chore: use a callback to supply tx opts

README.md

@@ -103,10 +103,10 @@ tx.QueryContext(ctx, "SELECT SingerId, Name FROM Singers WHERE SingerId = ?", 12
 
 ## Transactions
 
-- Read-write transactions always uses the strongest isolation level and ignore the user-specified level.
+- Read-write transactions support isolation levels `Serializable`, `Snapshot` and `RepeatableRead`.
 - Read-only transactions do strong-reads by default. Read-only transactions must be ended by calling
   either Commit or Rollback. Calling either of these methods will end the current read-only
-  transaction and return the session that is used to the session pool.
+  transaction.
 
 ```go
 tx, err := db.BeginTx(ctx, &sql.TxOptions{}) // Read-write transaction.
@@ -226,6 +226,11 @@ $ gcloud beta emulators spanner start
 $ export SPANNER_EMULATOR_HOST=localhost:9010
 ```
 
+### Automatically Create Instance and Database on the Emulator
+You can also add the `autoConfigEmulator=true` option to the connection string. This will instruct the driver
+to connect to the Spanner emulator, and to automatically create the Spanner instance and database on the
+emulator. See [examples/emulator](examples/emulator) for a working example.
+
 ## Spanner PostgreSQL Interface
 
 This driver works with both Spanner GoogleSQL and PostgreSQL dialects.

benchmarks/go.mod

@@ -1,24 +1,24 @@
 module github.com/googleapis/go-sql-spanner/benchmarks
 
-go 1.24
+go 1.24.0
 
 toolchain go1.25.0
 
 replace github.com/googleapis/go-sql-spanner => ../
 
 require (
 	cloud.google.com/go v0.121.6
-	cloud.google.com/go/spanner v1.84.1
+	cloud.google.com/go/spanner v1.85.0
 	github.com/google/uuid v1.6.0
-	github.com/googleapis/go-sql-spanner v1.16.3
-	google.golang.org/api v0.247.0
-	google.golang.org/grpc v1.74.2
-	google.golang.org/protobuf v1.36.7
+	github.com/googleapis/go-sql-spanner v1.17.0
+	google.golang.org/api v0.248.0
+	google.golang.org/grpc v1.75.0
+	google.golang.org/protobuf v1.36.8
 )
 
 require (
 	cel.dev/expr v0.24.0 // indirect
-	cloud.google.com/go/auth v0.16.4 // indirect
+	cloud.google.com/go/auth v0.16.5 // indirect
 	cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
 	cloud.google.com/go/compute/metadata v0.8.0 // indirect
 	cloud.google.com/go/iam v1.5.2 // indirect
@@ -60,6 +60,6 @@ require (
 	golang.org/x/text v0.28.0 // indirect
 	golang.org/x/time v0.12.0 // indirect
 	google.golang.org/genproto v0.0.0-20250804133106-a7a43d27e69b // indirect
-	google.golang.org/genproto/googleapis/api v0.0.0-20250804133106-a7a43d27e69b // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20250811230008-5f3141c8851a // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20250818200422-3122310a409c // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250826171959-ef028d996bc1 // indirect
 )

