Lazy open/parse of sql files

KeiichiHirobe commented 2 years ago

This is not a bug report, but a feature request. Current implementation always parse all of sql files, so may require a lot of time and memory if there are too many files or too big files in directory. But, in most of cases, we only need to parse 1~3 files because sort byId does not need content of files, it needs only the name of files. So, I think it is better to parse sql files only when we need content of files.

It seems to me that the best way to achieve this would be as follows

type Migration struct {
    Id   string
    // private field from here
    up   []string
    down []string

    disableTransactionUp   bool
    disableTransactionDown bool
    path                   string
    parsed                 bool
}

func (m *Migration) Up() []string {
    if !m.parsed {
        // call sqlparse.ParseMigration(r) and save results.
        m.parsed = true
    }
    return m.up
}

If it's okay, I can send PR.

rubenv commented 2 years ago

@KeiichiHirobe hey yes that's a good suggestion, feel free to submit a PR!

KeiichiHirobe commented 2 years ago

@rubenv Thanks for the quick reply! I'll send PR in 1-2 weeks.

KeiichiHirobe commented 2 years ago

@rubenv Thank you for waiting, I have just submitted PR. Please review https://github.com/rubenv/sql-migrate/pull/204.

rubenv / sql-migrate

Lazy open/parse of sql files #203