From f1b2f44aad8a577d5a41db98ef69551dda09d64f Mon Sep 17 00:00:00 2001 From: Anna Stuchlik Date: Wed, 16 Nov 2022 13:23:07 +0100 Subject: [PATCH] doc: move the TTL Alternator feature from the Experimental Features section to the production-ready section --- docs/alternator/compatibility.md | 47 ++++++++++++++++++++------------ 1 file changed, 29 insertions(+), 18 deletions(-) diff --git a/docs/alternator/compatibility.md b/docs/alternator/compatibility.md index 9db834e125..bb41bfcd56 100644 --- a/docs/alternator/compatibility.md +++ b/docs/alternator/compatibility.md @@ -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. + + +--- + +**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 . + +--- + + ## 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. - - * 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.