benchmarks/go.sum

@@ -101,8 +101,8 @@ cloud.google.com/go/assuredworkloads v1.7.0/go.mod h1:z/736/oNmtGAyU47reJgGN+KVo
 cloud.google.com/go/assuredworkloads v1.8.0/go.mod h1:AsX2cqyNCOvEQC8RMPnoc0yEarXQk6WEKkxYfL6kGIo=
 cloud.google.com/go/assuredworkloads v1.9.0/go.mod h1:kFuI1P78bplYtT77Tb1hi0FMxM0vVpRC7VVoJC3ZoT0=
 cloud.google.com/go/assuredworkloads v1.10.0/go.mod h1:kwdUQuXcedVdsIaKgKTp9t0UJkE5+PAVNhdQm4ZVq2E=
-cloud.google.com/go/auth v0.16.4 h1:fXOAIQmkApVvcIn7Pc2+5J8QTMVbUGLscnSVNl11su8=
-cloud.google.com/go/auth v0.16.4/go.mod h1:j10ncYwjX/g3cdX7GpEzsdM+d+ZNsXAbb6qXA7p1Y5M=
+cloud.google.com/go/auth v0.16.5 h1:mFWNQ2FEVWAliEQWpAdH80omXFokmrnbDhUS9cBywsI=
+cloud.google.com/go/auth v0.16.5/go.mod h1:utzRfHMP+Vv0mpOkTRQoWD2q3BatTOoWbA7gCc2dUhQ=
 cloud.google.com/go/auth/oauth2adapt v0.2.8 h1:keo8NaayQZ6wimpNSmW5OPc283g65QNIiLpZnkHRbnc=
 cloud.google.com/go/auth/oauth2adapt v0.2.8/go.mod h1:XQ9y31RkqZCcwJWNSx2Xvric3RrU88hAYYbjDWYDL+c=
 cloud.google.com/go/automl v1.5.0/go.mod h1:34EjfoFGMZ5sgJ9EoLsRtdPSNZLcfflJR39VbVNS2M0=
@@ -526,8 +526,8 @@ cloud.google.com/go/shell v1.6.0/go.mod h1:oHO8QACS90luWgxP3N9iZVuEiSF84zNyLytb+
 cloud.google.com/go/spanner v1.41.0/go.mod h1:MLYDBJR/dY4Wt7ZaMIQ7rXOTLjYrmxLE/5ve9vFfWos=
 cloud.google.com/go/spanner v1.44.0/go.mod h1:G8XIgYdOK+Fbcpbs7p2fiprDw4CaZX63whnSMLVBxjk=
 cloud.google.com/go/spanner v1.45.0/go.mod h1:FIws5LowYz8YAE1J8fOS7DJup8ff7xJeetWEo5REA2M=
-cloud.google.com/go/spanner v1.84.1 h1:ShH4Y3YeDtmHa55dFiSS3YtQ0dmCuP0okfAoHp/d68w=
-cloud.google.com/go/spanner v1.84.1/go.mod h1:3GMEIjOcXINJSvb42H3M6TdlGCDzaCFpiiNQpjHPlCM=
+cloud.google.com/go/spanner v1.85.0 h1:VVO3yW+0+Yx9tg4SQaZvJHGAnU6qCnGXQ3NX4E3+src=
+cloud.google.com/go/spanner v1.85.0/go.mod h1:9zhmtOEoYV06nE4Orbin0dc/ugHzZW9yXuvaM61rpxs=
 cloud.google.com/go/speech v1.6.0/go.mod h1:79tcr4FHCimOp56lwC01xnt/WPJZc4v3gzyT7FoBkCM=
 cloud.google.com/go/speech v1.7.0/go.mod h1:KptqL+BAQIhMsj1kOP2la5DSEEerPDuOP/2mmkhHhZQ=
 cloud.google.com/go/speech v1.8.0/go.mod h1:9bYIl1/tjsAnMgKGHKmBZzXKEkGgtU+MpdDPTE9f7y0=
@@ -1308,6 +1308,8 @@ gonum.org/v1/gonum v0.0.0-20180816165407-929014505bf4/go.mod h1:Y+Yx5eoAFn32cQvJ
 gonum.org/v1/gonum v0.8.2/go.mod h1:oe/vMfY3deqTw+1EZJhuvEW2iwGF1bW9wwu7XCu0+v0=
 gonum.org/v1/gonum v0.9.3/go.mod h1:TZumC3NeyVQskjXqmyWt4S3bINhy7B4eYwW69EbyX+0=
 gonum.org/v1/gonum v0.11.0/go.mod h1:fSG4YDCxxUZQJ7rKsQrj0gMOg00Il0Z96/qMA4bVQhA=
+gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
+gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
 gonum.org/v1/netlib v0.0.0-20190313105609-8cb42192e0e0/go.mod h1:wa6Ws7BG/ESfp6dHfk7C6KdzKA7wR7u/rKwOGE66zvw=
 gonum.org/v1/plot v0.0.0-20190515093506-e2840ee46a6b/go.mod h1:Wt8AAjI+ypCyYX3nZBvf6cAIx93T+c/OS2HFAYskSZc=
 gonum.org/v1/plot v0.9.0/go.mod h1:3Pcqqmp6RHvJI72kgb8fThyUnav364FOsdDo2aGW5lY=
@@ -1369,8 +1371,8 @@ google.golang.org/api v0.108.0/go.mod h1:2Ts0XTHNVWxypznxWOYUeI4g3WdP9Pk2Qk58+a/
 google.golang.org/api v0.110.0/go.mod h1:7FC4Vvx1Mooxh8C5HWjzZHcavuS2f6pmJpZx60ca7iI=
 google.golang.org/api v0.111.0/go.mod h1:qtFHvU9mhgTJegR31csQ+rwxyUTHOKFqCKWp1J0fdw0=
 google.golang.org/api v0.114.0/go.mod h1:ifYI2ZsFK6/uGddGfAD5BMxlnkBqCmqHSDUVi45N5Yg=
-google.golang.org/api v0.247.0 h1:tSd/e0QrUlLsrwMKmkbQhYVa109qIintOls2Wh6bngc=
-google.golang.org/api v0.247.0/go.mod h1:r1qZOPmxXffXg6xS5uhx16Fa/UFY8QU/K4bfKrnvovM=
