From 8888b82852deedc788e4a338984a6e4445bfb97f Mon Sep 17 00:00:00 2001
From: "Gerasimos (Makis) Maropoulos" <kataras2006@hotmail.com>
Date: Tue, 19 Sep 2023 12:34:30 +0300
Subject: [PATCH] CheckSchema: unique vs unique index improvement

---
 .github/workflows/ci.yml |  2 +-
 db_information.go        |  1 +
 db_information_test.go   |  2 +-
 desc/constraint.go       | 14 +++++++-------
 4 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e6bd96e..a917db1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,7 +21,7 @@ jobs:
 
     services:
       postgres:
-        image: postgres:15-alpine
+        image: postgres:16-alpine
         env:
           POSTGRES_USER: postgres
           POSTGRES_PASSWORD: admin!123
diff --git a/db_information.go b/db_information.go
index bb27fce..4f22a09 100644
--- a/db_information.go
+++ b/db_information.go
@@ -469,6 +469,7 @@ func (db *DB) ListColumns(ctx context.Context, tableNames ...string) ([]*desc.Co
 			if uniqueIndex.TableName == column.TableName {
 				for _, columnName := range uniqueIndex.Columns {
 					if columnName == column.Name {
+						column.Unique = false
 						column.UniqueIndex = uniqueIndex.IndexName
 						break uniqueIndexLoop
 					}
diff --git a/db_information_test.go b/db_information_test.go
index 2ec1fc5..d746d7d 100644
--- a/db_information_test.go
+++ b/db_information_test.go
@@ -6,7 +6,7 @@ import (
 )
 
 // This should match the CI's postgres version.
-const expectedDBVersion = "15"
+const expectedDBVersion = "16.0"
 
 func TestInformation_GetVersion(t *testing.T) {
 	db, err := openEmptyTestConnection()
diff --git a/desc/constraint.go b/desc/constraint.go
index 0523e12..6cf7a51 100644
--- a/desc/constraint.go
+++ b/desc/constraint.go
@@ -125,13 +125,13 @@ func (c *Constraint) BuildColumn(column *Column) error {
 	case PrimaryKeyConstraintType:
 		column.PrimaryKey = true
 	case UniqueConstraintType:
-		// if len(c.Unique.Columns) == 0 {
-		// 	// simple unique to itself.
-		// 	column.Unique = true
-		// } else {
-		// 	column.UniqueIndex = c.ConstraintName
-		// }
-		column.Unique = true
+		if len(c.Unique.Columns) == 0 || (len(c.Unique.Columns) == 1 && c.Unique.Columns[0] == c.ColumnName) {
+			// simple unique to itself.
+			column.Unique = true
+		} else {
+			column.UniqueIndex = c.ConstraintName
+		}
+		// column.Unique = true
 	case CheckConstraintType:
 		column.CheckConstraint = c.Check.Expression
 	case ForeignKeyConstraintType: