DistOS 2015W Session 11: Difference between revisions
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== Dynamo== | == Dynamo== | ||
* Amazon's Key Value Store | |||
*Availability is the buzz word for Dynamo. Dynamo=Availability | *Availability is the buzz word for Dynamo. Dynamo=Availability | ||
*Shifted Computer Science paradigm from caring about the consistency to availability. | *Shifted Computer Science paradigm from caring about the consistency to availability. | ||
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*Treats failure handling as normal case without impact on availability and performance. | *Treats failure handling as normal case without impact on availability and performance. | ||
*Data is partitioned and replicated using consistent hashing and consistency is facilitated by use of object versioning. | *Data is partitioned and replicated using consistent hashing and consistency is facilitated by use of object versioning. | ||
* This system has certain requirements such as: | |||
** Query Model: Simple read and write operations to data item that are uniquely identified by a key. | |||
**ACID properties: Atomicity, Consistency, Isolation, Durability. | |||
**Efficiency: System needs to function on a commodity hardware infrastructure. | |||
* The system consists of Service Level Agreements(SLA), which is a negotiated contract between a client and a service regarding characteristics related to systems. They are used in order to guarantee that in a bounded time period, an application can deliver it's functionality. | |||
==Cassandra== | ==Cassandra== | ||
Revision as of 23:18, 30 March 2015
BigTable
- Google System used for storing data of various Google Products, for instance Google Analytics, Google Finance, Orkut, Personalized Search, Writely, Google Earth and many more
- Big table is
- Sparse
- Persistant
- Muti dimensional Sorted Map
- It is indexed by
- Row Key: Every read or write of data under single row key is atomic. Each row range is called Tablet. Select Row key to get good locality for data access.
- Column Key: Grouped into sets called Column Families. Forms basic unit of Access Control.All data stored is of same type.Syntax used: family:qualifier
- Time Stamp:Each cell consists of multiple versions of same data which are indexed by Timestamps.In order to avoid collisions, Timestamps need to be generated by applications.
- Big Table API: Provides functions for
- Creating and Deleting
- Tables
- Column Families
- Changing Cluster
- Changing Table
- Column Family metadata like Access Control Rights.
- Set of wrappers which allow Big Data to be used both as
- Input source
- Output Target
- Creating and Deleting
Dynamo
- Amazon's Key Value Store
- Availability is the buzz word for Dynamo. Dynamo=Availability
- Shifted Computer Science paradigm from caring about the consistency to availability.
- Sacrifices consistency under certain failure scenarios.
- Treats failure handling as normal case without impact on availability and performance.
- Data is partitioned and replicated using consistent hashing and consistency is facilitated by use of object versioning.
- This system has certain requirements such as:
- Query Model: Simple read and write operations to data item that are uniquely identified by a key.
- ACID properties: Atomicity, Consistency, Isolation, Durability.
- Efficiency: System needs to function on a commodity hardware infrastructure.
- The system consists of Service Level Agreements(SLA), which is a negotiated contract between a client and a service regarding characteristics related to systems. They are used in order to guarantee that in a bounded time period, an application can deliver it's functionality.
Cassandra
- Partitions data across the cluster using consistent hashing.
Spanner
- Provided data consistency and Supports SQL like Interface