docs(filter-sync and dozer): explain that there are two sync types 🚗 (#…

…3179)

docs/components/common-text/FilterTypes.mdx

@@ -0,0 +1,13 @@
+import { Callout } from "nextra/components";
+
+<Callout type="info">
+MUD initial data hydration, and therefore filtering, comes in two flavors: [Dozer](/state-query/dozer) and [generic](/guides/hello-world/filter-sync).
+Note that this is for the initial hydration, currently limits on on-going synchronization are limited to [the generic method](/guides/hello-world/filter-sync).
+
+|                      | Dozer                                                                                                                                              | Generic                                                                                                                                                   |
+| -------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| Filtering            | Can filter on most SQL functions                                                                                                                   | Can only filter on tables and the first two key fields (limited by [`eth_getLogs`](https://ethereum.github.io/execution-apis/api-documentation/) filters) |
+| Availability         | [Redstone](https://redstone.xyz/docs/network-info), [Garnet](https://garnetchain.com/docs/network-info), or elsewhere if you run your own instance | Any EVM chain                                                                                                                                             |
+| Security assumptions | The Dozer instance returns accurate information                                                                                                    | The endpoint returns accurate information (same assumption as any other blockchain app)                                                                   |
+
+</Callout>

docs/pages/guides/hello-world/filter-sync.mdx

@@ -1,10 +1,25 @@
 import { CollapseCode } from "../../../components/CollapseCode";
+import FilterTypes from "../../../components/common-text/FilterTypes.mdx";
 
 # Filter data synchronization
 
 In this tutorial you modify `networkSetup.ts` to filter the information you synchronize.
 Filtering information this way allows you to reduce the use of network resources and makes loading times faster.
 
+<FilterTypes />
+
+<details>
+
+<summary>Why are only the first two key fields available for filtering?</summary>
+
+Ethereum log entries can have [up to four indexed fields](https://www.evm.codes/?fork=cancun#a4).
+However, Solidity only supports [three indexed fields](https://www.alchemy.com/overviews/solidity-events) because the first indexed field is used for the event name and type.
+In MUD, [this field](https://github.com/latticexyz/mud/blob/main/packages/store/src/IStoreEvents.sol) specifies whether [a new record is created](https://github.com/latticexyz/mud/blob/main/packages/store/src/IStoreEvents.sol#L26-L32), a record is changed (either [static fields](https://github.com/latticexyz/mud/blob/main/packages/store/src/IStoreEvents.sol#L43) or [dynamic fields](https://github.com/latticexyz/mud/blob/main/packages/store/src/IStoreEvents.sol#L56-L64)), or [a record is deleted](https://github.com/latticexyz/mud/blob/main/packages/store/src/IStoreEvents.sol#L71).
+The second indexed fields is always the table's [resource ID](/world/resource-ids).
+This leaves two fields for key fields.
+
+</details>
+
 ## Setup
 
 To see the effects of filtering we need a table with entries to filter. To get such a table:

docs/pages/state-query/dozer.mdx

@@ -1,15 +1,22 @@
 import { CollapseCode } from "../../components/CollapseCode";
+import FilterTypes from "../../components/common-text/FilterTypes.mdx";
 import { Callout } from "nextra/components";
 
 # Dozer
 
-If there is a dozer instance serving a blockchain, as there is for [Redstone](https://redstone.xyz/) and [Garnet](https://garnetchain.com/docs/what-is-redstone), you can use it to run queries on the data of any `World` on that blockchain.
+<FilterTypes />
+
+If there is a dozer instance serving a blockchain, as there is for [Redstone](https://redstone.xyz/) and [Garnet](https://garnetchain.com/docs/what-is-redstone), you can use it to:
+
+- Run queries on the data of any `World` on that blockchain.
+- [Speed up the initial hydration](#dozer-with-mud-synchronization) by reducing the amount of data that needs to be synchronized.
+  This is important for the user experience, because until the initial hydration is done the client is typically unusable.
 
 The query language is a subset of [the SQL `SELECT` command](<https://en.wikipedia.org/wiki/Select_(SQL)>).
 
 ## Dozer URLs
 
-- [Redstone](https://redstone.xyz/) dozer `https://dozer.mud.redstonechain.com/q`
+- [Redstone](https://redstone.xyz/) dozer - `https://dozer.mud.redstonechain.com/q`
 - [Garnet](https://garnetchain.com/) dozer - `https://dozer.mud.garnetchain.com/q`
 
 ## Example `World`
@@ -433,7 +440,7 @@ The actual records.
 
 ## Dozer with MUD synchronization
 
-Of course, you can also add dozer to a MUD client with synchronization.
+You can also add dozer to a MUD client to speed up the initial hydration.
 
 ### Create a client to access the `World`
 
@@ -495,7 +502,7 @@ To update the client, you change `packages/client/src/mud/setupNetwork.ts` to:
 
 <CollapseCode>
 
-```typescript filename="setupNetwork.ts" copy showLineNumbers {17-21, 84-101, 111-112}
+```typescript filename="setupNetwork.ts" copy showLineNumbers {17, 80-97, 106-107}
 /*
  * The MUD client code is built on top of viem
  * (https://viem.sh/docs/getting-started.html).