Use pgconn.PreparedStatementDescription directly

Instead of having similar pgx.PreparedStatement

conn.go

@@ -43,7 +43,7 @@ type ConnConfig struct {
 type Conn struct {
 	pgConn             *pgconn.PgConn
 	config             *ConnConfig // config used when establishing this connection
-	preparedStatements map[string]*PreparedStatement
+	preparedStatements map[string]*pgconn.PreparedStatementDescription
 	logger             Logger
 	logLevel           LogLevel
 
@@ -61,14 +61,6 @@ type Conn struct {
 	eqb              extendedQueryBuilder
 }
 
-// PreparedStatement is a description of a prepared statement
-type PreparedStatement struct {
-	Name              string
-	SQL               string
-	FieldDescriptions []pgproto3.FieldDescription
-	ParameterOIDs     []uint32
-}
-
 // Identifier a PostgreSQL identifier or name. Identifiers can be composed of
 // multiple parts such as ["schema", "table"] or ["table", "column"].
 type Identifier []string
@@ -172,7 +164,7 @@ func connect(ctx context.Context, config *ConnConfig) (c *Conn, err error) {
 		return nil, err
 	}
 
-	c.preparedStatements = make(map[string]*PreparedStatement)
+	c.preparedStatements = make(map[string]*pgconn.PreparedStatementDescription)
 	c.doneChan = make(chan struct{})
 	c.closedChan = make(chan error)
 	c.wbuf = make([]byte, 0, 1024)
@@ -207,10 +199,11 @@ func (c *Conn) Close(ctx context.Context) error {
 // Prepare is idempotent; i.e. it is safe to call Prepare multiple times with the same
 // name and sql arguments. This allows a code path to Prepare and Query/Exec without
 // concern for if the statement has already been prepared.
-func (c *Conn) Prepare(ctx context.Context, name, sql string) (ps *PreparedStatement, err error) {
+func (c *Conn) Prepare(ctx context.Context, name, sql string) (psd *pgconn.PreparedStatementDescription, err error) {
 	if name != "" {
-		if ps, ok := c.preparedStatements[name]; ok && ps.SQL == sql {
+		var ok bool
-			return ps, nil
+		if psd, ok = c.preparedStatements[name]; ok && psd.SQL == sql {
+			return psd, nil
 		}
 	}
 
@@ -222,27 +215,16 @@ func (c *Conn) Prepare(ctx context.Context, name, sql string) (ps *PreparedState
 		}()
 	}
 
-	psd, err := c.pgConn.Prepare(ctx, name, sql, nil)
+	psd, err = c.pgConn.Prepare(ctx, name, sql, nil)
 	if err != nil {
 		return nil, err
 	}
 
-	ps = &PreparedStatement{
-		Name:              psd.Name,
-		SQL:               psd.SQL,
-		ParameterOIDs:     make([]uint32, len(psd.ParamOIDs)),
-		FieldDescriptions: psd.Fields,
-	}
-
-	for i := range ps.ParameterOIDs {
-		ps.ParameterOIDs[i] = uint32(psd.ParamOIDs[i])
-	}
-
 	if name != "" {
-		c.preparedStatements[name] = ps
+		c.preparedStatements[name] = psd
 	}
 
-	return ps, nil
+	return psd, nil
 }
 
 // Deallocate released a prepared statement
@@ -464,7 +446,7 @@ func (c *Conn) execSimpleProtocol(ctx context.Context, sql string, arguments []i
 	return commandTag, err
 }
 
-func (c *Conn) execPrepared(ctx context.Context, ps *PreparedStatement, arguments []interface{}) (commandTag pgconn.CommandTag, err error) {
+func (c *Conn) execPrepared(ctx context.Context, ps *pgconn.PreparedStatementDescription, arguments []interface{}) (commandTag pgconn.CommandTag, err error) {
 	c.eqb.Reset()
 
 	args, err := convertDriverValuers(arguments)
@@ -473,14 +455,14 @@ func (c *Conn) execPrepared(ctx context.Context, ps *PreparedStatement, argument
 	}
 
 	for i := range args {
-		err = c.eqb.AppendParam(c.ConnInfo, ps.ParameterOIDs[i], args[i])
+		err = c.eqb.AppendParam(c.ConnInfo, ps.ParamOIDs[i], args[i])
 		if err != nil {
 			return nil, err
 		}
 	}
 
