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feat: support mutations #43

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merged 3 commits into from
Oct 5, 2021
Merged

feat: support mutations #43

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7a0f911
feat: support mutations
olavloite Sep 29, 2021
2d2cc26
chore: address review comments
olavloite Oct 5, 2021
3f3ecba
chore: address last review comment
olavloite Oct 5, 2021
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32 changes: 32 additions & 0 deletions driver.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -201,6 +201,18 @@ func (c *connector) Driver() driver.Driver {
return &Driver{}
}

type SpannerConn interface {
// Apply writes an array of mutations to the database. This method may only be called while the connection
// is outside a transaction. Use BufferWrite to write mutations in a transaction.
// See also spanner.Client#Apply
Apply(ctx context.Context, ms []*spanner.Mutation, opts ...spanner.ApplyOption) (commitTimestamp time.Time, err error)

// BufferWrite writes an array of mutations to the current transaction. This method may only be called while the
// connection is in a read/write transaction. Use Apply to write mutations outside a transaction.
// See also spanner.ReadWriteTransaction#BufferWrite
BufferWrite(ms []*spanner.Mutation) error
}

type conn struct {
closed bool
client *spanner.Client
Expand All @@ -210,6 +222,26 @@ type conn struct {
retryAborts bool
}

func (c *conn) Apply(ctx context.Context, ms []*spanner.Mutation, opts ...spanner.ApplyOption) (commitTimestamp time.Time, err error) {
if c.inTransaction() {
return time.Time{}, spanner.ToSpannerError(
status.Error(
codes.FailedPrecondition,
"Apply may not be called while the connection is in a transaction. Use BufferWrite to write mutations in a transaction."))
}
return c.client.Apply(ctx, ms, opts...)
}

func (c *conn) BufferWrite(ms []*spanner.Mutation) error {
if !c.inTransaction() {
return spanner.ToSpannerError(
status.Error(
codes.FailedPrecondition,
"BufferWrite may not be called while the connection is not in a transaction. Use Apply to write mutations outside a transaction."))
}
return c.tx.BufferWrite(ms)
}

// Ping implements the driver.Pinger interface.
// returns ErrBadConn if the connection is no longer valid.
func (c *conn) Ping(ctx context.Context) error {
Expand Down
139 changes: 139 additions & 0 deletions driver_with_mockserver_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1020,6 +1020,145 @@ func TestPrepare(t *testing.T) {
}
}

func TestApplyMutations(t *testing.T) {
t.Parallel()

ctx := context.Background()
db, server, teardown := setupTestDBConnection(t)
defer teardown()

con, err := db.Conn(ctx)
if err != nil {
t.Fatalf("failed to get connection: %v", err)
}
var commitTimestamp time.Time
if err := con.Raw(func(driverConn interface{}) error {
spannerConn, ok := driverConn.(SpannerConn)
if !ok {
return fmt.Errorf("unexpected driver connection %v, expected SpannerConn", driverConn)
}
commitTimestamp, err = spannerConn.Apply(ctx, []*spanner.Mutation{
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(1), "Foo", int64(50)}),
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(2), "Bar", int64(1)}),
})
return err
}); err != nil {
t.Fatalf("failed to apply mutations: %v", err)
}
if commitTimestamp.Equal(time.Time{}) {
t.Fatal("no commit timestamp returned")
}

// Even though the Apply method is used outside a transaction, the connection will internally start a read/write
// transaction for the mutations.
requests := drainRequestsFromServer(server.TestSpanner)
commitRequests := requestsOfType(requests, reflect.TypeOf(&sppb.CommitRequest{}))
if g, w := len(commitRequests), 1; g != w {
t.Fatalf("commit requests count mismatch\nGot: %v\nWant: %v", g, w)
}
commitRequest := commitRequests[0].(*sppb.CommitRequest)
if g, w := len(commitRequest.Mutations), 2; g != w {
t.Fatalf("mutation count mismatch\nGot: %v\nWant: %v", g, w)
}
}

func TestApplyFailsInTransaction(t *testing.T) {
t.Parallel()

ctx := context.Background()
db, _, teardown := setupTestDBConnection(t)
defer teardown()

