Docs Update for C++ [2/4] (#4129)

# Description of Changes

In order to give reviewers a chance to finish in one session the docs
are getting split up for the C++ update. This pass contains the
following section update:
- Tables

# API and ABI breaking changes

N/A

# Expected complexity level and risk

1 - Just documentation additions

# Testing

- [x] Manually tested each block

Author: JasonAtClockwork

docs/docs/00200-core-concepts/00300-tables.md

@@ -164,6 +164,24 @@ pub struct Person {
 The `pub` modifier on the struct follows normal Rust visibility rules and has no meaning to SpacetimeDB. It controls whether the struct is accessible from other Rust modules in your crate, not whether the table is public to clients. Use the `public` attribute in `#[spacetimedb::table]` to control client visibility.
 :::
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+Register the struct with `SPACETIMEDB_STRUCT`, the table with `SPACETIMEDB_TABLE`, then add field constraints:
+
+```cpp
+struct Person {
+    uint32_t id;
+    std::string name;
+    std::string email;
+};
+SPACETIMEDB_STRUCT(Person, id, name, email)
+SPACETIMEDB_TABLE(Person, person, Public)
+FIELD_PrimaryKeyAutoInc(person, id)
+FIELD_Index(person, name)
+FIELD_Unique(person, email)
+```
+
 </TabItem>
 </Tabs>
 
@@ -239,6 +257,29 @@ ctx.db.player().insert(Player { /* ... */ });
 | `name = player` | `ctx.db.player()` |
 | `name = game_session` | `ctx.db.game_session()` |
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+The accessor name matches the table identifier you pass to `SPACETIMEDB_TABLE`:
+
+```cpp
+struct PlayerScores {
+  uint64_t id;
+};
+SPACETIMEDB_STRUCT(PlayerScores, id)
+SPACETIMEDB_TABLE(PlayerScores, player_scores, Public)
+FIELD_PrimaryKeyAutoInc(player_scores, id)
+
+// Accessor matches the table identifier
+ctx.db[player_scores].insert(PlayerScores{ /* ... */ });
+```
+
+| Table Identifier | Accessor |
+|------------------|----------|
+| `user` | `ctx.db[user]` |
+| `player_scores` | `ctx.db[player_scores]` |
+| `game_session` | `ctx.db[game_session]` |
+
 </TabItem>
 </Tabs>
 
@@ -251,6 +292,7 @@ Use idiomatic naming conventions for each language:
 | **TypeScript** | snake_case | `'player_score'` | `ctx.db.playerScore` |
 | **C#** | PascalCase | `Name = "PlayerScore"` | `ctx.Db.PlayerScore` |
 | **Rust** | lower_snake_case | `name = player_score` | `ctx.db.player_score()` |
+| **C++** | lower_snake_case | `player_score` | `ctx.db[player_score]` |
 
 These conventions align with each language's standard style guides and make your code feel natural within its ecosystem.
 
@@ -291,6 +333,25 @@ pub struct User { /* ... */ }
 pub struct Secret { /* ... */ }
 ```
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+```cpp
+struct User {
+  uint64_t id;
+};
+SPACETIMEDB_STRUCT(User, id)
+SPACETIMEDB_TABLE(User, user, Public)
+FIELD_PrimaryKeyAutoInc(user, id)
+
+struct Secret {
+  uint64_t id;
+};
+SPACETIMEDB_STRUCT(Secret, id)
+SPACETIMEDB_TABLE(Secret, secret, Private)
+FIELD_PrimaryKeyAutoInc(secret, id)
+```
+
 </TabItem>
 </Tabs>
 
@@ -388,6 +449,33 @@ if let Some(player) = ctx.db.logged_out_player().identity().find(&ctx.sender())
 }
 ```
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+Apply multiple `SPACETIMEDB_TABLE` macros to the same struct:
+
+```cpp
+struct Player {
+  Identity identity;
+  int32_t player_id;
+  std::string name;
+};
+SPACETIMEDB_STRUCT(Player, identity, player_id, name)
+SPACETIMEDB_TABLE(Player, player, Public)
+SPACETIMEDB_TABLE(Player, logged_out_player, Private)
+FIELD_PrimaryKey(player, identity)
+FIELD_PrimaryKey(logged_out_player, identity)
+FIELD_UniqueAutoInc(player, player_id)
+FIELD_UniqueAutoInc(logged_out_player, player_id)
+
+// Move a row between tables
+auto maybe_logged_out = ctx.db[logged_out_player_identity].find(ctx.sender);
+if (maybe_logged_out) {
+  ctx.db[player].insert(*maybe_logged_out);
+  ctx.db[logged_out_player_identity].delete_by_key(ctx.sender);
+}
+```
+
 </TabItem>
 </Tabs>
 

