[postgres] Improve performance when adding many new fields to the Schema (#3740)

spec/Schema.spec.js

@@ -181,7 +181,7 @@ describe('SchemaController', () => {
   it('can add classes without needing an object', done => {
     config.database.loadSchema()
     .then(schema => schema.addClassIfNotExists('NewClass', {
-      foo: {type: 'String'}
+      foo: {type: 'String'},
     }))
     .then(actualSchema => {
       const expectedSchema = {
@@ -210,6 +210,81 @@ describe('SchemaController', () => {
     });
   });
 
+  it('can update classes without needing an object', done => {
+    const levelPermissions = {
+      find: { '*': true },
+      get: { '*': true },
+      create: { '*': true },
+      update: { '*': true },
+      delete: { '*': true },
+      addField: { '*': true },
+    };
+    config.database.loadSchema()
+      .then(schema => {
+        schema.validateObject('NewClass', { foo: 2 })
+          .then(() => schema.reloadData())
+          .then(() => schema.updateClass('NewClass', {
+            fooOne: {type: 'Number'},
+            fooTwo: {type: 'Array'},
+            fooThree: {type: 'Date'},
+            fooFour: {type: 'Object'},
+            fooFive: {type: 'Relation', targetClass: '_User' },
+            fooSix: {type: 'String'},
+            fooSeven: {type: 'Object' },
+            fooEight: {type: 'String'},
+            fooNine: {type: 'String'},
+            fooTeen: {type: 'Number' },
+            fooEleven: {type: 'String'},
+            fooTwelve: {type: 'String'},
+            fooThirteen: {type: 'String'},
+            fooFourteen: {type: 'String'},
+            fooFifteen: {type: 'String'},
+            fooSixteen: {type: 'String'},
+            fooEighteen: {type: 'String'},
+            fooNineteen: {type: 'String'},
+          }, levelPermissions, config.database))
+          .then(actualSchema => {
+            const expectedSchema = {
+              className: 'NewClass',
+              fields: {
+                objectId: { type: 'String' },
+                updatedAt: { type: 'Date' },
+                createdAt: { type: 'Date' },
+                ACL: { type: 'ACL' },
+                foo: { type: 'Number' },
+                fooOne: {type: 'Number'},
+                fooTwo: {type: 'Array'},
+                fooThree: {type: 'Date'},
+                fooFour: {type: 'Object'},
+                fooFive: {type: 'Relation', targetClass: '_User' },
+                fooSix: {type: 'String'},
+                fooSeven: {type: 'Object' },
+                fooEight: {type: 'String'},
+                fooNine: {type: 'String'},
+                fooTeen: {type: 'Number' },
+                fooEleven: {type: 'String'},
+                fooTwelve: {type: 'String'},
+                fooThirteen: {type: 'String'},
+                fooFourteen: {type: 'String'},
+                fooFifteen: {type: 'String'},
+                fooSixteen: {type: 'String'},
+                fooEighteen: {type: 'String'},
+                fooNineteen: {type: 'String'},
+              },
+              classLevelPermissions: { ...levelPermissions },
+            };
+
+            expect(dd(actualSchema, expectedSchema)).toEqual(undefined);
+            done();
+          })
+          .catch(error => {
+            console.trace(error);
+            done();
+            fail('Error creating class: ' + JSON.stringify(error));
+          });
+      });
+  });
+
   it('will fail to create a class if that class was already created by an object', done => {
     config.database.loadSchema()
       .then(schema => {

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -543,15 +543,15 @@ export class PostgresStorageAdapter {
         promise = t.none('CREATE TABLE IF NOT EXISTS $<joinTable:name> ("relatedId" varChar(120), "owningId" varChar(120), PRIMARY KEY("relatedId", "owningId") )', {joinTable: `_Join:${fieldName}:${className}`})
       }
       return promise.then(() => {
-        return t.any('SELECT "schema" FROM "_SCHEMA" WHERE "className" = $<className>', {className});
+        return t.any('SELECT "schema" FROM "_SCHEMA" WHERE "className" = $<className> and ("schema"::json->\'fields\'->$<fieldName>) is not null', {className, fieldName});
       }).then(result => {
-        if (fieldName in result[0].schema.fields) {
+        if (result[0]) {
           throw "Attempted to add a field that already exists";
         } else {
-          result[0].schema.fields[fieldName] = type;
+          const path = `{fields,${fieldName}}`;
           return t.none(
-            'UPDATE "_SCHEMA" SET "schema"=$<schema> WHERE "className"=$<className>',
+            'UPDATE "_SCHEMA" SET "schema"=jsonb_set("schema", $<path>, $<type>)  WHERE "className"=$<className>',
-            {schema: result[0].schema, className}
+            { path, type, className }
           );
         }
       });