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doc: move the TTL Alternator feature from the Experimental Features section to the production-ready section

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Anna Stuchlik
2022-11-16 13:23:07 +01:00
parent d85f731478
commit f1b2f44aad
1 changed files with 29 additions and 18 deletions
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47
docs/alternator/compatibility.md
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@@ -144,6 +144,35 @@ This monitoring stack is different from DynamoDB's offering - but Scylla's
is significantly more powerful and gives the user better insights on
the internals of the database and its performance.
## Time To Live (TTL)
Like in DynamoDB, Alternator items which are set to expire at a certain
time will not disappear exactly at that time, but only after some delay.
DynamoDB guarantees that the expiration delay will be less than 48 hours
(though for small tables the delay is often much shorter).
In Alternator, the expiration delay is configurable - it can it can be be set
with the `--alternator-ttl-period-in-seconds` configuration option.
The default is 24 hours.
<!--- REMOVE IN FUTURE VERSIONS - Remove the note below in version 5.2. -->
---
**NOTE**
In ScyllaDB versions 5.0 and earlier, DynamoDB's TTL feature
is experimental and needs to be enabled explicitly with the
`--experimental-features=alternator-ttl` configuration option.
See [Enabling Experimental Features](#yaml_enabling_experimental_features) for details.
One thing that the experimental implementation is missing is that expiration
events appear in the Streams API as normal deletions - without the
distinctive marker on deletions which are really expirations.
See <https://github.com/scylladb/scylla/issues/5060>.
---
## Experimental API features
Some DynamoDB API features are supported by Alternator, but considered
@@ -158,24 +187,6 @@ individually enabled with the "--experimental-features" configuration option.
In this release, the following DynamoDB API features are considered
experimental:
* DynamoDB's TTL (item expiration) feature is supported, but in this release
still considered experimental and needs to be enabled explicitly with the
`--experimental-features=alternator-ttl` configuration option.
The experimental implementation is mostly complete, but not throughly
tested or optimized.
Like in DynamoDB, Alternator items which are set to expire at a certain
time will not disappear exactly at that time, but only after some delay.
DynamoDB guarantees that the expiration delay will be less than 48 hours
(though for small tables the delay is often much shorter). In Alternator,
the expiration delay is configurable - it defaults to 24 hours but can
be set with the `--alternator-ttl-period-in-seconds` configuration option.
One thing that this implementation is still missing is that expiration
events appear in the Streams API as normal deletions - without the
distinctive marker on deletions which are really expirations.
<https://github.com/scylladb/scylla/issues/5060>
* The DynamoDB Streams API for capturing change is supported, but still
considered experimental so needs to be enabled explicitly with the
`--experimental-features=alternator-streams` configuration option.