FULL join is a combination of the LEFT and RIGHT joins. The LEFT join makes sure that all the records of left table are fetched and RIGHT join makes sure all the records of right hand table are fetched. Thus, in FULL join, the obtained records contain the data from whichever table has ...
Another advantage of NoSQL databases is derived from the freedom that comes with not having to be tied to strict schema. You know that headache where a change to a data model can cause big problems? Well since there is no strict schema with NoSQL – this problem does not exist. This ma...
Every table with a primary key has one clustered index Every table can have many non-clustered indexes to aid in querying Non-clustered indexes hold pointers back to the main table Not every database will benefit from indexing Not every index will increase the query speed for the database ...
When Microsoft came out with their shiny new 2005 SQL server, I decided to implement it in a few installations. Then I went to do a backup and restore at a client site one day because they had a problem with their server. The restore had a message something to the tune of this datab...
Source File: SemiJoinSuite.scala From spark1.52 with Apache License 2.0 5 votes package org.apache.spark.sql.execution.joins import org.apache.spark.sql.{SQLConf, DataFrame, Row} import org.apache.spark.sql.catalyst.planning.ExtractEquiJoinKeys import org.apache.spark.sql.catalyst.plans.Inner ...
The quick notes from many geeks over the internet is a good start and at some instances, the conciseness of the article might meet our requirement; some other cases, it may direct with some pointers. I believe that knowledge sharing is an effective method to grow with mutual terms. Over ti...
No complex joins Structure of asingle object is clear What is the differencebetween SQL and NoSQL? The main differenceis that SQL databases are structured (data is stored in the form of tables with rows and columns - like an excel spreadsheet table) while NoSQL is unstructured, and the...
Let us say you want to count the number of unique values in a given column without doing unnecessary joins and filtering. You can do this using the count() function and passing the DISTINCT clause as the argument. An example usage is as follows: ...
And while this might sound backward to Windows developers, SQL Server on Linux supports the command line interface that Linux geeks prefer. It runs with what Microsoft terms the Platform Abstraction Layer (PAL), which abstracts the core database engine from the opera...
Do not have queries with joins; only query by primary key or index. Do not use sequential primary keys (auto-increment) because they introduce locks. Instead, use client-generated keys, such as GUIDs. Also, when you have master-master replication, auto-increment causes conflicts, so you wil...