docs/docs/00200-core-concepts/00300-tables/00200-column-types.md

@@ -132,6 +132,29 @@ These optimizations apply across all supported languages.
 | Special | `TimeDuration` | Relative duration in microseconds |
 | Special | `ScheduleAt` | When a scheduled reducer should execute |
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+| Category | Type | Description |
+|----------|------|-------------|
+| Primitive | `bool` | Boolean value |
+| Primitive | `std::string` | UTF-8 string |
+| Primitive | `float` | 32-bit floating point |
+| Primitive | `double` | 64-bit floating point |
+| Primitive | `int8_t`, `int16_t`, `int32_t`, `int64_t` | Signed integers (8-bit to 64-bit) |
+| Primitive | `uint8_t`, `uint16_t`, `uint32_t`, `uint64_t` | Unsigned integers (8-bit to 64-bit) |
+| Primitive | `SpacetimeDB::i128`, `SpacetimeDB::i256` | Signed 128-bit and 256-bit integers |
+| Primitive | `SpacetimeDB::u128`, `SpacetimeDB::u256` | Unsigned 128-bit and 256-bit integers |
+| Composite | `struct` with `SPACETIMEDB_STRUCT` | Product type for nested data |
+| Composite | `SPACETIMEDB_ENUM` | Sum type (tagged union) |
+| Composite | `std::vector<T>` | Vector of elements |
+| Composite | `std::optional<T>` | Optional value |
+| Special | `Identity` | Unique identity for authentication |
+| Special | `ConnectionId` | Client connection identifier |
+| Special | `Timestamp` | Absolute point in time (microseconds since Unix epoch) |
+| Special | `TimeDuration` | Relative duration in microseconds |
+| Special | `ScheduleAt` | When a scheduled reducer should execute |
+
 </TabItem>
 </Tabs>
 
@@ -289,5 +312,57 @@ pub struct Player {
 }
 ```
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+```cpp
+// Define a nested struct type for coordinates
+struct Coordinates {
+    double x;
+    double y;
+    double z;
+};
+SPACETIMEDB_STRUCT(Coordinates, x, y, z)
+
+// Define unit types for enum variants
+SPACETIMEDB_UNIT_TYPE(Active)
+SPACETIMEDB_UNIT_TYPE(Inactive)
+
+// Define an enum for status
+SPACETIMEDB_ENUM(PlayerStatus,
+    (Active, Active),
+    (Inactive, Inactive),
+    (Suspended, std::string)
+)
+
+struct Player {
+    // Primitive types
+    uint64_t id;
+    std::string name;
+    uint8_t level;
+    uint32_t experience;
+    float health;
+    int64_t score;
+    bool is_online;
+
+    // Composite types
+    Coordinates position;
+    PlayerStatus status;
+    std::vector<uint32_t> inventory;
+    std::optional<uint64_t> guild_id;
+
+    // Special types
+    Identity owner;
+    std::optional<ConnectionId> connection;
+    Timestamp created_at;
+    TimeDuration play_time;
+};
+SPACETIMEDB_STRUCT(Player, id, name, level, experience, health, score, is_online,
+                   position, status, inventory, guild_id,
+                   owner, connection, created_at, play_time)
+SPACETIMEDB_TABLE(Player, player, Public)
+FIELD_PrimaryKeyAutoInc(player, id)
+```
+
 </TabItem>
 </Tabs>

docs/docs/00200-core-concepts/00300-tables/00210-file-storage.md

@@ -11,7 +11,7 @@ SpacetimeDB can store binary data directly in table columns, making it suitable
 
 ## Storing Binary Data Inline
 
-Store binary data using `Vec<u8>` (Rust), `List<byte>` (C#), or `t.array(t.u8())` (TypeScript). This approach keeps data within the database, ensuring it participates in transactions and real-time updates.
+Store binary data using `Vec<u8>` (Rust), `List<byte>` (C#), `std::vector<uint8_t>` (C++), or `t.array(t.u8())` (TypeScript). This approach keeps data within the database, ensuring it participates in transactions and real-time updates.
 
 <Tabs groupId="server-language" queryString>
 <TabItem value="typescript" label="TypeScript">
@@ -120,6 +120,37 @@ pub fn upload_avatar(
 }
 ```
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+```cpp
+struct UserAvatar {
+  uint64_t user_id;
+  std::string mime_type;
+  std::vector<uint8_t> data;  // Binary data stored inline
+  Timestamp uploaded_at;
+};
+SPACETIMEDB_STRUCT(UserAvatar, user_id, mime_type, data, uploaded_at)
+SPACETIMEDB_TABLE(UserAvatar, user_avatar, Public)
+FIELD_PrimaryKey(user_avatar, user_id)
+
+SPACETIMEDB_REDUCER(upload_avatar, ReducerContext ctx, 
+  uint64_t user_id, std::string mime_type, std::vector<uint8_t> data) {
+  // Delete existing avatar if present
+  ctx.db[user_avatar_user_id].delete_by_key(user_id);
+
+  // Insert new avatar
+  ctx.db[user_avatar].insert(UserAvatar{
+    .user_id = user_id,
+    .mime_type = mime_type,
+    .data = data,
+    .uploaded_at = ctx.timestamp,
+  });
+    
+  return Ok();
+}
+```
+
 </TabItem>
 </Tabs>
 