con, err := db.Conn(ctx)
if err != nil {
t.Fatalf("failed to get connection: %v", err)
}
_, err = con.BeginTx(ctx, &sql.TxOptions{})
if err != nil {
t.Fatalf("failed to begin transaction: %v", err)
}
if g, w := spanner.ErrCode(con.Raw(func(driverConn interface{}) error {
spannerConn, ok := driverConn.(SpannerConn)
if !ok {
return fmt.Errorf("unexpected driver connection %v, expected SpannerConn", driverConn)
}
_, err = spannerConn.Apply(ctx, []*spanner.Mutation{
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(1), "Foo", int64(50)}),
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(2), "Bar", int64(1)}),
})
return err
})), codes.FailedPrecondition; g != w {
t.Fatalf("error code mismatch for Apply during transaction\nGot: %v\nWant: %v", g, w)
}
}

func TestBufferWriteMutations(t *testing.T) {
t.Parallel()

ctx := context.Background()
db, server, teardown := setupTestDBConnection(t)
defer teardown()

con, err := db.Conn(ctx)
if err != nil {
t.Fatalf("failed to get connection: %v", err)
}
tx, err := con.BeginTx(ctx, &sql.TxOptions{})
if err != nil {
t.Fatalf("failed to begin transaction: %v", err)
}
if err := con.Raw(func(driverConn interface{}) error {
spannerConn, ok := driverConn.(SpannerConn)
if !ok {
return fmt.Errorf("unexpected driver connection %v, expected SpannerConn", driverConn)
}
return spannerConn.BufferWrite([]*spanner.Mutation{
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(1), "Foo", int64(50)}),
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(2), "Bar", int64(1)}),
})
}); err != nil {
t.Fatalf("failed to buffer mutations: %v", err)
}
if err := tx.Commit(); err != nil {
t.Fatalf("failed to commit transaction: %v", err)
}

requests := drainRequestsFromServer(server.TestSpanner)
commitRequests := requestsOfType(requests, reflect.TypeOf(&sppb.CommitRequest{}))
if g, w := len(commitRequests), 1; g != w {
t.Fatalf("commit requests count mismatch\nGot: %v\nWant: %v", g, w)
}
commitRequest := commitRequests[0].(*sppb.CommitRequest)
if g, w := len(commitRequest.Mutations), 2; g != w {
t.Fatalf("mutation count mismatch\nGot: %v\nWant: %v", g, w)
}
}

func TestBufferWriteFailsOutsideTransaction(t *testing.T) {
t.Parallel()

ctx := context.Background()
db, _, teardown := setupTestDBConnection(t)
defer teardown()

con, err := db.Conn(ctx)
if err != nil {
t.Fatalf("failed to get connection: %v", err)
}
if g, w := spanner.ErrCode(con.Raw(func(driverConn interface{}) error {
spannerConn, ok := driverConn.(SpannerConn)
if !ok {
return fmt.Errorf("unexpected driver connection %v, expected SpannerConn", driverConn)
}
return spannerConn.BufferWrite([]*spanner.Mutation{
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(1), "Foo", int64(50)}),
spanner.Insert("Accounts", []string{"AccountId", "Nickname", "Balance"}, []interface{}{int64(2), "Bar", int64(1)}),
})
})), codes.FailedPrecondition; g != w {
t.Fatalf("error code mismatch for BufferWrite outside transaction\nGot: %v\nWant: %v", g, w)
}
}

func TestPing(t *testing.T) {
t.Parallel()

Expand Down
4 changes: 2 additions & 2 deletions examples/go.mod
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,13 @@ go 1.14
replace github.com/cloudspannerecosystem/go-sql-spanner => ../