-	for i := range ps.FieldDescriptions {
+	for i := range ps.Fields {
-		if dt, ok := c.ConnInfo.DataTypeForOID(uint32(ps.FieldDescriptions[i].DataTypeOID)); ok {
+		if dt, ok := c.ConnInfo.DataTypeForOID(uint32(ps.Fields[i].DataTypeOID)); ok {
 			if _, ok := dt.Value.(pgtype.BinaryDecoder); ok {
 				c.eqb.AppendResultFormat(BinaryFormatCode)
 			} else {
@@ -571,27 +553,16 @@ optionLoop:
 
 	ps, ok := c.preparedStatements[sql]
 	if !ok {
-		psd, err := c.pgConn.Prepare(ctx, "", sql, nil)
+		ps, err = c.pgConn.Prepare(ctx, "", sql, nil)
 		if err != nil {
 			rows.fatal(err)
 			return rows, rows.err
 		}
 
-		if len(psd.ParamOIDs) != len(args) {
+		if len(ps.ParamOIDs) != len(args) {
-			rows.fatal(errors.Errorf("expected %d arguments, got %d", len(psd.ParamOIDs), len(args)))
+			rows.fatal(errors.Errorf("expected %d arguments, got %d", len(ps.ParamOIDs), len(args)))
 			return rows, rows.err
 		}
-
-		ps = &PreparedStatement{
-			Name:              psd.Name,
-			SQL:               psd.SQL,
-			ParameterOIDs:     make([]uint32, len(psd.ParamOIDs)),
-			FieldDescriptions: psd.Fields,
-		}
-
-		for i := range ps.ParameterOIDs {
-			ps.ParameterOIDs[i] = uint32(psd.ParamOIDs[i])
-		}
 	}
 	rows.sql = ps.SQL
 
@@ -602,7 +573,7 @@ optionLoop:
 	}
 
 	for i := range args {
-		err = c.eqb.AppendParam(c.ConnInfo, ps.ParameterOIDs[i], args[i])
+		err = c.eqb.AppendParam(c.ConnInfo, ps.ParamOIDs[i], args[i])
 		if err != nil {
 			rows.fatal(err)
 			return rows, rows.err
@@ -610,15 +581,15 @@ optionLoop:
 	}
 
 	if resultFormatsByOID != nil {
-		resultFormats = make([]int16, len(ps.FieldDescriptions))
+		resultFormats = make([]int16, len(ps.Fields))
 		for i := range resultFormats {
-			resultFormats[i] = resultFormatsByOID[uint32(ps.FieldDescriptions[i].DataTypeOID)]
+			resultFormats[i] = resultFormatsByOID[uint32(ps.Fields[i].DataTypeOID)]
 		}
 	}
 
 	if resultFormats == nil {
-		for i := range ps.FieldDescriptions {
+		for i := range ps.Fields {
-			if dt, ok := c.ConnInfo.DataTypeForOID(uint32(ps.FieldDescriptions[i].DataTypeOID)); ok {
+			if dt, ok := c.ConnInfo.DataTypeForOID(uint32(ps.Fields[i].DataTypeOID)); ok {
 				if _, ok := dt.Value.(pgtype.BinaryDecoder); ok {
 					c.eqb.AppendResultFormat(BinaryFormatCode)
 				} else {
@@ -655,7 +626,7 @@ func (c *Conn) SendBatch(ctx context.Context, b *Batch) BatchResults {
 		ps := c.preparedStatements[bi.query]
 
 		if ps != nil {
-			parameterOIDs = ps.ParameterOIDs
+			parameterOIDs = ps.ParamOIDs
 		} else {
 			parameterOIDs = bi.parameterOIDs
 		}
@@ -677,8 +648,8 @@ func (c *Conn) SendBatch(ctx context.Context, b *Batch) BatchResults {
 			resultFormats := bi.resultFormatCodes
 			if resultFormats == nil {
 
-				for i := range ps.FieldDescriptions {
+				for i := range ps.Fields {
-					if dt, ok := c.ConnInfo.DataTypeForOID(uint32(ps.FieldDescriptions[i].DataTypeOID)); ok {
+					if dt, ok := c.ConnInfo.DataTypeForOID(uint32(ps.Fields[i].DataTypeOID)); ok {
 						if _, ok := dt.Value.(pgtype.BinaryDecoder); ok {
 							c.eqb.AppendResultFormat(BinaryFormatCode)
 						} else {

copy_from.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/jackc/pgconn"
 	"github.com/jackc/pgio"
 	errors "golang.org/x/xerrors"
 )
@@ -116,7 +117,7 @@ func (ct *copyFrom) run(ctx context.Context) (int64, error) {
 	return commandTag.RowsAffected(), err
 }
 
