Concurrent index creation fails when done in a Go program - postgresql

Question

I am trying to create some concurrent indexes using the command CRETAE INDEX CONCURRENTLY ..... through migrations in my golang project. But whenever I run that particular migration it just takes infinitely long and is never executed.
I went and checked for the logs of the POSTGRES DB and found this thing:
The weird thing is only in migrations I am not able to create concurrent indexes whereas in my main.go if i just directly write code to execute the query it is executing successfully and even on golang's DB query console it is able to create a index concurrently.
Here is my migration package code:
func NewGorm(d *gorm.DB) *GORM {
return &GORM{db: d}
}
func (g *GORM) Run(m Migrator, app, name, methods string, logger log.Logger) error {
g.txn = g.db.Begin()
ds := &datastore.DataStore{ORM: g.db}
if methods == UP {
err = m.Up(ds, logger)
} else {
err = m.Down(ds, logger)
}
if err != nil {
g.rollBack()
return &errors.Response{Reason: "error encountered in running the migration", Detail: err}
}
g.commit()
return nil
}
I know it has something to do with transactions, but i also tried disabling it by passing flag SkipDefaultTransaction: true when initializing the connection with GORM but that also didn't worked and results were the same.
Please help how can i create concurrent indexes in migrations using GORM.

Answer 1

Let me try to help you with the issue. First, you should update the question with all of the source code so we can understand better what's going on and help you in a more accurate way. Anyway, I'll try to help you with what we have so far. I was able to achieve your goal with the following code:
package main
import (
"fmt"
"gorm.io/driver/postgres"
"gorm.io/gorm"
)
type Post struct {
Id int
Title string `gorm:"index:idx_concurrent,option:CONCURRENTLY"`
}
type GORM struct {
db *gorm.DB
}
func main() {
dsn := "host=localhost user=postgres password=postgres dbname=postgres port=5432 sslmode=disable"
db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
if err != nil {
panic(err)
}
db.AutoMigrate(&Post{})
m := db.Migrator()
if idxFound := m.HasIndex(&Post{}, "idx_concurrent"); !idxFound {
fmt.Println("idx missing")
return
}
fmt.Println("idx already present")
}
To achieve what you need, it should be enough to add a gorm annotation next to the field where you want to add the index (e.g. Title). In this annotation you can specify to create this index in a concurrent to avoid locking the table. Then, I used the gorm.Migrator to check for the index existence.
If you've already the table, you can simply add the annotation to the model struct definition and gorm will take care of it when you'll run the AutoMigrate method.
Thanks to this you should be able to cover all of the possible scenario you might face.
Let me know if this solves your issue or if you need something else, thanks!