fix(migrations): on cockroach db wrap migration execution on the shad…

…ow db into a transaction to speed it up (#5138)

schema-engine/connectors/sql-schema-connector/src/flavour/postgres.rs

@@ -492,7 +492,11 @@ impl SqlFlavour for PostgresFlavour {
                 .params()
                 .and_then(|p| p.connector_params.shadow_database_connection_string.clone())
         });
-        let mut shadow_database = PostgresFlavour::default();
+        let mut shadow_database = if self.is_cockroachdb() {
+            PostgresFlavour::new_cockroach()
+        } else {
+            PostgresFlavour::default()
+        };
 
         match shadow_database_connection_string {
             Some(shadow_database_connection_string) => Box::pin(async move {

schema-engine/connectors/sql-schema-connector/src/flavour/postgres/native/shadow_db.rs

@@ -1,3 +1,4 @@
+use crate::flavour::postgres::PostgresProvider::CockroachDb;
 use crate::flavour::{PostgresFlavour, SqlFlavour};
 use schema_connector::{migrations_directory::MigrationDirectory, ConnectorResult};
 use schema_connector::{ConnectorError, Namespaces};
@@ -8,6 +9,15 @@ pub async fn sql_schema_from_migrations_history(
     mut shadow_db: PostgresFlavour,
     namespaces: Option<Namespaces>,
 ) -> ConnectorResult<SqlSchema> {
+    if shadow_db.provider == CockroachDb {
+        // CockroachDB is very slow in applying DDL statements.
+        // A workaround to it is to run the statements in a transaction block. This comes with some
+        // drawbacks and limitations though, so we only apply this when creating a shadow db.
+        // See https://www.cockroachlabs.com/docs/stable/online-schema-changes#limitations
+        // Original GitHub issue with context: https://github.com/prisma/prisma/issues/12384#issuecomment-1152523689
+        shadow_db.raw_cmd("BEGIN;").await?;
+    }
+
     for migration in migrations {
         let script = migration.read_migration_script()?;
 
@@ -25,5 +35,9 @@ pub async fn sql_schema_from_migrations_history(
             })?;
     }
 
+    if shadow_db.provider == CockroachDb {
+        shadow_db.raw_cmd("COMMIT;").await?;
+    }
+
     shadow_db.describe_schema(namespaces).await
 }