Correct Strategy for DB migrations in Go












1















We have a go app where we use Postgres as a backend DB.
We use https://github.com/jmoiron/sqlx for communicating with DB.
The code to read all rows from a table is as belows:



 rows, err := repo.db.Queryx(ListNodesQuery)
if err != nil {
repo.logger.Log("method", "ListNodes", "error", err)
return nil, err
}

r := *Node{}
for rows.Next() {
var n Node
err = rows.StructScan(&n)
}


After adding a new column in the DB, the code as expected errs as below



missing destination name type in *Node


as db table has more columns. Making change in code to update the struct simultaneously is ofcourse not possible.



I see that one way to turn this err off is to use db.Unsafe as documented here



Is there any other idiomatic way to deal with this situation?










share|improve this question























  • Are you using a variant on SELECT * FROM... to query from the table? Change this to explicitly list the column names of interest. You save wasting database and network resources in moving data you discard, and you can explicitly update the query at the point the code is ready to receive values from the additional columns.

    – Cosmic Ossifrage
    Nov 15 '18 at 10:58











  • hmm...good point

    – Saurav Prakash
    Nov 15 '18 at 11:24
















1















We have a go app where we use Postgres as a backend DB.
We use https://github.com/jmoiron/sqlx for communicating with DB.
The code to read all rows from a table is as belows:



 rows, err := repo.db.Queryx(ListNodesQuery)
if err != nil {
repo.logger.Log("method", "ListNodes", "error", err)
return nil, err
}

r := *Node{}
for rows.Next() {
var n Node
err = rows.StructScan(&n)
}


After adding a new column in the DB, the code as expected errs as below



missing destination name type in *Node


as db table has more columns. Making change in code to update the struct simultaneously is ofcourse not possible.



I see that one way to turn this err off is to use db.Unsafe as documented here



Is there any other idiomatic way to deal with this situation?










share|improve this question























  • Are you using a variant on SELECT * FROM... to query from the table? Change this to explicitly list the column names of interest. You save wasting database and network resources in moving data you discard, and you can explicitly update the query at the point the code is ready to receive values from the additional columns.

    – Cosmic Ossifrage
    Nov 15 '18 at 10:58











  • hmm...good point

    – Saurav Prakash
    Nov 15 '18 at 11:24














1












1








1








We have a go app where we use Postgres as a backend DB.
We use https://github.com/jmoiron/sqlx for communicating with DB.
The code to read all rows from a table is as belows:



 rows, err := repo.db.Queryx(ListNodesQuery)
if err != nil {
repo.logger.Log("method", "ListNodes", "error", err)
return nil, err
}

r := *Node{}
for rows.Next() {
var n Node
err = rows.StructScan(&n)
}


After adding a new column in the DB, the code as expected errs as below



missing destination name type in *Node


as db table has more columns. Making change in code to update the struct simultaneously is ofcourse not possible.



I see that one way to turn this err off is to use db.Unsafe as documented here



Is there any other idiomatic way to deal with this situation?










share|improve this question














We have a go app where we use Postgres as a backend DB.
We use https://github.com/jmoiron/sqlx for communicating with DB.
The code to read all rows from a table is as belows:



 rows, err := repo.db.Queryx(ListNodesQuery)
if err != nil {
repo.logger.Log("method", "ListNodes", "error", err)
return nil, err
}

r := *Node{}
for rows.Next() {
var n Node
err = rows.StructScan(&n)
}


After adding a new column in the DB, the code as expected errs as below



missing destination name type in *Node


as db table has more columns. Making change in code to update the struct simultaneously is ofcourse not possible.



I see that one way to turn this err off is to use db.Unsafe as documented here



Is there any other idiomatic way to deal with this situation?







sql postgresql go sqlx






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 15 '18 at 10:53









Saurav PrakashSaurav Prakash

982413




982413













  • Are you using a variant on SELECT * FROM... to query from the table? Change this to explicitly list the column names of interest. You save wasting database and network resources in moving data you discard, and you can explicitly update the query at the point the code is ready to receive values from the additional columns.

    – Cosmic Ossifrage
    Nov 15 '18 at 10:58











  • hmm...good point

    – Saurav Prakash
    Nov 15 '18 at 11:24



















  • Are you using a variant on SELECT * FROM... to query from the table? Change this to explicitly list the column names of interest. You save wasting database and network resources in moving data you discard, and you can explicitly update the query at the point the code is ready to receive values from the additional columns.

    – Cosmic Ossifrage
    Nov 15 '18 at 10:58











  • hmm...good point

    – Saurav Prakash
    Nov 15 '18 at 11:24

















Are you using a variant on SELECT * FROM... to query from the table? Change this to explicitly list the column names of interest. You save wasting database and network resources in moving data you discard, and you can explicitly update the query at the point the code is ready to receive values from the additional columns.

– Cosmic Ossifrage
Nov 15 '18 at 10:58





Are you using a variant on SELECT * FROM... to query from the table? Change this to explicitly list the column names of interest. You save wasting database and network resources in moving data you discard, and you can explicitly update the query at the point the code is ready to receive values from the additional columns.

– Cosmic Ossifrage
Nov 15 '18 at 10:58













hmm...good point

– Saurav Prakash
Nov 15 '18 at 11:24





hmm...good point

– Saurav Prakash
Nov 15 '18 at 11:24












1 Answer
1






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oldest

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0















Making change in code to update the struct simultaneously is ofcourse
not possible.




You can manage DB schemas inside your codebase and have some app startup code that automatically migrates DB to latest schema version to keep code and DB in sync.



