Created Querying in Chunks for Big Queries (markdown)

Querying-in-Chunks-for-Big-Queries.md

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+## The Query Chunks Feature
+
+It's very unusual for us to need to load a number of records from the
+database that might be too big for fitting in memory, e.g. load all the
+users and send them somewhere. But it might happen.
+
+For these cases, it's best to load chunks of data at a time so
+that we can work on a substantial amount of data at a time and never
+overload our memory capacity. For this use-case we have a specific
+function called `QueryChunks`:
+
+```golang
+err = db.QueryChunks(ctx, ksql.ChunkParser{
+	Query:     "SELECT * FROM users WHERE type = ?",
+	Params:    []interface{}{usersType},
+	ChunkSize: 100,
+	ForEachChunk: func(users []User) error {
+		err := sendUsersSomewhere(users)
+		if err != nil {
+			// This will abort the QueryChunks loop and return this error
+			return err
+		}
+		return nil
+	},
+})
+if err != nil {
+	panic(err.Error())
+}
+```
+
+Its signature is more complicated than the other two Query\* methods,
+thus, it is advisable to always prefer using the other two when possible
+reserving this one for the rare use-cases where you are actually
+loading big sections of the database into memory.
+