Add a 'set replica identity' operation (#201)

Add support for a new **set replica identity** operation type. The new
operation looks like this:

```json
{
  "name": "29_set_replica_identity",
  "operations": [
    {
      "set_replica_identity": {
        "table": "fruits",
        "identity": {
          "type": "full"
        }
      }
    }
  ]
}
```

This sets the replica identity for the `fruits` table to `FULL`. The
other supported operation types are 'nothing', 'default', and 'index'.
If the replica identity is being set to an index, the operation looks
like:

```json
{
  "name": "29_set_replica_identity",
  "operations": [
    {
      "set_replica_identity": {
        "table": "fruits",
        "identity": {
          "type": "index",
          "index": "some_index_name"
        }
      }
    }
  ]
}
```

The replica identity is set directly on the underlying table on
operation start. This means that both versions of the table exposed in
the new and old versioned views will have the new replica identity set.

The docs have been updated with the details of the new operation
[here](https://github.com/xataio/pgroll/blob/set-replica-identity/docs/README.md#set-replica-identity).

docs/README.md

@@ -29,6 +29,7 @@
     * [Drop table](#drop-table)
     * [Raw SQL](#raw-sql)
     * [Rename table](#rename-table)
+    * [Set replica identity](#set-replica-identity)
 
 ## Concepts
 
@@ -674,6 +675,7 @@ See the [examples](../examples) directory for examples of each kind of operation
 * [Drop table](#drop-table)
 * [Raw SQL](#raw-sql)
 * [Rename table](#rename-table)
+* [Set replica identity](#set-replica-identity)
 
 ### Add column
 
@@ -1048,3 +1050,27 @@ A rename table operation renames a table.
 Example **rename table** migrations:
 
 * [04_rename_table.json](../examples/04_rename_table.json)
+
+### Set replica identity
+
+A set replica identity operation sets the replica identity for a table. 
+
+**set replica identity** operations have this structure:
+
+```json
+{
+  "set_replica_identity": {
+    "table": "name of the table",
+    "identity": {
+      "type": "full | default | nothing | index"
+      "index": "name of the index, if type is 'index'"
+    }
+  }
+}
+```
+
+:warning: A **set replica identity** operation is applied directly to the underlying table on migration start. This means that both versions of the table exposed in the old and new version schemas will have the new replica identity set. :warning:
+
+Example **set replica identity** migrations:
+
+* [29_set_replica_identity.json](../examples/29_set_replica_identity.json)

examples/29_set_replica_identity.json

@@ -0,0 +1,14 @@
+{
+  "name": "29_set_replica_identity",
+  "operations": [
+    {
+      "set_replica_identity": {
+        "table": "fruits",
+        "identity": {
+          "type": "index",
+          "index": "_pgroll_new_fruits_pkey"
+        }
+      }
+    }
+  ]
+}

pkg/migrations/errors.go

@@ -147,3 +147,12 @@ type InvalidPrimaryKeyError struct {
 func (e InvalidPrimaryKeyError) Error() string {
 	return fmt.Sprintf("primary key on table %q must be defined on exactly one column, found %d", e.Table, e.Fields)
 }
+
+type InvalidReplicaIdentityError struct {
+	Table    string
+	Identity string
+}
+
+func (e InvalidReplicaIdentityError) Error() string {
+	return fmt.Sprintf("replica identity on table %q must be one of 'NOTHING', 'DEFAULT', 'INDEX' or 'FULL', found %q", e.Table, e.Identity)
+}

pkg/migrations/op_common.go

@@ -12,16 +12,17 @@ import (
 type OpName string
 
 const (
-	OpNameCreateTable    OpName = "create_table"
-	OpNameRenameTable    OpName = "rename_table"
-	OpNameDropTable      OpName = "drop_table"
-	OpNameAddColumn      OpName = "add_column"
-	OpNameDropColumn     OpName = "drop_column"
-	OpNameAlterColumn    OpName = "alter_column"
-	OpNameCreateIndex    OpName = "create_index"
-	OpNameDropIndex      OpName = "drop_index"
-	OpNameDropConstraint OpName = "drop_constraint"
-	OpRawSQLName         OpName = "sql"
+	OpNameCreateTable        OpName = "create_table"
+	OpNameRenameTable        OpName = "rename_table"
+	OpNameDropTable          OpName = "drop_table"
+	OpNameAddColumn          OpName = "add_column"
+	OpNameDropColumn         OpName = "drop_column"
+	OpNameAlterColumn        OpName = "alter_column"
+	OpNameCreateIndex        OpName = "create_index"
+	OpNameDropIndex          OpName = "drop_index"
+	OpNameDropConstraint     OpName = "drop_constraint"
+	OpNameSetReplicaIdentity OpName = "set_replica_identity"
+	OpRawSQLName             OpName = "sql"
 
 	// Internal operation types used by `alter_column`
 	OpNameRenameColumn       OpName = "rename_column"
@@ -95,6 +96,9 @@ func (v *Operations) UnmarshalJSON(data []byte) error {
 		case OpNameDropConstraint:
 			item = &OpDropConstraint{}
 
+		case OpNameSetReplicaIdentity:
+			item = &OpSetReplicaIdentity{}
+
 		case OpNameAlterColumn:
 			item = &OpAlterColumn{}
 
@@ -172,6 +176,9 @@ func OperationName(op Operation) OpName {
 	case *OpDropConstraint:
 		return OpNameDropConstraint
 
+	case *OpSetReplicaIdentity:
+		return OpNameSetReplicaIdentity
+
 	case *OpAlterColumn:
 		return OpNameAlterColumn
 

pkg/migrations/op_common_test.go

@@ -282,6 +282,27 @@ func IndexMustNotExist(t *testing.T, db *sql.DB, schema, table, index string) {
 	}
 }
 
+func ReplicaIdentityMustBe(t *testing.T, db *sql.DB, schema, table, replicaIdentity string) {
+	t.Helper()
+
+	var actualReplicaIdentity string
+	err := db.QueryRow(`
+    SELECT c.relreplident
+    FROM pg_class c
+    JOIN pg_namespace n ON n.oid = c.relnamespace
+    WHERE c.relkind = 'r' -- regular table
+    AND n.nspname = $1
+    AND c.relname = $2;
+  `, schema, table).Scan(&actualReplicaIdentity)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if replicaIdentity != actualReplicaIdentity {
+		t.Fatalf("Expected replica identity to be %q, got %q", replicaIdentity, actualReplicaIdentity)
+	}
+}
+
 func indexExists(t *testing.T, db *sql.DB, schema, table, index string) bool {
 	t.Helper()
 

pkg/migrations/op_set_replica_identity.go

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package migrations
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"slices"
+	"strings"
+
+	"github.com/lib/pq"
+	"github.com/xataio/pgroll/pkg/schema"
+)
+
+type OpSetReplicaIdentity struct {
+	Table    string          `json:"table"`
+	Identity ReplicaIdentity `json:"identity"`
+}
+
+type ReplicaIdentity struct {
+	Type  string `json:"type"`
+	Index string `json:"index"`
+}
+
+var _ Operation = (*OpSetReplicaIdentity)(nil)
+
+func (o *OpSetReplicaIdentity) Start(ctx context.Context, conn *sql.DB, stateSchema string, s *schema.Schema, cbs ...CallbackFn) error {
+	// build the correct form of the `SET REPLICA IDENTITY` statement based on the`identity type
+	identitySQL := strings.ToUpper(o.Identity.Type)
+	if identitySQL == "INDEX" {
+		identitySQL = fmt.Sprintf("USING INDEX %s", pq.QuoteIdentifier(o.Identity.Index))
+	}
+
+	// set the replica identity on the underlying table
+	_, err := conn.ExecContext(ctx, fmt.Sprintf("ALTER TABLE %s REPLICA IDENTITY %s", o.Table, identitySQL))
+	return err
+}
+
+func (o *OpSetReplicaIdentity) Complete(ctx context.Context, conn *sql.DB) error {
+	// No-op
+	return nil
+}
+
+func (o *OpSetReplicaIdentity) Rollback(ctx context.Context, conn *sql.DB) error {
+	// No-op
+	return nil
+}
+
+func (o *OpSetReplicaIdentity) Validate(ctx context.Context, s *schema.Schema) error {
+	identityType := strings.ToUpper(o.Identity.Type)
+
+	table := s.GetTable(o.Table)
+	if table == nil {
+		return TableDoesNotExistError{Name: o.Table}
+	}
+
+	identities := []string{"NOTHING", "DEFAULT", "INDEX", "FULL"}
+	if !slices.Contains(identities, identityType) {
+		return InvalidReplicaIdentityError{Table: o.Table, Identity: o.Identity.Type}
+	}
+
+	if identityType == "INDEX" {
+		if _, ok := table.Indexes[o.Identity.Index]; !ok {
+			return IndexDoesNotExistError{Name: o.Identity.Index}
+		}
+	}
+
+	return nil
+}