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FastEndpoints.OData is ninety lines that bolt Microsoft's OData query engine onto a REPR endpoint - a sealed Configure(), a fake ParameterInfo, and an endpoint filter that fishes the response out of HttpContext.Items. Reading it is a masterclass in integrating with a framework through its narrowest seam. Part 7 of FastEndpoints — The Missing Chapters.
Nine parts of architecture posts lie by omission unless the tenth is the ledger. What earned its keep — isolation as data, MaxTenants = 1, the schema-keyed model cache — and the honest list of shortcuts: plaintext connection strings, cache windows, reflection, and a fan-out loop that still says TODO.
The read side of archive-on-delete: querying archives through promoted typed columns, digging into jsonb payloads for everything else, polling snapshots with a 202 pattern, and an honest accounting of the restore path ArchiveKit doesn't have yet. Part 9 wraps up the Archive-on-Delete with ArchiveKit series.
Archive tables are meant to empty out - a background worker migrates their rows into the current table while live traffic reads and write-through updates race it. This part walks the EF backfill's insert-then-conditional-delete choreography and the timestamp that keeps it honest. Part 9 of the Entity Versioning with VersionKit series.
Retention as a first-class column: how ArchiveKit stamps ExpiresAt at archive time from a TtlDays attribute, hard-deletes expired rows in bounded batches, and runs the whole thing on Lambda with the hosted services switched off. Also, the rows TTL doesn't clean yet. Part 8 of the Archive-on-Delete with ArchiveKit series.
A point lookup that might hit any of three tables, a list query that should span them all, and writes that must keep a registry honest - this part walks VersionKit's version-aware reader and writer, and the generated UNION view that makes every schema era queryable as if it were current. Part 8 of the Entity Versioning with VersionKit series.
Shipping a migration to one database is a deploy step. Shipping it to every schema in every group database is an orchestration problem — cross-database MigrateAsync, an HTTP migration surface, a per-tenant audit ledger, and the honest gap where the fan-out loop should be.
ArchiveKit's snapshot service assembles a full JSON tree of a deleted object graph using nothing but archive rows - the primary data is already gone. Job tickets, a four-state machine, retries with a terminal Failed state, and the single-table assembly limitation I still owe a fix for. Part 7 of the Archive-on-Delete with ArchiveKit series.
JSON payloads can migrate lazily because the reader controls the shape - relational rows cannot, because the table is the shape. VersionKit's EF Core answer is table-per-version - archive Orders as Orders_v2 on a schema bump, track every row's home in a registry, and let old rows stay old until something moves them. Part 7 of the Entity Versioning with VersionKit series.
Deleting a tenant is the most dangerous button in the platform — behind it sit DROP SCHEMA CASCADE and DROP DATABASE. A two-step lifecycle with global query filters, a SaveChanges interception and an explicit purge keeps the blast radius survivable.
Correlation ids and cascade archiving in ArchiveKit - how one Guid per save turns scattered archive rows into a reconstructable object graph, why cascade happens through the EF change tracker rather than the database, and two honest limits: a naive root heuristic and a CascadeArchive flag the interceptor doesn't read yet. Part 6 of the Archive-on-Delete with ArchiveKit series.
Tenants are data too. The tenant-management database is the one single-tenant database in the whole platform, and its five entities — Tenant, TenantConnection, TenantFeature, DatabaseGroup, TenantMigrationHistory — carry every decision the rest of the series depends on.
How ArchiveKit wires itself up - the [Archivable] attribute's three knobs, an assembly scanner that fails fast at startup instead of quietly at delete time, the static registry behind every lookup, and the AddArchiveKit configuration surface. Plus an honest note about the source generator that doesn't exist yet. Part 5 of the Archive-on-Delete with ArchiveKit series.
A signup click becomes a real PostgreSQL database or schema in seconds. Running CREATE DATABASE from application code feels illegal until you contain it — identifier validation, quoted DDL, idempotent steps, and a status machine that admits when provisioning fails.
The storage design behind ArchiveKit - typed queryable columns and a jsonb payload from a single write, why the archive's EntityId is an index but deliberately not a foreign key, and the reflective model configuration that builds every archive table from one method call. Part 4 of the Archive-on-Delete with ArchiveKit series.
You built schema-aware migrations, provisioned tenant A, and everything worked. Tenant B provisions without a single error — and gets no tables. EF Core's model cache is the silent culprit, and IModelCacheKeyFactory is the three-field fix.
Why ArchiveKit's inline archive limit defaults to exactly 14, how EF Core's MaxBatchSize turns archiving into arithmetic, and an honest inventory of every deletion path the interceptor cannot see - synchronous saves, ExecuteDelete, and raw SQL. Part 3 of the Archive-on-Delete with ArchiveKit series.
EF Core wants one database, one model and one migrations history table. Schema-per-tenant breaks all three assumptions. Constructor-injected migrations, a per-schema history table and a replaced IMigrationsAssembly put one migration set in charge of every tenant schema.
The anatomy of ArchiveKit's SaveChangesInterceptor - detecting soft-deleted entities in the change tracker, building archive rows with zero extra database reads, and the one line of state-flip ordering that keeps EF from cascade-deleting the archive you just wrote. Part 2 of the Archive-on-Delete with ArchiveKit series.
Header, route, subdomain or query string: how the platform decides who is asking before it touches any data, how tenant identity becomes a connection string and a schema, and where the caching knives are hidden.
Hard deletes destroy the audit trail; soft deletes clutter live tables forever. Introducing ArchiveKit, a .NET library that intercepts deletions and stores immutable archive snapshots with TTL policies and cascade archiving.
Rename a property, change a type, ship the release - and every payload you stored last year stops deserialising. Introducing VersionKit, a .NET library that declares schema history as attributes and migrates old data on read.
Database-per-tenant, schema-per-tenant, or packed into a shared database? Kicking off a series on building a multi-tenant platform where one EF Core codebase supports all three isolation strategies behind a single control plane.
SaveChanges is already a transaction, until it isn't enough. A tour of explicit transactions, TransactionScope, execution strategies and the failure modes that only show up in production.
Four magic strings in an audit column decide which rows the batch jobs may overwrite and which belong to humans - provenance, workflow state and inter-job protocol smuggled into a field meant for names.
