sql/postgres: support partial indexes

Author: a8m

internal/integration/testdata/postgres/index-partial.txt

@@ -0,0 +1,62 @@
+apply 1.hcl
+cmpshow users 1.sql
+
+apply 2.hcl
+cmpshow users 2.sql
+
+-- 1.hcl --
+schema "$db" {}
+
+table "users" {
+  schema = schema.$db
+  column "name" {
+    null = false
+    type = text
+  }
+  column "active" {
+    null = true
+    type = boolean
+  }
+  index "users_name" {
+    columns = [column.name]
+    where = "active"
+  }
+}
+
+-- 1.sql --
+        Table "script_index_partial.users"
+ Column |  Type   | Collation | Nullable | Default
+--------+---------+-----------+----------+---------
+ name   | text    |           | not null |
+ active | boolean |           |          |
+Indexes:
+    "users_name" btree (name) WHERE active
+
+
+-- 2.hcl --
+schema "$db" {}
+
+table "users" {
+  schema = schema.$db
+  column "name" {
+    null = false
+    type = text
+  }
+  column "active" {
+    null = true
+    type = boolean
+  }
+  index "users_name" {
+    columns = [column.name]
+    where = "active AND name <> ''"
+  }
+}
+
+-- 2.sql --
+        Table "script_index_partial.users"
+ Column |  Type   | Collation | Nullable | Default
+--------+---------+-----------+----------+---------
+ name   | text    |           | not null |
+ active | boolean |           |          |
+Indexes:
+    "users_name" btree (name) WHERE active AND name <> ''::text

sql/postgres/diff.go

@@ -115,10 +115,7 @@ func (*diff) IndexAttrChanged(from, to []schema.Attr) bool {
 		return true
 	}
 	var p1, p2 IndexPredicate
-	if sqlx.Has(from, &p1) != sqlx.Has(to, &p2) || p1.P != p2.P {
-		return true
-	}
-	return false
+	return sqlx.Has(from, &p1) != sqlx.Has(to, &p2) || (p1.P != p2.P && p1.P != sqlx.MayWrap(p2.P))
 }
 
 // IndexPartAttrChanged reports if the index-part attributes were changed.

sql/postgres/diff_test.go

@@ -190,11 +190,13 @@ func TestDiff_TableDiff(t *testing.T) {
 				{Name: "c1_index", Unique: true, Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: from.Columns[0]}}},
 				{Name: "c2_unique", Unique: true, Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: from.Columns[1]}}},
 				{Name: "c3_predicate", Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: from.Columns[1]}}},
+				{Name: "c4_predicate", Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: from.Columns[1]}}, Attrs: []schema.Attr{&IndexPredicate{P: "(c4 <> NULL)"}}},
 			}
 			to.Indexes = []*schema.Index{
 				{Name: "c1_index", Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: from.Columns[0]}}},
 				{Name: "c3_unique", Unique: true, Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: to.Columns[1]}}},
 				{Name: "c3_predicate", Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: from.Columns[1]}}, Attrs: []schema.Attr{&IndexPredicate{P: "c3 <> NULL"}}},
+				{Name: "c4_predicate", Table: from, Parts: []*schema.IndexPart{{SeqNo: 1, C: from.Columns[1]}}, Attrs: []schema.Attr{&IndexPredicate{P: "c4 <> NULL"}}},
 			}
 			return testcase{
 				name: "indexes",

sql/postgres/migrate_test.go

@@ -262,6 +262,7 @@ func TestPlanChanges(t *testing.T) {
 									},
 									Attrs: []schema.Attr{
 										&schema.Comment{Text: "comment"},
+										&IndexPredicate{P: "success"},
 									},
 								},
 							},
@@ -288,7 +289,7 @@ func TestPlanChanges(t *testing.T) {
 						Reverse: `ALTER TABLE "users" DROP COLUMN "name", DROP CONSTRAINT "name_not_empty", ADD CONSTRAINT "id_nonzero" CHECK ("id" <> 0), DROP CONSTRAINT "id_iseven", ADD CONSTRAINT "id_iseven" CHECK ("id" % 2 = 0)`,
 					},
 					{
-						Cmd:     `CREATE INDEX "id_key" ON "users" ("id" DESC)`,
+						Cmd:     `CREATE INDEX "id_key" ON "users" ("id" DESC) WHERE success`,
 						Reverse: `DROP INDEX "id_key"`,
 					},
 					{

sql/postgres/sqlspec.go

@@ -245,6 +245,13 @@ func convertIndex(spec *sqlspec.Index, parent *schema.Table) (*schema.Index, err
 		}
 		idx.Attrs = append(idx.Attrs, &IndexType{T: t})
 	}
+	if attr, ok := spec.Attr("where"); ok {
+		p, err := attr.String()
+		if err != nil {
+			return nil, err
+		}
+		idx.Attrs = append(idx.Attrs, &IndexPredicate{P: p})
+	}
 	return idx, nil
 }
 
@@ -367,6 +374,9 @@ func indexSpec(idx *schema.Index) (*sqlspec.Index, error) {
 	if i := (IndexType{}); sqlx.Has(idx.Attrs, &i) && i.T != IndexTypeBTree {
 		spec.Extra.Attrs = append(spec.Extra.Attrs, specutil.VarAttr("type", strings.ToUpper(i.T)))
 	}
+	if i := (IndexPredicate{}); sqlx.Has(idx.Attrs, &i) && i.P != "" {
+		spec.Extra.Attrs = append(spec.Extra.Attrs, specutil.VarAttr("where", i.P))
+	}
 	return spec, nil
 }
 

sql/postgres/sqlspec_test.go

@@ -56,6 +56,7 @@ table "table" {
 			table.table.column.col,
 			table.table.column.age,
 		]
+		where = "active"
 		comment = "index comment"
 	}
 	foreign_key "accounts" {
@@ -234,6 +235,7 @@ enum "account_type" {
 			Attrs: []schema.Attr{
 				&schema.Comment{Text: "index comment"},
 				&IndexType{T: IndexTypeHash},
+				&IndexPredicate{P: "active"},
 			},
 		},
 	}