From 6b2e287def7a26c983949f1b7a16a9107928f7fc Mon Sep 17 00:00:00 2001
From: "Michael J. Sullivan" <sully@msully.net>
Date: Tue, 16 Jan 2024 16:51:48 -0800
Subject: [PATCH] Fix spurious delete/create of constraints with arguments in
 migrations

The bug here was that `@index` was not populated in the `params` link
for concrete constraints by the reflection writer, and so when we
reloaded the schema from the database, it came back in an arbitrary
order.
This bug has been present for a *long* time, as far as I can tell, but
we tended to get "lucky" with the order pg returned the params.

This is a strictly *forward* fix. It can be cherry-picked but it will
only fix things for constraints created once the fix is applied. I'm
working on a backward fix as well.

Fixes #6699.
---
 edb/schema/reflection/writer.py |  7 ++++---
 tests/test_edgeql_ddl.py        | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/edb/schema/reflection/writer.py b/edb/schema/reflection/writer.py
index 30c3e83f5f0..fb80509ddde 100644
--- a/edb/schema/reflection/writer.py
+++ b/edb/schema/reflection/writer.py
@@ -299,12 +299,13 @@ def _build_object_mutation_shape(
             # an ObjectKeyDict collection that allow associating objects
             # with arbitrary values (a transposed ObjectDict).
             target_expr = f"""assert_distinct((
-                FOR v IN {{ json_array_unpack(<json>${var_n}) }}
+                FOR v IN {{ enumerate(json_array_unpack(<json>${var_n})) }}
                 UNION (
                     SELECT {target.get_name(schema)} {{
-                        @value := <str>v[1]
+                        @index := v.0,
+                        @value := <str>v.1[1],
                     }}
-                    FILTER .id = <uuid>v[0]
+                    FILTER .id = <uuid>v.1[0]
                 )
             ))"""
             args = props.get('args', [])
diff --git a/tests/test_edgeql_ddl.py b/tests/test_edgeql_ddl.py
index 0e2577e95ae..cfd740616b5 100644
--- a/tests/test_edgeql_ddl.py
+++ b/tests/test_edgeql_ddl.py
@@ -10190,6 +10190,26 @@ async def test_edgeql_ddl_constraint_09(self):
             CREATE TYPE Comment EXTENDING Text;
         """)
 
+        await self.assert_query_result(
+            """
+            select schema::Constraint {
+                name, params: {name, @index} order by @index
+            }
+            filter .name = 'std::max_len_value'
+            and .subject.name = 'body'
+            and .subject[is schema::Pointer].source.name ='default::Text';
+            """,
+            [
+                {
+                    "name": "std::max_len_value",
+                    "params": [
+                        {"name": "__subject__", "@index": 0},
+                        {"name": "max", "@index": 1}
+                    ]
+                }
+            ],
+        )
+
         await self.con.execute("""
             ALTER TYPE Text
                 ALTER PROPERTY body