Fix unique column in schema sync (#2971)

* Fix unique column in schema sync

* Move code

* Fixup

Author: tyt2y3

sea-orm-arrow/Cargo.toml

@@ -25,6 +25,3 @@ with-bigdecimal   = ["sea-query/with-bigdecimal"]
 with-chrono       = ["sea-query/with-chrono"]
 with-rust_decimal = ["sea-query/with-rust_decimal"]
 with-time         = ["sea-query/with-time"]
-
-[patch.crates-io]
-# sea-query = { path = "../../sea-query" }

src/schema/builder.rs

@@ -1,8 +1,8 @@
 use super::{Schema, TopologicalSort};
 use crate::{ConnectionTrait, DbBackend, DbErr, EntityTrait, Statement};
 use sea_query::{
-    ForeignKeyCreateStatement, IndexCreateStatement, TableAlterStatement, TableCreateStatement,
-    TableName, TableRef, extension::postgres::TypeCreateStatement,
+    ForeignKeyCreateStatement, Index, IndexCreateStatement, IntoIden, TableAlterStatement,
+    TableCreateStatement, TableName, TableRef, extension::postgres::TypeCreateStatement,
 };
 
 /// A schema builder that can take a registry of Entities and synchronize it with database.
@@ -387,6 +387,46 @@ impl EntitySchemaInfo {
                 db.execute(&stmt).await?;
             }
         }
+        if let Some(existing_table) = existing_table {
+            // For columns with a column-level UNIQUE constraint (#[sea_orm(unique)]) that
+            // already exist in the table but do not yet have a unique index, create one.
+            for column_def in self.table.get_columns() {
+                if column_def.get_column_spec().unique {
+                    let col_name = column_def.get_column_name();
+                    let col_exists = existing_table
+                        .get_columns()
+                        .iter()
+                        .any(|c| c.get_column_name() == col_name);
+                    if !col_exists {
+                        // Column is being added in this sync pass; the ALTER TABLE ADD COLUMN
+                        // will include the UNIQUE inline, so no separate index needed.
+                        continue;
+                    }
+                    let already_unique = existing_table.get_indexes().iter().any(|idx| {
+                        if !idx.is_unique_key() {
+                            return false;
+                        }
+                        let cols = idx.get_index_spec().get_column_names();
+                        cols.len() == 1 && cols[0] == col_name
+                    });
+                    if !already_unique {
+                        let table_name =
+                            self.table.get_table_name().expect("table must have a name");
+                        let tbl_str = table_name.sea_orm_table().to_string();
+                        let table_ref = table_name.clone();
+                        db.execute(
+                            Index::create()
+                                .name(format!("idx-{tbl_str}-{col_name}"))
+                                .table(table_ref)
+                                .col(col_name.into_iden())
+                                .unique()
+                                .if_not_exists(),
+                        )
+                        .await?;
+                    }
+                }
+            }
+        }
         if let Some(existing_table) = existing_table {
             // find all unique keys from existing table
             // if it no longer exist in new schema, drop it
@@ -401,6 +441,23 @@ impl EntitySchemaInfo {
                             break;
                         }
                     }
+                    // Also check if the unique index corresponds to a column-level UNIQUE
+                    // constraint (from #[sea_orm(unique)]). These are embedded in the CREATE
+                    // TABLE column definition and not tracked in self.indexes, so we must not
+                    // try to drop them during sync.
+                    if !has_index {
+                        let index_cols = existing_index.get_index_spec().get_column_names();
+                        if index_cols.len() == 1 {
+                            for column_def in self.table.get_columns() {
+                                if column_def.get_column_name() == index_cols[0]
+                                    && column_def.get_column_spec().unique
+                                {
+                                    has_index = true;
+                                    break;
+                                }
+                            }
+                        }
+                    }
                     if !has_index {
                         if let Some(drop_existing) = existing_index.get_index_spec().get_name() {
                             db.execute(sea_query::Index::drop().name(drop_existing))

