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Amazon RDS vs Lambda (AWS Serverless)

Amazon RDS logo

Amazon RDS

Software

Set up, operate, and scale a relational database in the cloud

From
On request
Rated
-
Full reviewWebsite
Lambda (AWS Serverless) logo

Lambda (AWS Serverless)

Software

Run code without thinking about servers

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Lambda (AWS Serverless) has a free tier, so it costs nothing to try first.
  • Each has a real cost: Amazon RDS no super-user access or direct host connectivity limits advanced customization; Lambda (AWS Serverless) billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does
  • They diverge on capability: Amazon RDS covers Multiple DB Engines, Lambda (AWS Serverless) covers Function-as-a-Service.

Where they differ

Only the attributes on which Amazon RDS and Lambda (AWS Serverless) actually diverge.

Attributes where Amazon RDS and Lambda (AWS Serverless) differ
AttributeAmazon RDSLambda (AWS Serverless)
Starting priceOn requestFree
Pricing modelUnknownusage-based
Free tierNoYes
PlatformsAWS Cloud, Multi-AZ, Multi-regionWeb, Api
Founded20062014

Identical on both: user rating (Not yet rated), category (Unknown).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Amazon RDS

  • Multiple DB Engines
  • Automated Backups
  • Multi-AZ Deployment
  • Read Replicas
  • Performance Insights
  • Automatic Scaling
  • MySQL
  • PostgreSQL

Only in Lambda (AWS Serverless)

  • Function-as-a-Service
  • Event-driven execution
  • Auto-scaling
  • Pay-per-use
  • Multiple languages
  • Concurrency limits
  • Dead Letter Queues
  • Environment variables

Both cover

  • Encryption
  • Web support

What people use each for

The jobs each tool is most often brought in to do.

Amazon RDS

  • Transaction processingnot Lambda (AWS Serverless)
  • Data storagenot Lambda (AWS Serverless)
  • Application backendnot Lambda (AWS Serverless)
  • Reportingnot Lambda (AWS Serverless)
  • Data analyticsnot Lambda (AWS Serverless)

Lambda (AWS Serverless)

  • Event-driven functions without managing serversnot Amazon RDS
  • API backends behind API Gatewaynot Amazon RDS
  • Processing S3, DynamoDB, SQS and Kinesis eventsnot Amazon RDS
  • Scheduled jobs without a always-on instancenot Amazon RDS
  • Edge compute through Lambda@Edgenot Amazon RDS

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Amazon RDS

  • No super-user access or direct host connectivity limits advanced customization
  • Pricing unpredictable and expensive compared to GCP alternatives with equivalent features
  • Limited access to system procedures and tables requiring advanced permissions
  • No Oracle RAC (Real Application Clusters) support for high-availability Oracle deployments

Lambda (AWS Serverless)

  • Billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does
  • Provisioned concurrency, used to avoid cold starts, is charged separately at $0.0000041667 per GB-second whether or not the function runs
  • Ephemeral storage beyond the included 512 MB is metered
  • Lambda@Edge costs $0.60 per million requests, three times the standard request rate
  • VPC use and cross-region data transfer carry EC2 charges on top

Pricing, plan by plan

Amazon RDS

On request

No published plan breakdown. See the Amazon RDS review.

Lambda (AWS Serverless)

Free
  • Free TierFree
    • 1M free requests/month
    • 400,000 GB-seconds/month
    • Always free

Which should you pick?

Choose Amazon RDS if

  • You need multiple db engines.
  • You work on AWS Cloud, Multi-AZ, Multi-region.
  • You also want automated backups.
Amazon RDS review

Choose Lambda (AWS Serverless) if

  • You need function-as-a-service.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want event-driven execution.
Lambda (AWS Serverless) review

Questions people ask

Is Amazon RDS or Lambda (AWS Serverless) better?
Neither clearly leads. Amazon RDS starts at On request and Lambda (AWS Serverless) at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Amazon RDS or Lambda (AWS Serverless)?
Lambda (AWS Serverless) has a free tier; the other does not. Paid plans start at On request for Amazon RDS and Free for Lambda (AWS Serverless).
Does Amazon RDS or Lambda (AWS Serverless) run on more platforms?
Amazon RDS runs on AWS Cloud, Multi-AZ, Multi-region. Lambda (AWS Serverless) runs on Web, Api.
Can I use Lambda (AWS Serverless) for free?
Yes. Lambda (AWS Serverless) has a free tier, so you can try it without paying. Amazon RDS starts at On request.
What is Amazon RDS best used for?
Amazon RDS is most often used for transaction processing, data storage, application backend, reporting. Of those, transaction processing and data storage are not what Lambda (AWS Serverless) is typically brought in for.
What can Amazon RDS do that Lambda (AWS Serverless) cannot?
Amazon RDS covers Multiple DB Engines, Automated Backups, Multi-AZ Deployment, Read Replicas. Lambda (AWS Serverless) covers Function-as-a-Service, Event-driven execution, Auto-scaling, Pay-per-use. Both handle Encryption, Web support.

Answered from the vendors’ own pages

Amazon RDS: What databases does Amazon RDS support?

Amazon RDS supports Amazon Aurora, PostgreSQL, MySQL, MariaDB, Oracle Database, and Microsoft SQL Server as managed database engines.

Source
Amazon RDS: Does Amazon RDS handle backups automatically?

Yes. Amazon RDS automates backup configuration, backing up your database and transaction logs. Blue/Green Deployments allow safer updates by mirroring production in staging before applying changes.

Source
Amazon RDS: How does Amazon RDS Proxy improve performance?

Amazon RDS Proxy is a managed database proxy that makes applications more scalable by reducing database connection overhead, more resilient to database failures, and more secure through built-in authentication.

Source
Amazon RDS: Does Amazon RDS provide read replicas?

Yes. Amazon RDS supports read replicas across availability zones and regions, enabling horizontal scaling of read capacity while maintaining a single write primary.

Source
Amazon RDS: Can I access the host directly via SSH or Remote Desktop?

No. Amazon RDS does not allow direct host access via SSH, Telnet, or Windows Remote Desktop Connection. Database access is limited to database clients and management console.

Source
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