I saw that CockroachDB offers JOIN support in this blog post, but it doesn't mention what level of JOINs are supported. Are all of the major types of joins supported, or are there limitations?
CockroachDB supports the major JOIN types:
INNER
FULL OUTER
LEFT
RIGHT
If you need it, you can find the CockroachDB JOIN documentation here.
Related
I have some doubt about "partition wise join", that includes Oracle:
https://www.youtube.com/watch?v=p9BMyQun84Y
Oracle partition-wise join over multiple partitions
I don't understand this functionality. I have watched videos and I still doesn't understand how to use it.
I understand partitioning but I doesn't understand this. I need a simple example.
Thank you.
If you look at the documentation e.g. here, there's a good detailed and lengthy explanation.
I was reading the documentation for SQLC from https://docs.sqlc.dev/en/latest/howto/query_count.html. I wanted to use this in my project. However, I'm not seeing any documentation related to joining operations on the tables. Is it really possible in SQLC. If yes where I could find the documentation or reference?
A commit like "cdf7025: Add MySQL json test" (or "456fcb1 Add MySQL test for SELECT * JOIN") suggests joins are supported.
But it is true, as mentioned in issue 643, that queries with JOINs are for now not documented yet.
I have two transactional tables originating from different databases in different servers. I would like to join them based on common attribute and store the result altogether in different database.
I have been looking for various options in NIFI to execute this as a job which runs monthly.
So far, I have been trying out various options but doesn't seem to work out. For example, I used ExecuteSQL1 & ExecuteSQL2 -> MergeContent-> PutSQL
Could anyone provide pointers on the same?
NiFi is not really meant to do a streaming join like this. The best option would be to implement the join in the SQL query using a single ExecuteSQL processor.
As Bryan said, NiFi doesn't (currently) do this. Perhaps look at Presto, you can set up multiple connections "under the hood" and use its JDBC driver to do what Bryan described, a join across tables in different DBs.
I'm thinking about adding a JoinTables processor that would let you join two tables using two different DBCPConnectionPool controller services, but there are lots of things to consider, such as being able to do the join in memory for example. For joining dimensions to fact tables, we could try to load the smaller table into memory and then we could do more of a streaming join for larger fact tables, for example. Feel free to file a New Feature Jira if you like, and we can discuss there.
Is there anybody knows that anything is not supported by Greenplum Legacy Query optimizer, but supported by Pivotal Query Optimizer?
Thanks a lot!
PQO generate plans that do a better job with partition elimination, and optimizing query common table expressions (WITH Clause). As far SQL support is concerned, Legacy Query Optimizer handles all SQL that GPDB supports. If PQO sees an operation that it does not support, it automatically falls to planner.
The documentation is somewhat misleading when it comes to replicated joins in Pig. The script won't compile if I add 'left' to the join and also using 'replicated'. The documentation mentions only supporting left outer joins with replicated, but the behavior is obviously an inner join. Does anyone know how to do a left replicated join?
c = join a by (x,y,z) left, b by (x,y,z) using 'replicated';
(That statement won't parse)
replicated join can work with either inner or left outer join, and it works for me with 3 fields. what's the error message you're getting? are you sure the fields are of compatible data types? what's your pig version?