tests/schema_sync_tests.rs

@@ -0,0 +1,226 @@
+#![allow(unused_imports, dead_code)]
+
+pub mod common;
+
+use crate::common::TestContext;
+use sea_orm::{
+    DatabaseConnection, DbErr,
+    entity::*,
+    query::*,
+    sea_query::{Condition, Expr, Query},
+};
+
+// Scenario 1: table is first synced with a `#[sea_orm(unique)]` column already
+// present. Repeated syncs must not drop the column-level unique constraint.
+mod item_v1 {
+    use sea_orm::entity::prelude::*;
+
+    #[sea_orm::model]
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "sync_item")]
+    pub struct Model {
+        #[sea_orm(primary_key)]
+        pub id: i32,
+        #[sea_orm(unique)]
+        pub name: String,
+    }
+
+    impl ActiveModelBehavior for ActiveModel {}
+}
+
+// Scenario 2a: initial version of the table — no unique column yet.
+mod product_v1 {
+    use sea_orm::entity::prelude::*;
+
+    #[sea_orm::model]
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "sync_product")]
+    pub struct Model {
+        #[sea_orm(primary_key)]
+        pub id: i32,
+    }
+
+    impl ActiveModelBehavior for ActiveModel {}
+}
+
+// Scenario 2b: updated version — a unique column is added.
+mod product_v2 {
+    use sea_orm::entity::prelude::*;
+
+    #[sea_orm::model]
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "sync_product")]
+    pub struct Model {
+        #[sea_orm(primary_key)]
+        pub id: i32,
+        #[sea_orm(unique)]
+        pub sku: String,
+    }
+
+    impl ActiveModelBehavior for ActiveModel {}
+}
+
+// Scenario 3a: initial version — column exists without UNIQUE.
+mod user_v1 {
+    use sea_orm::entity::prelude::*;
+
+    #[sea_orm::model]
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "sync_user")]
+    pub struct Model {
+        #[sea_orm(primary_key)]
+        pub id: i32,
+        pub email: String,
+    }
+
+    impl ActiveModelBehavior for ActiveModel {}
+}
+
+// Scenario 3b: updated version — the existing column is made unique.
+mod user_v2 {
+    use sea_orm::entity::prelude::*;
+
+    #[sea_orm::model]
+    #[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
+    #[sea_orm(table_name = "sync_user")]
+    pub struct Model {
+        #[sea_orm(primary_key)]
+        pub id: i32,
+        #[sea_orm(unique)]
+        pub email: String,
+    }
+
+    impl ActiveModelBehavior for ActiveModel {}
+}
+
+/// Regression test for <https://github.com/SeaQL/sea-orm/issues/2970>.
+///
+/// A table with a `#[sea_orm(unique)]` column is created on the first sync.
+/// The subsequent sync must not attempt to drop the column-level unique index.
+#[sea_orm_macros::test]
+async fn test_sync_unique_column_no_drop() -> Result<(), DbErr> {
+    let ctx = TestContext::new("test_sync_unique_column_no_drop").await;
+    let db = &ctx.db;
+
+    #[cfg(feature = "schema-sync")]
+    {
+        // First sync: creates the table with the unique column
+        db.get_schema_builder()
+            .register(item_v1::Entity)
+            .sync(db)
+            .await?;
+
+        // Second sync: must not try to drop the column-level unique index
+        db.get_schema_builder()
+            .register(item_v1::Entity)
+            .sync(db)
+            .await?;
+
+        #[cfg(feature = "sqlx-postgres")]
+        assert!(
+            pg_index_exists(db, "sync_item", "sync_item_name_key").await?,
+            "unique index on `sync_item.name` should still exist after repeated sync"
+        );
+    }
+
+    Ok(())
+}
+
+/// Regression test for <https://github.com/SeaQL/sea-orm/issues/2970>.
+///
+/// A unique column is added to an existing table via sync (ALTER TABLE ADD
+/// COLUMN … UNIQUE), which creates a column-level unique index. A subsequent
+/// sync must not attempt to drop that index.
+#[sea_orm_macros::test]
+#[cfg(not(any(feature = "sqlx-sqlite", feature = "rusqlite")))]
+async fn test_sync_add_unique_column_no_drop() -> Result<(), DbErr> {
+    let ctx = TestContext::new("test_sync_add_unique_column_no_drop").await;
+    let db = &ctx.db;
+
+    #[cfg(feature = "schema-sync")]
+    {
+        // First sync: creates the table without the unique column
+        db.get_schema_builder()
+            .register(product_v1::Entity)
+            .sync(db)
+            .await?;
+
+        // Second sync: adds the unique column via ALTER TABLE ADD COLUMN … UNIQUE
+        db.get_schema_builder()
+            .register(product_v2::Entity)
+            .sync(db)
+            .await?;
+
+        // Third sync: must not try to drop the unique index created above
+        db.get_schema_builder()
+            .register(product_v2::Entity)
+            .sync(db)
+            .await?;
+
+        #[cfg(feature = "sqlx-postgres")]
+        assert!(
+            pg_index_exists(db, "sync_product", "sync_product_sku_key").await?,
+            "unique index on `sync_product.sku` should still exist after repeated sync"
+        );
+    }
+
+    Ok(())
+}
+
+/// Scenario 3: an existing column is made unique in a later sync.
+///
+/// When a column that already exists in the DB is annotated with
+/// `#[sea_orm(unique)]`, the sync must create a unique index for it.
+#[sea_orm_macros::test]
+async fn test_sync_make_existing_column_unique() -> Result<(), DbErr> {
+    let ctx = TestContext::new("test_sync_make_existing_column_unique").await;
+    let db = &ctx.db;
+
+    #[cfg(feature = "schema-sync")]
+    {
+        // First sync: creates the table with a plain (non-unique) email column
+        db.get_schema_builder()
+            .register(user_v1::Entity)
+            .sync(db)
+            .await?;
+
+        // Second sync: email is now marked unique — should create the unique index
+        db.get_schema_builder()
+            .register(user_v2::Entity)
+            .sync(db)
+            .await?;
+
+        // Third sync: must not try to drop or re-create the index
+        db.get_schema_builder()
+            .register(user_v2::Entity)
+            .sync(db)
+            .await?;
+
+        #[cfg(feature = "sqlx-postgres")]
+        assert!(
+            pg_index_exists(db, "sync_user", "idx-sync_user-email").await?,
+            "unique index on `sync_user.email` should be created when column is made unique"
+        );
+    }
+
+    Ok(())
+}
+
+#[cfg(feature = "sqlx-postgres")]
+async fn pg_index_exists(db: &DatabaseConnection, table: &str, index: &str) -> Result<bool, DbErr> {
+    db.query_one(
+        Query::select()
+            .expr(Expr::cust("COUNT(*) > 0"))
+            .from("pg_indexes")
+            .cond_where(
+                Condition::all()
+                    .add(Expr::cust("schemaname = CURRENT_SCHEMA()"))
+                    .add(Expr::col("tablename").eq(table))
+                    .add(Expr::col("indexname").eq(index)),
+            ),
+    )
+    .await?
+    .unwrap()
+    .try_get_by_index(0)
+    .map_err(DbErr::from)
+}