration* > > > >> > > > > > >> > > > > > >> > > - Example Update Query: *update tableName set a = ?** where b > > = ? > > > >> and > > > >> > c > > > >> > > > ?;* > > > >> > > - Example JSON input array for parameter instantiations: > *[{a, > > > >> > > expression, INTEGER}, {b, expression, VARCHAR}, {c, > expression, > > > >> > DATE}]* > > > >> > > > > > >> > > We are also planning to change the JDBC Output Operator in > Malhar > > > >> Library > > > >> > > which currently does just insert. We plan to make the input > format > > > >> > > consistent for both insert and update and hence the change to > the > > > >> current > > > >> > > way of configuration using JSON. Following would be the config > for > > > >> > inserts: > > > >> > > > > > >> > > - *Insert Query Configuration* > > > >> > > > > > >> > > > > > >> > > - Example Insert Query: *insert into tableName values (?, ?, > > .. , > > > >> ?);* > > > >> > > - Example JSON input array for parameter instantiations: > *[{a, > > > >> > > expression, INTEGER}, {b, expression, VARCHAR}, .. , {c, > > > >> expression, > > > >> > > DATE}]* > > > >> > > > > > >> > > Please let us know your thoughts. > > > >> > > > > > >> > > Thanks. > > > >> > > > > > >> > > -Bhupesh > > > >> > > > > > >> > > > > > >> > > > > > >> > > On Wed, Dec 9, 2015 at 6:38 PM, Bhupesh Chawda < > > > >> [email protected]> > > > >> > > wrote: > > > >> > > > > > >> > > > Hi All, > > > >> > > > > > > >> > > > Would it be a good idea to introduce the update functionality > to > > > the > > > >> > JDBC > > > >> > > > output operator in Apache Apex Malhar library. > > > >> > > > > > > >> > > > The following are possible approaches: > > > >> > > > > > > >> > > > 1. Accept a update query from the user with place holders > for > > > >> > values. > > > >> > > > Example: *update tableName set a = ?, b = ? where c = ? and > > d > > > > >> ?*. > > > >> > > > Here "?" will be provided by the user as java expressions > > which > > > >> will > > > >> > > be > > > >> > > > evaluated from the incoming tuple. > > > >> > > > 2. Another option is to accept in some configuration format > > > >> (json / > > > >> > > > xml) the following and formulate the query in the operator. > > > This > > > >> can > > > >> > > become > > > >> > > > arbitrarily complex. > > > >> > > > 1. update clause columns > > > >> > > > 2. update clause expressions > > > >> > > > 3. where clause columns > > > >> > > > 4. where clause expressions > > > >> > > > > > > >> > > > I am thinking about going ahead with 1. Please let me know if > > any > > > >> other > > > >> > > > option is possible and whether such a functionality already > > exists > > > >> in > > > >> > > some > > > >> > > > other class. > > > >> > > > > > > >> > > > Thanks. > > > >> > > > > > > >> > > > -Bhupesh > > > >> > > > > > > >> > > > > > >> > > > > >> > > > > > > > > > > > > > >
