I want to read data from db using spring jdbctemplate in batches of specific size. I found batchupdate to update table data, but couldn't find any select in batches. Can someone please help me here?
If I understand right what you are looking for then
Use setFetchSize method to set the fetch size. This would select only specific size.
for writing , we call it batch. For reading, we call it paging. in fact, you can implement by yourself. Here is an example.
Related
I need to process millions of records coming from MongoDb and put a ETL pipeline to insert that data into a PostgreSQL database. However, in all the methods I've tried, I keep getting the out memory heap space exception. Here's what I've already tried -
Tried connecting to MongoDB using tMongoDBInput and put a tMap to process the records and output them using a connection to PostgreSQL. tMap could not handle it.
Tried to load the data into a JSON file and then read from the file to PostgreSQL. Data got loaded into JSON file but from there on got the same memory exception.
Tried increasing the RAM for the job in the settings and tried the above two methods again, still no change.
I specifically wanted to know if there's any way to stream this data or process it in batches to counter the memory issue.
Also, I know that there are some components dealing with BulkDataLoad. Could anyone please confirm whether it would be helpful here since I want to process the records before inserting and if yes, point me to the right kind of documentation to get that set up.
Thanks in advance!
As you already tried all the possibilities the only way that I can see to do this requirement is breaking done the job into multiple sub-jobs or going with incremental load based on key columns or date columns, Considering this as a one-time activity for now.
Please let me know if it helps.
My requirement is to do a batch update to a table. I was able to do a Batch insert but could not find a way to do the batch update in Slick3. Any sample or link to a document will be very help full. Tried to search the web could not find a solution. Using Slick 3 on Postgresql.
Why don't you just add whatever data you need to perform to a seq and perform the query. That will do the batching for you. Link here . This applies to all operations not only insert.
Look at this SO question to fall back on standard JDBC and do the update batching.
Also there are some items the team is working on. See here.
In the spring batch program, I am reading the records from a file and comparing with the DB if the data say column1 from file is already exists in table1.
Table1 is fairly small and static. Is there a way I can get all the data from table1 and store it in memory in the spring batch code? Right now for every record in the file, the select query is hitting the DB.
The file is having 3 columns delimited with "|".
The file I am reading is having on an average 12 million records and it is taking around 5 hours to complete the job.
Preload in memory using a StepExecutionListener.beforeStep (or #BeforeStep).
Using this trick data will be loaded once before step execution.
This also works for step restarting.
I'd use caching like a standard web app. Add service caching using Spring's caching abstractions and that should take care of it IMHO.
Load static table in JobExecutionListener.beforeJob(-) and keep this in jobContext and you can access through multiple steps using 'Late Binding of Job and Step Attributes'.
You may refer 5.4 section of this link http://docs.spring.io/spring-batch/reference/html/configureStep.html
My company starts to use mongo and we are starting to think about what is the best way to extract data from mongodb and send it to our data warehouse.
My question focus around the extract part of the process. As i see it, the best way is to expose API on the service that is built on top of mongo, that the ETL process (that is invoked by a job from the data warehouse) will execute with some specific query that will probably will query for set of times (i.e. - startdate and enddate for every record).
is that sound right or i am missing something or maybe there is better way than that?
initially i was thinking about doing mongoexport every X duration but according to the documentation it seems not so good performance wise.
Thanks in advance!
give a try to pentaho kettle.
https://anonymousbi.wordpress.com/2012/07/25/creating-pentaho-reports-from-mongodb/
I am using Alteryx Designer to extract from MongoDB with the dedicated connector and prep my data to load into Tableau, with optional data prep in between.
Works pretty well!
ALteryx can write to most DBs though...
I couldn't use
SQL=TRACE
since, there so many queries executed each second, but wish to see the same result for only one Query.
Is there anyway to get this.
Thanks.
No, there is no way to do this via configuration. Perhaps you could write a custom JDBCListener and try to log only the SQL you care about? Good luck!