diff --git a/store/postgres/src/relational/query_tests.rs b/store/postgres/src/relational/query_tests.rs
index 3b4582c5b5b..dc557d78ebe 100644
--- a/store/postgres/src/relational/query_tests.rs
+++ b/store/postgres/src/relational/query_tests.rs
@@ -13,7 +13,9 @@ use crate::{
     block_range::BoundSide,
     layout_for_tests::{Namespace, make_dummy_site},
     relational::{Catalog, ColumnType, Layout},
-    relational_queries::{FindRangeQuery, FromColumnValue, InsertQuery},
+    relational_queries::{
+        FindPossibleDeletionsQuery, FindRangeQuery, FromColumnValue, InsertQuery,
+    },
 };
 
 use crate::relational_queries::Filter;
@@ -200,6 +202,112 @@ fn test_id_type_casting(table: &crate::relational::Table, expected_cast: &str, t
     );
 }
 
+#[test]
+fn find_possible_deletions_query_id_type_casting() {
+    let string_schema = "
+    type StringEntity @entity {
+        id: String!,
+        name: String
+    }";
+
+    let bytes_schema = "
+    type BytesEntity @entity {
+        id: Bytes!,
+        address: Bytes
+    }";
+
+    let int8_schema = "
+    type Int8Entity @entity {
+        id: Int8!,
+        value: Int8
+    }";
+
+    let string_layout = test_layout(string_schema);
+    let bytes_layout = test_layout(bytes_schema);
+    let int8_layout = test_layout(int8_schema);
+
+    let string_table = string_layout
+        .table_for_entity(
+            &string_layout
+                .input_schema
+                .entity_type("StringEntity")
+                .unwrap(),
+        )
+        .unwrap();
+    let bytes_table = bytes_layout
+        .table_for_entity(
+            &bytes_layout
+                .input_schema
+                .entity_type("BytesEntity")
+                .unwrap(),
+        )
+        .unwrap();
+    let int8_table = int8_layout
+        .table_for_entity(&int8_layout.input_schema.entity_type("Int8Entity").unwrap())
+        .unwrap();
+
+    test_possible_deletions_id_type_casting(
+        string_table.as_ref(),
+        "e.id::bytea",
+        "String ID should be cast to bytea",
+    );
+    test_possible_deletions_id_type_casting(
+        bytes_table.as_ref(),
+        "e.id",
+        "Bytes ID should remain as e.id",
+    );
+    test_possible_deletions_id_type_casting(
+        int8_table.as_ref(),
+        "e.id::text::bytea",
+        "Int8 ID should be cast to text then bytea",
+    );
+
+    let tables = vec![
+        string_table.as_ref(),
+        bytes_table.as_ref(),
+        int8_table.as_ref(),
+    ];
+    let query = FindPossibleDeletionsQuery::new(&tables, 100);
+    let sql = debug_query::<Pg, _>(&query).to_string();
+
+    assert!(
+        sql.contains("id::bytea"),
+        "String entity ID casting should be present in possible-deletions UNION query, got: {}",
+        sql
+    );
+    assert!(
+        sql.contains("e.id"),
+        "Bytes entity ID should be present in possible-deletions UNION query"
+    );
+    assert!(
+        sql.contains("id::text::bytea"),
+        "Int8 entity ID casting should be present in possible-deletions UNION query, got: {}",
+        sql
+    );
+    assert!(
+        sql.contains("union all"),
+        "Multiple tables should generate UNION ALL queries"
+    );
+}
+
+fn test_possible_deletions_id_type_casting(
+    table: &crate::relational::Table,
+    expected_cast: &str,
+    test_name: &str,
+) {
+    let tables = vec![table];
+    let query = FindPossibleDeletionsQuery::new(&tables, 100);
+    let sql = debug_query::<Pg, _>(&query).to_string();
+
+    assert!(
+        sql.contains(expected_cast),
+        "{}: Expected '{}' in SQL, got: {}",
+        test_name,
+        expected_cast,
+        sql
+    );
+}
+
 fn insert_sql_for_schema(gql: &str, entity_type_name: &str) -> String {
     use graph::components::store::write::EntityModification;
 
diff --git a/store/postgres/src/relational_queries.rs b/store/postgres/src/relational_queries.rs
index d87b950adc1..582762a2c1b 100644
--- a/store/postgres/src/relational_queries.rs
+++ b/store/postgres/src/relational_queries.rs
@@ -2090,7 +2090,18 @@ impl<'a> QueryFragment<Pg> for FindPossibleDeletionsQuery<'a> {
             } else {
                 out.push_sql("0 as causality_region, ");
             }
-            out.push_sql("e.id\n");
+            let pk_column = table.primary_key();
+
+            // Cast id to bytea so that every branch of the UNION has the same
+            // column type; the id can be text, bytea, or numeric depending on the
+            // entity type, and `UNION ALL` requires a common type per column.
+            match pk_column.column_type {
+                ColumnType::String => out.push_sql("e.id::bytea"),
+                ColumnType::Bytes => out.push_sql("e.id"),
+                ColumnType::Int8 => out.push_sql("e.id::text::bytea"),
+                _ => out.push_sql("e.id::bytea"),
+            }
+            out.push_sql("\n");
             out.push_sql("  from ");
             out.push_sql(table.qualified_name.as_str());
             out.push_sql(" e\n where ");