store: Clear the entity count when truncating a deployment

We used to count entities, but we know the result is 0 because all the
tables we are counting are empty

Author: lutter

store/postgres/src/deployment.rs

@@ -1249,17 +1249,12 @@ pub fn update_entity_count(
     Ok(())
 }
 
-/// Set the deployment's entity count to whatever `full_count_query` produces
-pub fn set_entity_count(
-    conn: &mut PgConnection,
-    site: &Site,
-    full_count_query: &str,
-) -> Result<(), StoreError> {
+/// Set the deployment's entity count back to `0`
+pub fn clear_entity_count(conn: &mut PgConnection, site: &Site) -> Result<(), StoreError> {
     use subgraph_deployment as d;
 
-    let full_count_query = format!("({})", full_count_query);
     update(d::table.filter(d::id.eq(site.id)))
-        .set(d::entity_count.eq(sql(&full_count_query)))
+        .set(d::entity_count.eq(BigDecimal::from(0)))
         .execute(conn)?;
     Ok(())
 }

store/postgres/src/deployment_store.rs

@@ -1313,7 +1313,7 @@ impl DeploymentStore {
 
                 let event = if truncate {
                     let event = layout.truncate_tables(conn)?;
-                    deployment::set_entity_count(conn, site.as_ref(), layout.count_query.as_str())?;
+                    deployment::clear_entity_count(conn, site.as_ref())?;
                     event
                 } else {
                     let (event, count) = layout.revert_block(conn, block)?;