+google.golang.org/api v0.248.0 h1:hUotakSkcwGdYUqzCRc5yGYsg4wXxpkKlW5ryVqvC1Y=
+google.golang.org/api v0.248.0/go.mod h1:yAFUAF56Li7IuIQbTFoLwXTCI6XCFKueOlS7S9e4F9k=
 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=
@@ -1512,10 +1514,10 @@ google.golang.org/genproto v0.0.0-20230331144136-dcfb400f0633/go.mod h1:UUQDJDOl
 google.golang.org/genproto v0.0.0-20230410155749-daa745c078e1/go.mod h1:nKE/iIaLqn2bQwXBg8f1g2Ylh6r5MN5CmZvuzZCgsCU=
 google.golang.org/genproto v0.0.0-20250804133106-a7a43d27e69b h1:eZTgydvqZO44zyTZAvMaSyAxccZZdraiSAGvqOczVvk=
 google.golang.org/genproto v0.0.0-20250804133106-a7a43d27e69b/go.mod h1:suyz2QBHQKlGIF92HEEsCfO1SwxXdk7PFLz+Zd9Uah4=
-google.golang.org/genproto/googleapis/api v0.0.0-20250804133106-a7a43d27e69b h1:ULiyYQ0FdsJhwwZUwbaXpZF5yUE3h+RA+gxvBu37ucc=
-google.golang.org/genproto/googleapis/api v0.0.0-20250804133106-a7a43d27e69b/go.mod h1:oDOGiMSXHL4sDTJvFvIB9nRQCGdLP1o/iVaqQK8zB+M=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20250811230008-5f3141c8851a h1:tPE/Kp+x9dMSwUm/uM0JKK0IfdiJkwAbSMSeZBXXJXc=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20250811230008-5f3141c8851a/go.mod h1:gw1tLEfykwDz2ET4a12jcXt4couGAm7IwsVaTy0Sflo=
+google.golang.org/genproto/googleapis/api v0.0.0-20250818200422-3122310a409c h1:AtEkQdl5b6zsybXcbz00j1LwNodDuH6hVifIaNqk7NQ=
+google.golang.org/genproto/googleapis/api v0.0.0-20250818200422-3122310a409c/go.mod h1:ea2MjsO70ssTfCjiwHgI0ZFqcw45Ksuk2ckf9G468GA=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20250826171959-ef028d996bc1 h1:pmJpJEvT846VzausCQ5d7KreSROcDqmO388w5YbnltA=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20250826171959-ef028d996bc1/go.mod h1:GmFNa4BdJZ2a8G+wCe9Bg3wwThLrJun751XstdJt5Og=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
 google.golang.org/grpc v1.21.1/go.mod h1:oYelfM1adQP15Ek0mdvEgi9Df8B9CZIaU1084ijfRaM=
@@ -1557,8 +1559,8 @@ google.golang.org/grpc v1.52.3/go.mod h1:pu6fVzoFb+NBYNAvQL08ic+lvB2IojljRYuun5v
 google.golang.org/grpc v1.53.0/go.mod h1:OnIrk0ipVdj4N5d9IUoFUx72/VlD7+jUsHwZgwSMQpw=
 google.golang.org/grpc v1.54.0/go.mod h1:PUSEXI6iWghWaB6lXM4knEgpJNu2qUcKfDtNci3EC2g=
 google.golang.org/grpc v1.56.3/go.mod h1:I9bI3vqKfayGqPUAwGdOSu7kt6oIJLixfffKrpXqQ9s=
-google.golang.org/grpc v1.74.2 h1:WoosgB65DlWVC9FqI82dGsZhWFNBSLjQ84bjROOpMu4=
-google.golang.org/grpc v1.74.2/go.mod h1:CtQ+BGjaAIXHs/5YS3i473GqwBBa1zGQNevxdeBEXrM=
+google.golang.org/grpc v1.75.0 h1:+TW+dqTd2Biwe6KKfhE5JpiYIBWq865PhKGSXiivqt4=
+google.golang.org/grpc v1.75.0/go.mod h1:JtPAzKiq4v1xcAB2hydNlWI2RnF85XXcV0mhKXr2ecQ=
 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=
@@ -1577,8 +1579,8 @@ google.golang.org/protobuf v1.28.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqw
 google.golang.org/protobuf v1.28.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 google.golang.org/protobuf v1.29.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
-google.golang.org/protobuf v1.36.7 h1:IgrO7UwFQGJdRNXH/sQux4R1Dj1WAKcLElzeeRaXV2A=
-google.golang.org/protobuf v1.36.7/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
+google.golang.org/protobuf v1.36.8 h1:xHScyCOEuuwZEc6UtSOvPbAT4zRh0xcNRYekJwfqyMc=
+google.golang.org/protobuf v1.36.8/go.mod h1:fuxRtAxBytpl4zzqUh6/eyUujkJdNiuEkXntxiD/uRU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