require (
cloud.google.com/go/spanner v1.23.1-0.20210727075241-3d6c6c7873e1
cloud.google.com/go/spanner v1.25.0
github.com/cloudspannerecosystem/go-sql-spanner v0.0.0-00010101000000-000000000000
github.com/containerd/containerd v1.5.5 // indirect
github.com/docker/docker v20.10.8+incompatible
github.com/docker/go-connections v0.4.0
github.com/gorilla/mux v1.8.0 // indirect
github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6 // indirect
github.com/morikuni/aec v1.0.0 // indirect
google.golang.org/genproto v0.0.0-20210726143408-b02e89920bf0
google.golang.org/genproto v0.0.0-20210821163610-241b8fcbd6c8
)
20 changes: 20 additions & 0 deletions examples/go.sum
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,9 @@ cloud.google.com/go v0.84.0/go.mod h1:RazrYuxIK6Kb7YrzzhPoLmCVzl7Sup4NrbKPg8KHSU
cloud.google.com/go v0.87.0/go.mod h1:TpDYlFy7vuLzZMMZ+B6iRiELaY7z/gJPaqbMx6mlWcY=
cloud.google.com/go v0.88.0 h1:MZ2cf9Elnv1wqccq8ooKO2MqHQLc+ChCp/+QWObCpxg=
cloud.google.com/go v0.88.0/go.mod h1:dnKwfYbP9hQhefiUvpbcAyoGSHUrOxR20JVElLiUvEY=
cloud.google.com/go v0.90.0/go.mod h1:kRX0mNRHe0e2rC6oNakvwQqzyDmg57xJ+SZU1eT2aDQ=
cloud.google.com/go v0.93.3 h1:wPBktZFzYBcCZVARvwVKqH1uEj+aLXofJEtrb4oOsio=
cloud.google.com/go v0.93.3/go.mod h1:8utlLll2EF5XMAV15woO4lSbWQlk8rer9aLOfLh7+YI=
cloud.google.com/go/bigquery v1.0.1/go.mod h1:i/xbL2UlR5RvWAURpBYZTtm/cXjCha9lbfbpx4poX+o=
cloud.google.com/go/bigquery v1.3.0/go.mod h1:PjpwJnslEMmckchkHFfq+HTD2DmtT67aNFKH1/VBDHE=
cloud.google.com/go/bigquery v1.4.0/go.mod h1:S8dzgnTigyfTmLBfrtrhyYhwRxG72rYxvftPBK2Dvzc=
Expand All @@ -38,6 +41,8 @@ cloud.google.com/go/pubsub v1.2.0/go.mod h1:jhfEVHT8odbXTkndysNHCcx0awwzvfOlguIA
cloud.google.com/go/pubsub v1.3.1/go.mod h1:i+ucay31+CNRpDW4Lu78I4xXG+O1r/MAHgjpRVR+TSU=
cloud.google.com/go/spanner v1.23.1-0.20210727075241-3d6c6c7873e1 h1:DOK5uvDxxzkTjLIb7xt15zWewNS66DnrOmOb2Hv7C9g=
cloud.google.com/go/spanner v1.23.1-0.20210727075241-3d6c6c7873e1/go.mod h1:EZI0yH1D/PrXK0XH9Ba5LGXTXWeqZv0ClOD/19a0Z58=
cloud.google.com/go/spanner v1.25.0 h1:oBLJVlW/v3QMntbpUavhneJEQyPcxbAY5+rI+Jv9hvE=
cloud.google.com/go/spanner v1.25.0/go.mod h1:kQUft3x355hzzaeFbObjsvkzZDgpDkesp3v75WBnI8w=
cloud.google.com/go/storage v1.0.0/go.mod h1:IhtSnM/ZTZV8YYJWCY8RULGVqBDmpoyjwiyrjsg+URw=
cloud.google.com/go/storage v1.5.0/go.mod h1:tpKbwo567HUNpVclU5sGELwQWBDZ8gh0ZeosJ0Rtdos=
cloud.google.com/go/storage v1.6.0/go.mod h1:N7U0C8pVQ/+NIKOBQyamJIeKQKkZ+mxpohlUTyfDhBk=
Expand Down Expand Up @@ -385,6 +390,7 @@ github.com/google/pprof v0.0.0-20210226084205-cbba55b83ad5/go.mod h1:kpwsk12EmLe
github.com/google/pprof v0.0.0-20210601050228-01bbb1931b22/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
github.com/google/pprof v0.0.0-20210609004039-a478d1d731e9/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
github.com/google/pprof v0.0.0-20210715191844-86eeefc3e471/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
github.com/google/pprof v0.0.0-20210720184732-4bb14d4b1be1/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
github.com/google/uuid v1.0.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
Expand Down Expand Up @@ -777,6 +783,8 @@ golang.org/x/oauth2 v0.0.0-20210313182246-cd4f82c27b84/go.mod h1:KelEdhl1UZF7XfJ
golang.org/x/oauth2 v0.0.0-20210514164344-f6687ab2804c/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
golang.org/x/oauth2 v0.0.0-20210628180205-a41e5a781914 h1:3B43BWw0xEBsLZ/NO1VALz6fppU3481pik+2Ksv45z8=
golang.org/x/oauth2 v0.0.0-20210628180205-a41e5a781914/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
