I have a fairly good feel for what MySQL replication can do. I’m wondering what other databases support replication, and how they compare to MySQL and others? Some questions I would have are: Is replication built in, or an add-on/plugin? How does the replication work (high-level)? MySQL provides statement-based replication (and row-based replication in 5.1). … Read more
I created a query that takes a database backup at certain specified location. I want to use it as a stored procedure but this should act as a global stored procedure so that whenever this SP is called. Then database backup is taken. It uses DB_Name() to take database backup of owner database. Is it … Read more
I’ve just installed hadoop and hbase from cloudera (3) but when I try to go to http://localhost:60010 it just sits there continually loading. I can get to the regionserver fine – http://localhost:60030… Looking at the master hbase server logs I can see the following. Looks like a problem with the root region. All of this … Read more
All my classes have an @Version annotation, so I assumed they were using optimistic locking. But I the following exception in my logs that seem to indicate Im using pessimistic locking. So which is it ? (I want to use optimistic locking) update Song set acoustidFingerprint=?, acoustidId=?, album=?, albumArtist=?, albumArtistSort=?, albumSort=?, amazonId=?, arranger=?, artist=?, artistSort=?, … Read more
Given an example of the following select in CQL: SELECT * FROM tickets WHERE ID IN (1,2,3,4) Given ID is a partition key, is using IN relation better than doing multiple queries or is there no difference? Answer I remembered seeing someone answer this question in the Cassandra user mailing list a short while back, … Read more
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 years ago. Improve this question I’m studying Hibernate and JPA, and I am finding this term all the time. Could … Read more
I am studying Cassandra by its document. But when I use “pip install cassandra-driver” to install cassandra-driver ,failed like this: weikairen2@weikairen2-virtual-machine:~$ pip install cassandra-driver Collecting cassandra-driver Using cached cassandra-driver-3.7.0.tar.gz Requirement already satisfied (use –upgrade to upgrade): six>=1.6 in ./.local/lib/python2.7/site-packages (from cassandra-driver) Requirement already satisfied (use –upgrade to upgrade): futures in ./.local/lib/python2.7/site-packages (from cassandra-driver) Building wheels … Read more
How can I drop Foreign keys in general. I mean, if I have many foreign key constraints in a table. like MonthlyEvaluatedBudgetTable Contraints: budgetid_pk (Primary Key) branchid_fk (Foreign Key) accountid_fk (Foreign Key) dept_fk (Foreign Key) Is there a way in postgres to drop all foreign keys in general and not specifically in an existing table? … Read more
I’m changing constraints in my database and I need to drop some of them. I know that for a single constraint, the command is following: ALTER TABLE tblApplication DROP CONSTRAINT constraint1_name; However, when I try ALTER TABLE tblApplication DROP ( CONSTRAINT constraint1_name, CONSTRAINT constraint2_name, CONSTRAINT constraint3_name ); it doesn’t work and I need to do: … Read more
I want to query all products sold in the last 5 years. It is possible to do it like this: select * from products where time between sysdate-1826 and sysdate But it there also a nicer way instead of calculating all the days and subtract it from sysdate? Answer SELECT * FROM products WHERE date_column … Read more