conn.go

@@ -926,7 +926,10 @@ func (c *conn) execContext(ctx context.Context, query string, execOptions ExecOp
 func (c *conn) options(reset bool) ExecOptions {
 	if reset {
 		defer func() {
-			c.execOptions.TransactionOptions.TransactionTag = ""
+			// Only reset the transaction tag if there is no active transaction on the connection.
+			if !c.inTransaction() {
+				c.execOptions.TransactionOptions.TransactionTag = ""
+			}
 			c.execOptions.QueryOptions.RequestTag = ""
 		}()
 	}
@@ -958,7 +961,7 @@ func (c *conn) withTempTransactionOptions(options *ReadWriteTransactionOptions)
 	c.tempTransactionOptions = options
 }
 
-func (c *conn) getTransactionOptions() ReadWriteTransactionOptions {
+func (c *conn) getTransactionOptions(execOptions ExecOptions) ReadWriteTransactionOptions {
 	if c.tempTransactionOptions != nil {
 		defer func() { c.tempTransactionOptions = nil }()
 		opts := *c.tempTransactionOptions
@@ -971,7 +974,7 @@ func (c *conn) getTransactionOptions() ReadWriteTransactionOptions {
 		c.execOptions.TransactionOptions.TransactionTag = ""
 	}()
 	txOpts := ReadWriteTransactionOptions{
-		TransactionOptions:     c.execOptions.TransactionOptions,
+		TransactionOptions:     execOptions.TransactionOptions,
 		DisableInternalRetries: !c.RetryAbortsInternally(),
 	}
 	// Only use the default isolation level from the connection if the ExecOptions
@@ -1019,7 +1022,7 @@ func (c *conn) Begin() (driver.Tx, error) {
 	return c.BeginTx(context.Background(), driver.TxOptions{})
 }
 
