Generator: add an option to skip partitions

[MassimilianoPoggiQonto]

Currently if you have partitioned tables, with partitions residing on the same schema as your tables, jet will generate schemas for each partition individually.

It would be great if an --ignore-partitions flag could be added so that partitions are not included for generation.

[go-jet]

Different developers use various naming templates for partitions, so there's no single universal solution to exclude partition tables from generation.
You can customize generator to skip unwanted tables.

[MassimilianoPoggiQonto]

MSSql can rely on sys.partitions and Postgres can rely on pg_class.relispartition to identify partitions.

[go-jet]

Yeah, it seems you're right. We could add generator flag to handle this use case.

[lkzcover]

I’m trying to do it in the custom postgres.GenerateDSN() method. It works for the model package, but I haven’t understood how to skip partitions in the table package yet, because I can’t find a way to filter schemaMetadata in template.ProcessSchema yet.

Example:

func isPartitionTable(db *sql.DB, tableName string) bool {
	var count int
	err := db.QueryRow(`
		SELECT COUNT(*)
		FROM pg_inherits
		JOIN pg_class c ON pg_inherits.inhrelid = c.oid
		WHERE c.relname = $1`, tableName).Scan(&count)

	if err != nil {
		log.Fatal(err.Error())
	}
	return count > 0
}

err = postgres.GenerateDSN(
	dsn,
	schema,
	path,
	template.Default(postgres2.Dialect).
		UseSchema(func(schemaMetaData metadata.Schema) template.Schema {
			return template.DefaultSchema(schemaMetaData).
				UseModel(template.DefaultModel().
					UseTable(func(table metadata.Table) template.TableModel {
						if isPartitionTable(db, table.Name) {
							return template.TableModel{Skip: true}
						}
						...
					}),
				)
		}),
)