Changing TRUNCATE for a DELETE in the SetVersion Method #585
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| "github.com/golang-migrate/migrate/v4/database" | ||
| "github.com/hashicorp/go-multierror" |
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Move this line back up so imports are grouped. e.g. built-in modules -> 3rd party modules -> intra-package imports
| @@ -329,7 +324,7 @@ func (m *Mysql) SetVersion(version int, dirty bool) error { | |||
| return &database.Error{OrigErr: err, Err: "transaction start failed"} | |||
| } | |||
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| query := "TRUNCATE `" + m.config.MigrationsTable + "`" | |||
| query := "DELETE FROM `" + m.config.MigrationsTable + "`" | |||
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Did you also try a DROP + CREATE?
It seems like that was the approach MySQL took in v8.
What are the differences in behavior and performance between TRUNCATE and DELETE?
Since this table should be small, I don't expect a significant performance difference.
I don't think DELETE will create a table lock where as DROP will. Also, it looks like neither DROP or TRUNCATE can be rolledback.
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We should centralize the discussion :) . So yes, DELETE can be rolled back, and neither DROP nor TRUNCATE can as you mentioned. That's the main issue. The other issue is the performance of TRUNCATE in servers with a large buffer pool that affects 5.7 and below.
Also, delete will create a lock over all the rows in the table, but not a TABLE LOCK, if that is what you need (lock the table), you could use LOCK TABLES instead but I don't think that it is really needed because all other transactions will be waiting for the rowlock anyway.
Regards,
Martin.
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Agreed, let's keep the discussion in the issue.
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Closed in favor of #656 |
Since MySQL does not support transactions for DDLs, I have changed the TRUNCATE statement for a DELETE FROM, which is transactional.
The details are explained in issue #584