-func (c *conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+func (c *conn) BeginTx(ctx context.Context, driverOpts driver.TxOptions) (driver.Tx, error) {
 	if c.resetForRetry {
 		c.resetForRetry = false
 		return c.tx, nil
@@ -1033,26 +1036,27 @@ func (c *conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, e
 
 	readOnlyTxOpts := c.getReadOnlyTransactionOptions()
 	batchReadOnlyTxOpts := c.getBatchReadOnlyTransactionOptions()
-	readWriteTransactionOptions := c.getTransactionOptions()
+	execOptions := c.execOptions
 	if c.inTransaction() {
 		return nil, spanner.ToSpannerError(status.Errorf(codes.FailedPrecondition, "already in a transaction"))
 	}
 	if c.inBatch() {
 		return nil, status.Error(codes.FailedPrecondition, "This connection has an active batch. Run or abort the batch before starting a new transaction.")
 	}
 
+	isolationLevelFromTxOpts := spannerpb.TransactionOptions_ISOLATION_LEVEL_UNSPECIFIED
 	// Determine whether internal retries have been disabled using a special
 	// value for the transaction isolation level.
 	disableRetryAborts := false
 	batchReadOnly := false
-	sil := opts.Isolation >> 8
-	opts.Isolation = opts.Isolation - sil<<8
-	if opts.Isolation != driver.IsolationLevel(sql.LevelDefault) {
-		level, err := toProtoIsolationLevel(sql.IsolationLevel(opts.Isolation))
+	sil := driverOpts.Isolation >> 8
+	driverOpts.Isolation = driverOpts.Isolation - sil<<8
+	if driverOpts.Isolation != driver.IsolationLevel(sql.LevelDefault) {
+		level, err := toProtoIsolationLevel(sql.IsolationLevel(driverOpts.Isolation))
 		if err != nil {
 			return nil, err
 		}
-		readWriteTransactionOptions.TransactionOptions.IsolationLevel = level
+		isolationLevelFromTxOpts = level
 	}
 	if sil > 0 {
 		switch spannerIsolationLevel(sil) {
@@ -1064,11 +1068,11 @@ func (c *conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, e
 			// ignore
 		}
 	}
-	if batchReadOnly && !opts.ReadOnly {
+	if batchReadOnly && !driverOpts.ReadOnly {
 		return nil, status.Error(codes.InvalidArgument, "levelBatchReadOnly can only be used for read-only transactions")
 	}
 
-	if opts.ReadOnly {
+	if driverOpts.ReadOnly {
 		var logger *slog.Logger
 		var ro *spanner.ReadOnlyTransaction
 		var bo *spanner.BatchReadOnlyTransaction
@@ -1106,7 +1110,23 @@ func (c *conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, e
 		return c.tx, nil
 	}
 
-	tx, err := spanner.NewReadWriteStmtBasedTransactionWithOptions(ctx, c.client, readWriteTransactionOptions.TransactionOptions)
+	opts := spanner.TransactionOptions{}
+	if c.tempTransactionOptions != nil {
+		opts = c.tempTransactionOptions.TransactionOptions
+	}
+	opts.BeginTransactionOption = c.convertDefaultBeginTransactionOption(opts.BeginTransactionOption)
+	tempCloseFunc := func() {}
+	if c.tempTransactionOptions != nil && c.tempTransactionOptions.close != nil {
+		tempCloseFunc = c.tempTransactionOptions.close
+	}
+	disableInternalRetries := !c.RetryAbortsInternally()
+	if c.tempTransactionOptions != nil {
+		disableInternalRetries = c.tempTransactionOptions.DisableInternalRetries
+	}
+
+	tx, err := spanner.NewReadWriteStmtBasedTransactionWithCallbackForOptions(ctx, c.client, opts, func() spanner.TransactionOptions {
+		return c.effectiveTransactionOptions(isolationLevelFromTxOpts, execOptions)
+	})
 	if err != nil {
 		return nil, err
 	}
@@ -1117,9 +1137,7 @@ func (c *conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, e
 		logger: logger,
 		rwTx:   tx,
 		close: func(result txResult, commitResponse *spanner.CommitResponse, commitErr error) {
-			if readWriteTransactionOptions.close != nil {
-				readWriteTransactionOptions.close()
-			}
+			tempCloseFunc()
 			c.prevTx = c.tx
 			c.tx = nil
 			if commitErr == nil {
@@ -1134,12 +1152,21 @@ func (c *conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, e
 			}
 		},
 		// Disable internal retries if any of these options have been set.
-		retryAborts: !readWriteTransactionOptions.DisableInternalRetries && !disableRetryAborts,
+		retryAborts: !disableInternalRetries && !disableRetryAborts,
 	}
 	c.commitResponse = nil
 	return c.tx, nil
 }
 