@@ -273,6 +304,41 @@ pub fn register_document(
 }
 ```
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+```cpp
+struct Document {
+    uint64_t id;
+    Identity owner_id;
+    std::string filename;
+    std::string mime_type;
+    uint64_t size_bytes;
+    std::string storage_url;  // Reference to external storage
+    Timestamp uploaded_at;
+};
+SPACETIMEDB_STRUCT(Document, id, owner_id, filename, mime_type, size_bytes, storage_url, uploaded_at)
+SPACETIMEDB_TABLE(Document, document, Public)
+FIELD_PrimaryKeyAutoInc(document, id)
+FIELD_Index(document, owner_id)
+
+// Called after uploading file to external storage
+SPACETIMEDB_REDUCER(register_document, ReducerContext ctx,
+    std::string filename, std::string mime_type, uint64_t size_bytes, std::string storage_url) {
+    ctx.db[document].insert(Document{
+        .id = 0,  // auto-increment
+        .owner_id = ctx.sender,
+        .filename = filename,
+        .mime_type = mime_type,
+        .size_bytes = size_bytes,
+        .storage_url = storage_url,
+        .uploaded_at = ctx.timestamp,
+    });
+    
+    return Ok();
+}
+```
+
 </TabItem>
 </Tabs>
 
@@ -735,6 +801,25 @@ pub struct Image {
 }
 ```
 
+</TabItem>
+<TabItem value="cpp" label="C++">
+
+```cpp
+struct Image {
+    uint64_t id;
+    Identity owner_id;
+    std::vector<uint8_t> thumbnail;  // Small preview stored inline
+    std::string original_url;        // Large original in external storage
+    uint32_t width;
+    uint32_t height;
+    Timestamp uploaded_at;
+};
+SPACETIMEDB_STRUCT(Image, id, owner_id, thumbnail, original_url, width, height, uploaded_at)
+SPACETIMEDB_TABLE(Image, image, Public)
+FIELD_PrimaryKeyAutoInc(image, id)
+FIELD_Index(image, owner_id)
+```
+
 </TabItem>
 </Tabs>
 

docs/docs/00200-core-concepts/00300-tables/00230-auto-increment.md

@@ -35,6 +35,8 @@ spacetimedb.reducer('add_post', { title: t.string() }, (ctx, { title }) => {
 
 Use the `.autoInc()` method on a column builder.
 
+Auto-increment columns must be integer types: `t.i8()`, `t.u8()`, `t.i16()`, `t.u16()`, `t.i32()`, `t.u32()`, `t.i64()`, `t.u64()`, `t.i128()`, `t.u128()`, `t.i256()`, or `t.u256()`.
+
 </TabItem>
 <TabItem value="csharp" label="C#">
 
@@ -60,6 +62,8 @@ public static void AddPost(ReducerContext ctx, string title)
 
 Use the `[SpacetimeDB.AutoInc]` attribute.
 
+Auto-increment columns must be integer types: `sbyte`, `byte`, `short`, `ushort`, `int`, `uint`, `long`, `ulong`, `SpacetimeDB.I128`, `SpacetimeDB.U128`, `SpacetimeDB.I256`, or `SpacetimeDB.U256`.
+
 </TabItem>
 <TabItem value="rust" label="Rust">
 
@@ -86,10 +90,35 @@ fn add_post(ctx: &ReducerContext, title: String) -> Result<(), String> {
 
 Use the `#[auto_inc]` attribute.
 
+Auto-increment columns must be integer types: `i8`, `i16`, `i32`, `i64`, `i128`, `u8`, `u16`, `u32`, `u64`, or `u128`.
+
 </TabItem>
-</Tabs>
+<TabItem value="cpp" label="C++">
+
+```cpp
+struct Post {
+    uint64_t id;
+    std::string title;
+};
+SPACETIMEDB_STRUCT(Post, id, title)
+SPACETIMEDB_TABLE(Post, post, Public)
+FIELD_PrimaryKeyAutoInc(post, id)
+
+SPACETIMEDB_REDUCER(add_post, ReducerContext ctx, std::string title) {
+    // Pass 0 for the auto-increment field
+    auto inserted = ctx.db[post].insert(Post{0, title});
+    // inserted.id now contains the assigned value
+    LOG_INFO("Created post with id: " + std::to_string(inserted.id));
+    return Ok();
+}
+```
+
+Use the `FIELD_PrimaryKeyAutoInc(table, field)` macro after table registration.
 
-Auto-increment columns must be integer types (`u8`, `u16`, `u32`, `u64`, `i8`, `i16`, `i32`, `i64`, etc.).
+Auto-increment columns must be integer types: `int8_t`, `int16_t`, `int32_t`, `int64_t`, `uint8_t`, `uint16_t`, `uint32_t`, `uint64_t`, `SpacetimeDB::i128`, `SpacetimeDB::u128`, `SpacetimeDB::i256`, or `SpacetimeDB::u256`.
+
+</TabItem>
+</Tabs>
 
 ## Trigger Value