columns are dropped and recreated at server start using oracle db

Issue type:

[ ] question [x] bug report [ ] feature request [ ] documentation issue

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [ ] mysql / mariadb [x] oracle [ ] postgres [ ] cockroachdb [x] sqlite [ ] sqljs [ ] react-native [ ] expo

TypeORM version:

[x] latest [ ] @next [ ] 0.x.x (or put your version here)

Steps to reproduce or a small repository showing the problem:

We use sqlite for our local development and an oracle db for our deployed versions. When we start the server the first time using our oracle db everything works fine. All the tables are created. But when we start it a second time, typeorm says the columns changed, even though they didn’t, and drops all the constraints/columns and re-creates them right afterwards.

columns changed in "users". updating: id, createdBy, updatedBy, name
query: ALTER TABLE "users" DROP CONSTRAINT "PK_a3ffb1c0c8416b9fc6f907b7433"
query: ALTER TABLE "users" DROP COLUMN "id"
query: ALTER TABLE "users" ADD "id" varchar2(255) NOT NULL
query: ALTER TABLE "users" ADD CONSTRAINT "PK_a3ffb1c0c8416b9fc6f907b7433" PRIMARY KEY ("id")

This obviously leads to data loss and since it’s deleting/recreating column by column it messes up the oracle db and leads to following error as soon as data is inserted: QueryFailedError: ORA-01758: table must be empty to add mandatory (NOT NULL) column

if we use exactly the same configuration in an sqlite setup nothing like this happens and the db starts up without dropping any columns.

I set up a small project to recreate the issue: https://github.com/Gnilherk/typeormapp

[ataquino]

I had a similar issue with mssql, columns with { type: 'varchar', length: 'max' } were always dropped and created, even when generating migrations. By looking at the migration file, I saw the up() method was creating the column with type varchar(max) and the down() method was creating it as varchar(MAX). So I changed length: 'max' to length: 'MAX' and the problem went away.

Maybe something similar is happening in these other cases?

[hsharghi]

Same here using it with sqlite. I see some strange behavior in addition to dropping tables, like:

renaming column "department" in to "department"

Anyone found a way to fix it?

Update: Models with column type simple-enum will cause type-orm to drop and recreate the table