golang.org/x/oauth2 v0.0.0-20210805134026-6f1e6394065a h1:4Kd8OPUx1xgUwrHDaviWZO8MsgoZTZYC3g+8m16RBww=
golang.org/x/oauth2 v0.0.0-20210805134026-6f1e6394065a/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
Expand Down Expand Up @@ -869,6 +877,8 @@ golang.org/x/sys v0.0.0-20210603125802-9665404d3644/go.mod h1:oPkhp1MJrh7nUepCBc
golang.org/x/sys v0.0.0-20210616094352-59db8d763f22/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c h1:F1jZWGFhYfh0Ci55sIpILtKKK8p3i2/krTr0H1rg74I=
golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069 h1:siQdpVirKtzPhKl3lZWozZraCFObP8S1v6PRp0bLrtU=
golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
Expand Down Expand Up @@ -976,6 +986,8 @@ google.golang.org/api v0.48.0/go.mod h1:71Pr1vy+TAZRPkPs/xlCf5SsU8WjuAWv1Pfjbtuk
google.golang.org/api v0.50.0/go.mod h1:4bNT5pAuq5ji4SRZm+5QIkjny9JAyVD/3gaSihNefaw=
google.golang.org/api v0.51.0 h1:SQaA2Cx57B+iPw2MBgyjEkoeMkRK2IenSGoia0U3lCk=
google.golang.org/api v0.51.0/go.mod h1:t4HdrdoNgyN5cbEfm7Lum0lcLDLiise1F8qDKX00sOU=
google.golang.org/api v0.54.0 h1:ECJUVngj71QI6XEm7b1sAf8BljU5inEhMbKPR8Lxhhk=
google.golang.org/api v0.54.0/go.mod h1:7C4bFFOvVDGXjfDTAsgGwDgAxRDeQ4X8NvUedIt6z3k=
google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
google.golang.org/appengine v1.5.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
Expand Down Expand Up @@ -1038,6 +1050,11 @@ google.golang.org/genproto v0.0.0-20210716133855-ce7ef5c701ea/go.mod h1:AxrInvYm
google.golang.org/genproto v0.0.0-20210721163202-f1cecdd8b78a/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
google.golang.org/genproto v0.0.0-20210726143408-b02e89920bf0 h1:tcs4DyF9LYv8cynRAbX8JeBpuezJLaK6RfiATAsGwnY=
google.golang.org/genproto v0.0.0-20210726143408-b02e89920bf0/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
google.golang.org/genproto v0.0.0-20210728212813-7823e685a01f/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
google.golang.org/genproto v0.0.0-20210805201207-89edb61ffb67/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
google.golang.org/genproto v0.0.0-20210813162853-db860fec028c/go.mod h1:cFeNkxwySK631ADgubI+/XFU/xp8FD5KIVV4rj8UC5w=
google.golang.org/genproto v0.0.0-20210821163610-241b8fcbd6c8 h1:XosVttQUxX8erNhEruTu053/VchgYuksoS9Bj/OITjU=
google.golang.org/genproto v0.0.0-20210821163610-241b8fcbd6c8/go.mod h1:eFjDcFEctNawg4eG61bRv87N7iHBWyVhJu7u1kqDUXY=
google.golang.org/grpc v0.0.0-20160317175043-d3ddb4469d5a/go.mod h1:yo6s7OP7yaDglbqo1J04qKzAhqBH6lvTonzMVmEdcZw=
google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
Expand Down Expand Up @@ -1066,6 +1083,9 @@ google.golang.org/grpc v1.37.1/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQ
google.golang.org/grpc v1.38.0/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
google.golang.org/grpc v1.39.0 h1:Klz8I9kdtkIN6EpHHUOMLCYhTn/2WAe5a0s1hcBkdTI=
google.golang.org/grpc v1.39.0/go.mod h1:PImNr+rS9TWYb2O4/emRugxiyHZ5JyHW5F+RPnDzfrE=
google.golang.org/grpc v1.39.1/go.mod h1:PImNr+rS9TWYb2O4/emRugxiyHZ5JyHW5F+RPnDzfrE=
google.golang.org/grpc v1.40.0 h1:AGJ0Ih4mHjSeibYkFGh1dD9KJ/eOtZ93I6hoHhukQ5Q=
google.golang.org/grpc v1.40.0/go.mod h1:ogyxbiOoUXAkP+4+xa6PZSE9DZgIHtSpzjDTB9KAK34=
google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.1.0/go.mod h1:6Kw0yEErY5E/yWrBtf03jp27GLLJujG4z/JK95pnjjw=
google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
Expand Down
107 changes: 107 additions & 0 deletions examples/mutations/main.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,107 @@
// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
"context"
"database/sql"
"fmt"
"time"