One of the options is github.com/golang-migrate.



Run this code on app start to update DB schema to latest version:



migrate, err := migrate.New("folder to sql scrips", "db connection string")
if err != nil {
logger.Panic(err)
}
err = migrate.Up()
if err != nil {
logger.Panic(err)
}





share|improve this answer
























  • But If I have to rollback, then again I have to make change in code to update the struct.

    – Saurav Prakash
    Nov 18 '18 at 8:29











  • You have to keep your DB schema and code schema in sync. Adding/removing columns is just one of many cases how that schema evolves. GO idiomatically wants to handle all errors including mapping explicitly. You are fighting with language intent when you want to swallow mapping inconsistencies.

    – Dmitry Harnitski
    Nov 18 '18 at 13:54











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0















Making change in code to update the struct simultaneously is ofcourse
not possible.




You can manage DB schemas inside your codebase and have some app startup code that automatically migrates DB to latest schema version to keep code and DB in sync.



One of the options is github.com/golang-migrate.



Run this code on app start to update DB schema to latest version:



migrate, err := migrate.New("folder to sql scrips", "db connection string")
if err != nil {
logger.Panic(err)
}
err = migrate.Up()
if err != nil {
logger.Panic(err)
}





share|improve this answer
























  • But If I have to rollback, then again I have to make change in code to update the struct.

    – Saurav Prakash
    Nov 18 '18 at 8:29











  • You have to keep your DB schema and code schema in sync. Adding/removing columns is just one of many cases how that schema evolves. GO idiomatically wants to handle all errors including mapping explicitly. You are fighting with language intent when you want to swallow mapping inconsistencies.

    – Dmitry Harnitski
    Nov 18 '18 at 13:54
















0















Making change in code to update the struct simultaneously is ofcourse
not possible.




You can manage DB schemas inside your codebase and have some app startup code that automatically migrates DB to latest schema version to keep code and DB in sync.



One of the options is github.com/golang-migrate.



Run this code on app start to update DB schema to latest version:



migrate, err := migrate.New("folder to sql scrips", "db connection string")
if err != nil {
logger.Panic(err)
}
err = migrate.Up()
if err != nil {
logger.Panic(err)
}





share|improve this answer
























  • But If I have to rollback, then again I have to make change in code to update the struct.

    – Saurav Prakash
    Nov 18 '18 at 8:29











  • You have to keep your DB schema and code schema in sync. Adding/removing columns is just one of many cases how that schema evolves. GO idiomatically wants to handle all errors including mapping explicitly. You are fighting with language intent when you want to swallow mapping inconsistencies.

    – Dmitry Harnitski
    Nov 18 '18 at 13:54














0












0








0








Making change in code to update the struct simultaneously is ofcourse
not possible.




You can manage DB schemas inside your codebase and have some app startup code that automatically migrates DB to latest schema version to keep code and DB in sync.



One of the options is github.com/golang-migrate.



Run this code on app start to update DB schema to latest version:



migrate, err := migrate.New("folder to sql scrips", "db connection string")
if err != nil {
logger.Panic(err)
}
err = migrate.Up()
if err != nil {
logger.Panic(err)
}





share|improve this answer














Making change in code to update the struct simultaneously is ofcourse
not possible.




You can manage DB schemas inside your codebase and have some app startup code that automatically migrates DB to latest schema version to keep code and DB in sync.



One of the options is github.com/golang-migrate.



Run this code on app start to update DB schema to latest version:



migrate, err := migrate.New("folder to sql scrips", "db connection string")
if err != nil {
logger.Panic(err)
}
err = migrate.Up()
if err != nil {
logger.Panic(err)
}






share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 15 '18 at 13:39









Dmitry HarnitskiDmitry Harnitski

3,85311834




3,85311834













  • But If I have to rollback, then again I have to make change in code to update the struct.

    – Saurav Prakash
    Nov 18 '18 at 8:29











  • You have to keep your DB schema and code schema in sync. Adding/removing columns is just one of many cases how that schema evolves. GO idiomatically wants to handle all errors including mapping explicitly. You are fighting with language intent when you want to swallow mapping inconsistencies.

    – Dmitry Harnitski
    Nov 18 '18 at 13:54



















  • But If I have to rollback, then again I have to make change in code to update the struct.

    – Saurav Prakash
    Nov 18 '18 at 8:29











  • You have to keep your DB schema and code schema in sync. Adding/removing columns is just one of many cases how that schema evolves. GO idiomatically wants to handle all errors including mapping explicitly. You are fighting with language intent when you want to swallow mapping inconsistencies.

    – Dmitry Harnitski
    Nov 18 '18 at 13:54

















But If I have to rollback, then again I have to make change in code to update the struct.

– Saurav Prakash
Nov 18 '18 at 8:29





But If I have to rollback, then again I have to make change in code to update the struct.

– Saurav Prakash
Nov 18 '18 at 8:29













You have to keep your DB schema and code schema in sync. Adding/removing columns is just one of many cases how that schema evolves. GO idiomatically wants to handle all errors including mapping explicitly. You are fighting with language intent when you want to swallow mapping inconsistencies.

– Dmitry Harnitski
Nov 18 '18 at 13:54





You have to keep your DB schema and code schema in sync. Adding/removing columns is just one of many cases how that schema evolves. GO idiomatically wants to handle all errors including mapping explicitly. You are fighting with language intent when you want to swallow mapping inconsistencies.

– Dmitry Harnitski
Nov 18 '18 at 13:54




















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