Add EnsureCreated support for DynamoDB tables and indexes

[j-d-ha]

Summary

Add DynamoDB EnsureCreated / schema creation support following EF Core Cosmos and relational provider patterns.

Current provider can translate/write items, but DynamoDB Local/test containers require physical tables to exist before seed/save writes can run. This blocks specification tests and any TestStore.InitializeAsync flow that assumes provider EnsureCreated can provision backing store resources.

Desired provider behavior

Follow Cosmos/relational pattern:

• SaveChanges must not auto-create tables.
• Calling DbContext.Database.EnsureCreated() / EnsureCreatedAsync() is explicit opt-in to create missing backing resources.
• If caller does not call EnsureCreated, tables are expected to be provisioned externally.
• MVP can be model-driven with provider defaults; no per-call options required initially.

Relational precedent:

• EnsureCreated() creates database/tables from model.
• Opt-out is: do not call EnsureCreated; use migrations/external schema management.

Cosmos precedent:

• EnsureCreatedAsync() creates database and containers via CreateDatabaseIfNotExistsAsync / CreateContainerIfNotExistsAsync.
• Container definitions are derived from EF model annotations: container name, partition key, TTL, throughput, indexes, etc.
• No per-call options struct; behavior is model-driven.

Mongo precedent for later consideration:

• Mongo adds provider-specific MongoDatabaseCreationOptions to control missing collections/indexes.
• We can defer analogous Dynamo options until needed.

Scope

Implement DynamoDB database/table creation support sufficient for local/test-container and normal EnsureCreated usage.

Required

• Register DynamoDB database creator service:
  • IDatabaseCreator implementation, e.g. DynamoDatabaseCreator.
  • Support sync and async EF APIs where practical:
    • EnsureCreated() / EnsureCreatedAsync()
    • EnsureDeleted() / EnsureDeletedAsync()
    • CanConnect() / CanConnectAsync() if feasible.
• Derive physical table definitions from existing provider metadata.
• Create missing DynamoDB tables before model seed/save writes run.
• Wait for table active after creation.
• Delete mapped tables for EnsureDeleted.
• Integrate with EF model seed/UseSeeding paths if applicable, matching Cosmos behavior.

Table creation

For each table group:

• Table name from centralized table-group metadata:
  • src/EntityFrameworkCore.DynamoDb/Extensions/DynamoModelExtensions.cs
  • GetTableGroupName() / ComputeTableGroupName()
• Key source from inheritance-aware key metadata:
  • ResolveKeyMappedEntityType()
• Base table key:
  • partition key property -> DynamoDB HASH key
  • optional sort key property -> DynamoDB RANGE key
• Attribute names from GetAttributeName().
• Attribute scalar types from effective provider CLR/key type logic:
  • string -> ScalarAttributeType.S
  • numeric -> ScalarAttributeType.N
  • byte[] -> ScalarAttributeType.B

Index creation

Create configured secondary indexes from existing metadata:

• Runtime index model:
  • src/EntityFrameworkCore.DynamoDb/Metadata/Internal/DynamoRuntimeTableModel.cs
  • DynamoRuntimeTableModel
  • DynamoTableDescriptor
  • DynamoIndexDescriptor
• Runtime initializer that already builds index descriptors:
  • src/EntityFrameworkCore.DynamoDb/Infrastructure/Internal/DynamoModelRuntimeInitializer.cs
  • BuildRuntimeTableModel
  • BuildSourceDescriptors
  • BuildGlobalSecondaryIndexDescriptor
  • BuildLocalSecondaryIndexDescriptor
• Index annotations/extensions:
  • src/EntityFrameworkCore.DynamoDb/Extensions/DynamoIndexExtensions.cs
  • DynamoSecondaryIndexKind.Global
  • DynamoSecondaryIndexKind.Local
  • DynamoSecondaryIndexProjectionType

Need map descriptors to AWS SDK table create inputs:

• GlobalSecondaryIndexes
• LocalSecondaryIndexes
• KeySchema
• AttributeDefinitions
• projection type

Deduplicate AttributeDefinitions across table and indexes.

Billing/defaults

MVP default:

• Use BillingMode.PAY_PER_REQUEST so no throughput config is required and DynamoDB Local/test containers work out of box.

Later enhancement:

• Add provider model annotations/options for billing mode and provisioned throughput if needed.
• Possible provider-specific API similar to Mongo:
  • DynamoDatabaseCreationOptions(CreateMissingTables, CreateSecondaryIndexes, BillingMode, ...)

Important current code references

Provider registration likely belongs near:

• src/EntityFrameworkCore.DynamoDb/Extensions/DynamoServiceCollectionExtensions.cs (or equivalent service registration file)

Write paths currently assume tables exist:

• src/EntityFrameworkCore.DynamoDb/Storage/DynamoSaveChangesPlanner.cs
• src/EntityFrameworkCore.DynamoDb/Storage/DynamoPartiqlStatementFactory.cs
• src/EntityFrameworkCore.DynamoDb/Storage/DynamoWriteExecutor.cs
• src/EntityFrameworkCore.DynamoDb/Storage/DynamoClientWrapper.cs

Runtime table/index metadata already exists and should be reused:

• src/EntityFrameworkCore.DynamoDb/Metadata/Internal/DynamoRuntimeTableModel.cs
• src/EntityFrameworkCore.DynamoDb/Infrastructure/Internal/DynamoModelRuntimeInitializer.cs

Table/key helpers recently centralized:

• src/EntityFrameworkCore.DynamoDb/Extensions/DynamoModelExtensions.cs
  • GetTableGroupName()
  • ComputeTableGroupName()
  • ResolveTableMappedEntityType()
  • ResolveKeyMappedEntityType()

Test infra currently only ensures client exists, not tables:

• tests/EntityFrameworkCore.DynamoDb.SpecificationTests/TestUtilities/DynamoTestStore.cs

Acceptance criteria

• context.Database.EnsureCreated() creates all required DynamoDB tables for mapped root/table groups.
• context.Database.EnsureCreatedAsync() async equivalent works.
• DynamoDB Local/test container seed writes no longer fail due to missing table.
• Tables use correct PK/SK attribute names and DynamoDB scalar types.
• Configured GSIs and LSIs are created.
• Shared-table/entity inheritance mappings create one physical table per table group.
• Calling EnsureCreated repeatedly is idempotent.
• EnsureDeleted removes mapped tables and ignores missing tables.
• Unit/integration tests cover:
  • PK-only table
  • PK+SK table
  • TPH/shared table inheritance
  • GSI
  • LSI
  • repeated EnsureCreated
  • seed data after creation

Notes

This work should land before continuing current spec-test branch work, because tests using DynamoDB Local need actual table definitions. Provider should not add table creation to SaveChanges; explicit EnsureCreated is EF-compatible opt-in.