Add primary key to schema

We need to know the primary key to perform efficient batch updates.

src/migrations/create_table.rs

@@ -75,6 +75,8 @@ impl Action for CreateTable {
 
     fn update_schema(&self, schema: &mut Schema) -> anyhow::Result<()> {
         let mut table = Table::new(self.name.to_string());
+        table.primary_key = self.primary_key.clone();
+
         for column in &self.columns {
             table.add_column(crate::schema::Column {
                 name: column.name.to_string(),

src/schema.rs

@@ -42,6 +42,7 @@ impl Default for Schema {
 pub struct Table {
     pub name: String,
     pub columns: Vec<Column>,
+    pub primary_key: Vec<String>,
     #[serde(skip)]
     pub has_is_new: bool,
 }
@@ -50,6 +51,7 @@ impl Table {
     pub fn new(name: impl Into<String>) -> Table {
         Table {
             name: name.into(),
+            primary_key: vec![],
             columns: vec![],
             has_is_new: false,
         }