catalog: Simplify shard ID generation #30597
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
jkosh44
force-pushed
the
aux-shards
branch
4 times, most recently
from
3d6b161
to
be99cc1
Compare
The catalog has functionality to deterministically generate a random shard ID for a given environment. It used when we need a shard before the catalog is fully opened. It is strictly worse than generating a totally random shard because we limit the amount of randomness. The catalog also has an un-migratable collection called "settings" which maps string keys to string values. This collection is accessible immediately after reading in a snapshot of the catalog, before we finish opening the catalog. Any shard ID used after reading in the snapshot can be generated fully randomly and stored in the settings collection. Two shards fit into this category: - The builtin migration shard. - The expression cache shard. This commit adds a migration to move both those shards to the settings collection for existing environments. New environments will generate the shards randomly and stash the IDs in the settings collection.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The catalog has functionality to deterministically generate a random shard ID for a given environment. It used when we need a shard before the catalog is fully opened. It is strictly worse than generating a totally random shard because we limit the amount of randomness.
The catalog also has an un-migratable collection called "settings" which maps string keys to string values. This collection is accessible immediately after reading in a snapshot of the catalog, before we finish opening the catalog. Any shard ID used after reading in the snapshot can be generated fully randomly and stored in the settings collection.
Two shards fit into this category:
This commit adds a migration to move both those shards to the settings collection for existing environments. New environments will generate the shards randomly and stash the IDs in the settings collection.
Motivation
This PR adds a feature that has not yet been specified.
Checklist
$T ⇔ Proto$Tmapping (possibly in a backwards-incompatible way), then it is tagged with aT-protolabel.