Migration to NoSql
DB Migration from SQL DB to NOSQL
(Cassandra) is possible and it is in practice in the real-time. Migration tools
(like DataStax Enterprise) are readily available in the market to migrate data
from SQL to NOSQL DBs
A big reason why many businesses
are moving to NoSQL-based solutions is because
- Legacy
RDBMS data model is not flexible enough to handle big data use cases that
contain a mixture of structured, semi-structured, and unstructured data.
- If
they are planning new applications that are big data in nature and need
something “more” than traditional RDBMS for their database platform.
Though I understand the driving
factors for this DB migration plan is cost, maintainability and performance
Need to ask the business user if
any other factors would impact them as below
- Is
RDBMS currently preventing development of new features?
- Is
NOT providing acceptable uptime?
- Is
NOT scalable for incoming data traffic?
If the decision to migrate to
NOSQL only bcos of Cost and Maintainability, then we are lagging the confident
to say go with NoSQL. Better to stay with RDBMS.
Just summarized the NoSQL
(Cassandra) DB migration plan at very high level as below,
Data Migration
- Export
the data(in JSON file format) into csv or text as per Cassandra table
structure and run CQL query to import into Cassandra
- Otherwise
you may use Sqoop very well to import data directly from RDBMS to
Hadoop-HDFS or NOSQL DB
DB Objects Migration
- Understand
the application behavior and functionalities
- Redesign
the existing whole data model (RDBMS) to Cassandra (query-driven approach
- need to know data access pattern ahead of time), denormalized
- Convert
SQL to Cassandra Queries (CQL) to fetch data for application (may not be
one to one)
- Recreate
the required DB objects which support Cassandra (manually )
FYI, Last year we did work on
SQL Server 2012 to Oracle 12C DB migration, we did follow manual approach to
convert all DB Objects and we had some challenges in syntax conversion and DB
compatible issues in DB objects migration and we did overcome it. This is for
the case RDBMS to RDBMS.
But for RDBMS to Non-relational
like Cassandra would be quite difficult (but it is achievable) and really need
an impact study before proceed.
Attached the article published
on SQL to NoSQL DB migration for your reference.
Also, Please browse the below
link to get a fair idea on this subject.
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