"cloud.google.com/go/spanner"
"github.com/cloudspannerecosystem/go-sql-spanner"
"github.com/cloudspannerecosystem/go-sql-spanner/examples"
)

var createTableStatement = "CREATE TABLE Singers (SingerId INT64, Name STRING(MAX)) PRIMARY KEY (SingerId)"

func mutations(projectId, instanceId, databaseId string) error {
ctx := context.Background()
db, err := sql.Open("spanner", fmt.Sprintf("projects/%s/instances/%s/databases/%s", projectId, instanceId, databaseId))
if err != nil {
return err
}
defer db.Close()

// Get a connection so that we can get access to the Spanner specific connection interface SpannerConn.
con, err := db.Conn(ctx)
if err != nil {
return err
}

// Mutations can be written outside an explicit transaction using SpannerConn#Apply.
var commitTimestamp time.Time
if err := con.Raw(func(driverConn interface{}) error {
spannerConn, ok := driverConn.(spannerdriver.SpannerConn)
if !ok {
return fmt.Errorf("unexpected driver connection %v, expected SpannerConn", driverConn)
}
commitTimestamp, err = spannerConn.Apply(ctx, []*spanner.Mutation{
spanner.Insert("Singers", []string{"SingerId", "Name"}, []interface{}{int64(1), "Richard Moore"}),
spanner.Insert("Singers", []string{"SingerId", "Name"}, []interface{}{int64(2), "Alice Henderson"}),
})
return err
}); err != nil {
return err
}
fmt.Printf("The transaction with two singer mutations was committed at %v\n", commitTimestamp)

// Mutations can also be executed as part of a read/write transaction.
// Note: The transaction is started using the connection that we had obtained. This is necessary in order to
// ensure that the con.Raw call below will use the same connection as the one that just started the transaction.
tx, err := con.BeginTx(ctx, &sql.TxOptions{})
if err != nil {
return err
}

// Get the name of a singer and update it using a mutation.
id := int64(1)
row := tx.QueryRowContext(ctx, "SELECT Name FROM Singers WHERE SingerId=@id", id)
var name string
if err := row.Scan(&name); err != nil {
return err
}
if err := con.Raw(func(driverConn interface{}) error {
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Since there is no txn here, I assume that in con, there is a txn context that is created by the previous call con.BeginTx, is this right?

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Yes, that is correct. Unfortunately go-sql does not support executing something like tx.Raw, only conn.Raw.

spannerConn, ok := driverConn.(spannerdriver.SpannerConn)
if !ok {
return fmt.Errorf("unexpected driver connection %v, expected SpannerConn", driverConn)
}
return spannerConn.BufferWrite([]*spanner.Mutation{
spanner.Update("Singers", []string{"SingerId", "Name"}, []interface{}{id, name + "-Henderson"}),
})
}); err != nil {
return err
}
if err := tx.Commit(); err != nil {
return err
}
fmt.Print("Updated the name of the first singer\n")

// Read back the updated row.
row = db.QueryRowContext(ctx, "SELECT SingerId, Name FROM Singers WHERE SingerId = @id", id)
if err := row.Err(); err != nil {
return err
}
if err := row.Scan(&id, &name); err != nil {
return err
}
fmt.Printf("Updated singer: %v %v\n", id, name)

return nil
}

func main() {
examples.RunSampleOnEmulator(mutations, createTableStatement)
}
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