-func (ct *copyFrom) buildCopyBuf(buf []byte, ps *PreparedStatement) (bool, []byte, error) {
+func (ct *copyFrom) buildCopyBuf(buf []byte, ps *pgconn.PreparedStatementDescription) (bool, []byte, error) {
 
 	for ct.rowSrc.Next() {
 		values, err := ct.rowSrc.Values()
@@ -129,7 +130,7 @@ func (ct *copyFrom) buildCopyBuf(buf []byte, ps *PreparedStatement) (bool, []byt
 
 		buf = pgio.AppendInt16(buf, int16(len(ct.columnNames)))
 		for i, val := range values {
-			buf, err = encodePreparedStatementArgument(ct.conn.ConnInfo, buf, uint32(ps.FieldDescriptions[i].DataTypeOID), val)
+			buf, err = encodePreparedStatementArgument(ct.conn.ConnInfo, buf, ps.Fields[i].DataTypeOID, val)
 			if err != nil {
 				return false, nil, err
 			}

pgxpool/tx.go

@@ -46,7 +46,7 @@ func (tx *Tx) LargeObjects() pgx.LargeObjects {
 	return tx.t.LargeObjects()
 }
 
-func (tx *Tx) Prepare(ctx context.Context, name, sql string) (*pgx.PreparedStatement, error) {
+func (tx *Tx) Prepare(ctx context.Context, name, sql string) (*pgconn.PreparedStatementDescription, error) {
 	return tx.t.Prepare(ctx, name, sql)
 }
 

stdlib/sql.go

@@ -164,12 +164,12 @@ func (c *Conn) PrepareContext(ctx context.Context, query string) (driver.Stmt, e
 	name := fmt.Sprintf("pgx_%d", c.psCount)
 	c.psCount++
 
-	ps, err := c.conn.Prepare(ctx, name, query)
+	psd, err := c.conn.Prepare(ctx, name, query)
 	if err != nil {
 		return nil, err
 	}
 
-	return &Stmt{ps: ps, conn: c}, nil
+	return &Stmt{psd: psd, conn: c}, nil
 }
 
 func (c *Conn) Close() error {
@@ -265,16 +265,16 @@ func (c *Conn) Ping(ctx context.Context) error {
 }
 
 type Stmt struct {
-	ps   *pgx.PreparedStatement
+	psd  *pgconn.PreparedStatementDescription
 	conn *Conn
 }
 
 func (s *Stmt) Close() error {
-	return s.conn.conn.Deallocate(context.Background(), s.ps.Name)
+	return s.conn.conn.Deallocate(context.Background(), s.psd.Name)
 }
 
 func (s *Stmt) NumInput() int {
-	return len(s.ps.ParameterOIDs)
+	return len(s.psd.ParamOIDs)
 }
 
 func (s *Stmt) Exec(argsV []driver.Value) (driver.Result, error) {
@@ -282,7 +282,7 @@ func (s *Stmt) Exec(argsV []driver.Value) (driver.Result, error) {
 }
 
 func (s *Stmt) ExecContext(ctx context.Context, argsV []driver.NamedValue) (driver.Result, error) {
-	return s.conn.ExecContext(ctx, s.ps.Name, argsV)
+	return s.conn.ExecContext(ctx, s.psd.Name, argsV)
 }
 
 func (s *Stmt) Query(argsV []driver.Value) (driver.Rows, error) {
@@ -290,7 +290,7 @@ func (s *Stmt) Query(argsV []driver.Value) (driver.Rows, error) {
 }
 
 func (s *Stmt) QueryContext(ctx context.Context, argsV []driver.NamedValue) (driver.Rows, error) {
-	return s.conn.QueryContext(ctx, s.ps.Name, argsV)
+	return s.conn.QueryContext(ctx, s.psd.Name, argsV)
 }
 
 type Rows struct {

tx.go

@@ -95,7 +95,7 @@ type Tx interface {
 	SendBatch(ctx context.Context, b *Batch) BatchResults
 	LargeObjects() LargeObjects
 
-	Prepare(ctx context.Context, name, sql string) (*PreparedStatement, error)
+	Prepare(ctx context.Context, name, sql string) (*pgconn.PreparedStatementDescription, error)
 
 	Exec(ctx context.Context, sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error)
 	Query(ctx context.Context, sql string, args ...interface{}) (Rows, error)
@@ -174,7 +174,7 @@ func (tx *dbTx) Exec(ctx context.Context, sql string, arguments ...interface{})
 }
 
 // Prepare delegates to the underlying *Conn
-func (tx *dbTx) Prepare(ctx context.Context, name, sql string) (*PreparedStatement, error) {
+func (tx *dbTx) Prepare(ctx context.Context, name, sql string) (*pgconn.PreparedStatementDescription, error) {
 	if tx.closed {
 		return nil, ErrTxClosed
 	}
@@ -264,7 +264,7 @@ func (sp *dbSavepoint) Exec(ctx context.Context, sql string, arguments ...interf
 }
 
 // Prepare delegates to the underlying Tx
-func (sp *dbSavepoint) Prepare(ctx context.Context, name, sql string) (*PreparedStatement, error) {
+func (sp *dbSavepoint) Prepare(ctx context.Context, name, sql string) (*pgconn.PreparedStatementDescription, error) {
 	if sp.closed {
 		return nil, ErrTxClosed
 	}