+func (c *conn) effectiveTransactionOptions(isolationLevelFromTxOpts spannerpb.TransactionOptions_IsolationLevel, execOptions ExecOptions) spanner.TransactionOptions {
+	readWriteTransactionOptions := c.getTransactionOptions(execOptions)
+	res := readWriteTransactionOptions.TransactionOptions
+	if isolationLevelFromTxOpts != spannerpb.TransactionOptions_ISOLATION_LEVEL_UNSPECIFIED {
+		res.IsolationLevel = isolationLevelFromTxOpts
+	}
+	return res
+}
+
 func (c *conn) convertDefaultBeginTransactionOption(opt spanner.BeginTransactionOption) spanner.BeginTransactionOption {
 	if opt == spanner.DefaultBeginTransaction {
 		if propertyBeginTransactionOption.GetValueOrDefault(c.state) == spanner.DefaultBeginTransaction {

driver.go

@@ -85,8 +85,8 @@ var noopLogger = slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{L
 //     The default is false
 //     - enableEndToEndTracing: Boolean that indicates if end-to-end tracing is enabled
 //     The default is false
-//     - minSessions: The minimum number of sessions in the backing session pool. The default is 100.
-//     - maxSessions: The maximum number of sessions in the backing session pool. The default is 400.
+//     - minSessions (DEPRECATED): The minimum number of sessions in the backing session pool. The default is 100. This option is deprecated, as the driver by default uses a single multiplexed session for all operations.
+//     - maxSessions (DEPRECATED): The maximum number of sessions in the backing session pool. The default is 400. This option is deprecated, as the driver by default uses a single multiplexed session for all operations.
 //     - numChannels: The number of gRPC channels to use to communicate with Cloud Spanner. The default is 4.
 //     - optimizerVersion: Sets the default query optimizer version to use for this connection.
 //     - optimizerStatisticsPackage: Sets the default query optimizer statistic package to use for this connection.

driver_test.go

@@ -284,7 +284,7 @@ func TestExtractDnsParts(t *testing.T) {
 				if err != nil {
 					t.Fatalf("failed to get connector for %q: %v", tc.input, err)
 				}
-				if diff := cmp.Diff(conn.spannerClientConfig, tc.wantSpannerConfig, cmpopts.IgnoreUnexported(spanner.ClientConfig{}, spanner.SessionPoolConfig{}, spanner.InactiveTransactionRemovalOptions{}, spannerpb.ExecuteSqlRequest_QueryOptions{})); diff != "" {
+				if diff := cmp.Diff(conn.spannerClientConfig, tc.wantSpannerConfig, cmpopts.IgnoreUnexported(spanner.ClientConfig{}, spanner.SessionPoolConfig{}, spanner.InactiveTransactionRemovalOptions{}, spannerpb.ExecuteSqlRequest_QueryOptions{}, spanner.TransactionOptions{})); diff != "" {
 					t.Errorf("connector Spanner client config mismatch for %q\n%v", tc.input, diff)
 				}
 				actualConfig := conn.connectorConfig