## Description
There is a bug in the metadata defaults code, see [the original PR](https://github.com/hasura/graphql-engine-mono/pull/6286).
Steps to reproduce this issue:
* Start a new HGE project
* Start HGE with a defaults argument: `HASURA_GRAPHQL_LOG_LEVEL=debug cabal run exe:graphql-engine -- serve --enable-console --console-assets-dir=./console/static/dist --metadata-defaults='{"backend_configs": {"dataconnector": {"mongo": {"display_name": "BONGOBB", "uri": "http://localhost:8123"}}}}'`
* Add a source (doesn't need to be related to the defaults)
* Export metadata
* See that the defaults are present in the exported metadata
## Related Issues
* Github Issue: https://github.com/hasura/graphql-engine/issues/9237
* Jira: https://hasurahq.atlassian.net/browse/GDC-647
* Original PR: https://github.com/hasura/graphql-engine-mono/pull/6286
## Solution
* The test for if defaults should be included for metadata api operations has been extended to check for updates
* Metadata inconsistencies have been hidden for `/capabilities` calls on startup
## TODO
* [x] Fix bug
* [x] Write tests
* [x] OSS Metadata Migration to correct persisted data - `server/src-rsr/migrations/47_to_48.sql`
* [x] Cloud Metadata Migration - `pro/server/res/cloud/migrations/6_to_7.sql`
* [x] Bump Catalog Version - `server/src-rsr/catalog_version.txt`
* [x] Update Catalog Versions - `server/src-rsr/catalog_versions.txt` (This will be done by Infra when creating a release)
* [x] Log connection error as it occurs *(Already being logged. Requires `--enabled-log-types startup,webhook-log,websocket-log,http-log,data-connector-log`)
* [x] Don't mark metadata inconsistencies for this call.
## Questions
* [ ] Does the `pro/server/res/cloud/migrations/6_to_7.sql` cover the cloud scenarios?
* [ ] Should we have `SET search_path` in migrations?
* [x] What should be in `server/src-rsr/catalog_versions.txt`?
## Testing
To test the solution locally run:
> docker compose up -d
and
> cabal run -- exe:api-tests --skip BigQuery --skip SQLServer --skip '/Test.API.Explain/Postgres/'
## Solution
In `runMetadataQuery` in `server/src-lib/Hasura/Server/API/Metadata.hs`:
```diff
- if (exportsMetadata _rqlMetadata)
+ if (exportsMetadata _rqlMetadata || queryModifiesMetadata _rqlMetadata)
```
This ensures that defaults aren't present in operations that serialise metadata.
Note: You might think that `X_add_source` would need the defaults to be present to add a source that references the defaults, but since the resolution occurs in the schema-cache building phase, the defaults can be excluded for the metadata modifications required for `X_add_source`.
In addition to the code-change, a metadata migration has been introduced in order to clean up serialised defaults.
The following scenarios need to be considered for both OSS and Cloud:
* The user has not had defaults serialised
* The user has had the defaults serialised and no other backends configured
* The user has had the defaults serialised and has also configured other backends
We want to remove as much of the metadata as possible without any user-specified data and this should be reflected in migration `server/src-rsr/migrations/47_to_48.sql`.
## Server checklist
### Catalog upgrade
Does this PR change Hasura Catalog version?
- ✅ Yes
### Metadata
Does this PR add a new Metadata feature?
- ✅ No
### GraphQL
- ✅ No new GraphQL schema is generated
### Breaking changes
- ✅ No Breaking changes
## Changelog
__Component__ : server
__Type__: bugfix
__Product__: community-edition
### Short Changelog
Fixes a metadata defaults serialization bug and introduces a metadata migration to correct data that has been persisted due to the bug.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/7034
GitOrigin-RevId: ad7d4f748397a1a607f2c0c886bf0fbbc3f873f2
Modifying schema-sync implementation to use polling for OSS/Pro. Invalidations are now propagated via the `hdb_catalog.hdb_schema_notifications` table in OSS/Pro. Pattern followed is now a Listener/Processor split with Cloud listening for changes via a LISTEN/NOTIFY channel and OSS polling for resource version changes in the metadata table. See issue #460 for more details.
GitOrigin-RevId: 48434426df02e006f4ec328c0d5cd5b30183db25
Add optimistic concurrency control to the ‘replace_metadata’ call.
Prevents users from submitting out-of-date metadata to metadata-mutating APIs.
See https://github.com/hasura/graphql-engine-mono/issues/472 for details.
GitOrigin-RevId: 5f220f347a3eba288a9098b01e9913ffd7e38166
* Test working through a backlog of change events
* Use a slightly more performant threaded http server in eventing pytests
This helped locally but not on CI it seems...
* Rework event processing for backpressure. Closes#3839
With loo low `HASURA_GRAPHQL_EVENTS_FETCH_INTERVAL` and/or slow webhooks
and/or too small `HASURA_GRAPHQL_EVENTS_HTTP_POOL_SIZE` we might
previously check out events from the DB faster than we can service them,
leading to space leaks, weirdness, etc.
Other changes:
- avoid fetch interval sleep latency when we previously did a non-empty
fetch
- prefetch event batch while http pool is working
- warn when it appears we can't keep up with events being generated
- make some effort to process events in creation order so we don't
starve older ones.
ALSO NOTE: HASURA_GRAPHQL_EVENTS_FETCH_INTERVAL changes semantics
slightly, since it only comes into play after an empty fetch. The old
semantics weren't documented in detail, so I think this is fine.
