MySQL LOAD DATA INFILE: First version

This enables the :copyfrom query annotation for people using
go-sql-driver/mysql that transforms it into a LOAD DATA LOCAL INFILE.

issue sqlc-dev#2179

Author: Jille

internal/codegen/golang/gen.go

@@ -138,8 +138,8 @@ func generate(req *plugin.CodeGenRequest, enums []Enum, structs []Struct, querie
 		SqlcVersion:               req.SqlcVersion,
 	}
 
-	if tctx.UsesCopyFrom && !tctx.SQLDriver.IsPGX() {
-		return nil, errors.New(":copyfrom is only supported by pgx")
+	if tctx.UsesCopyFrom && !tctx.SQLDriver.IsPGX() && golang.SqlDriver != SQLDriverGoSQLDriverMySQL {
+		return nil, errors.New(":copyfrom is only supported by pgx and github.com/go-sql-driver/mysql")
 	}
 
 	if tctx.UsesBatch && !tctx.SQLDriver.IsPGX() {

internal/codegen/golang/imports.go

@@ -414,6 +414,13 @@ func (i *importer) copyfromImports() fileImports {
 	})
 
 	std["context"] = struct{}{}
+	if i.Settings.Go.SqlDriver == SQLDriverGoSQLDriverMySQL {
+		std["io"] = struct{}{}
+		std["fmt"] = struct{}{}
+		std["sync/atomic"] = struct{}{}
+		std["github.com/go-sql-driver/mysql"] = struct{}{}
+		std["github.com/hexon/mysqltsv"] = struct{}{}
+	}
 
 	return sortedImports(std, pkg)
 }

internal/codegen/golang/query.go

@@ -131,7 +131,18 @@ func (v QueryValue) Params() string {
 	return "\n" + strings.Join(out, ",\n")
 }
 
-func (v QueryValue) ColumnNames() string {
+func (v QueryValue) ColumnNames() []string {
+	if v.Struct == nil {
+		return []string{v.DBName}
+	}
+	names := make([]string, len(v.Struct.Fields))
+	for i, f := range v.Struct.Fields {
+		names[i] = f.DBName
+	}
+	return names
+}
+
+func (v QueryValue) ColumnNamesAsGoSlice() string {
 	if v.Struct == nil {
 		return fmt.Sprintf("[]string{%q}", v.DBName)
 	}
@@ -189,6 +200,19 @@ func (v QueryValue) Scan() string {
 	return "\n" + strings.Join(out, ",\n")
 }
 
+func (v QueryValue) Fields() []Field {
+	if v.Struct != nil {
+		return v.Struct.Fields
+	}
+	return []Field{
+		{
+			Name:   v.Name,
+			DBName: v.DBName,
+			Type:   v.Typ,
+		},
+	}
+}
+
 // A struct used to generate methods and fields on the Queries struct
 type Query struct {
 	Cmd          string
@@ -210,7 +234,7 @@ func (q Query) hasRetType() bool {
 	return scanned && !q.Ret.isEmpty()
 }
 
-func (q Query) TableIdentifier() string {
+func (q Query) TableIdentifierAsGoSlice() string {
 	escapedNames := make([]string, 0, 3)
 	for _, p := range []string{q.Table.Catalog, q.Table.Schema, q.Table.Name} {
 		if p != "" {
@@ -219,3 +243,13 @@ func (q Query) TableIdentifier() string {
 	}
 	return "[]string{" + strings.Join(escapedNames, ", ") + "}"
 }
+
+func (q Query) TableIdentifierForMySQL() string {
+	escapedNames := make([]string, 0, 3)
+	for _, p := range []string{q.Table.Catalog, q.Table.Schema, q.Table.Name} {
+		if p != "" {
+			escapedNames = append(escapedNames, fmt.Sprintf("`%s`", p))
+		}
+	}
+	return strings.Join(escapedNames, ".")
+}

internal/codegen/golang/templates/go-sql-driver-mysql/copyfromCopy.tmpl

@@ -0,0 +1,45 @@
+{{define "copyfromCodeGoSqlDriver"}}
+{{range .GoQueries}}
+{{if eq .Cmd ":copyfrom" }}
+var readerHandlerSequenceFor{{.MethodName}} uint32 = 1
+
+func convertRowsFor{{.MethodName}}(w *io.PipeWriter, {{.Arg.SlicePair}}) {
+	e := mysqltsv.NewEncoder(w, {{ len .Arg.Fields }}, nil)
+	for _, row := range {{.Arg.Name}} {
+{{- with $arg := .Arg }}
+{{- range $arg.Fields}}
+{{- if eq .Type "string"}}
+	e.AppendString({{if eq (len $arg.Fields) 1}}row{{else}}row.{{.Name}}{{end}})
+{{- else if eq .Type "[]byte"}}
+	e.AppendBytes({{if eq (len $arg.Fields) 1}}row{{else}}row.{{.Name}}{{end}})
+{{- else}}
+	e.AppendValue({{if eq (len $arg.Fields) 1}}row{{else}}row.{{.Name}}{{end}})
+{{- end}}
+{{- end}}
+{{- end}}
+	}
+	w.CloseWithError(e.Close())
+}
+
+{{range .Comments}}//{{.}}
+{{end -}}
+// {{.MethodName}} uses MySQL's LOAD DATA LOCAL INFILE and is not atomic. Errors and duplicate keys are treated as warnings and insertion will continue, even without an error for some cases.
+// Use this in a transaction and use SHOW WARNINGS to check for any problems and roll back if you want to.
+// This is a MySQL limitation, not sqlc. Check the documentation for more information: https://dev.mysql.com/doc/refman/8.0/en/load-data.html#load-data-error-handling
+func (q *Queries) {{.MethodName}}(ctx context.Context{{if $.EmitMethodsWithDBArgument}}, db DBTX{{end}}, {{.Arg.SlicePair}}) (int64, error) {
+	pr, pw := io.Pipe()
+	defer pr.Close()
+	rh := fmt.Sprintf("{{.MethodName}}_%d", atomic.AddUint32(&readerHandlerSequenceFor{{.MethodName}}, 1))
+	mysql.RegisterReaderHandler(rh, func() io.Reader { return pr })
+	defer mysql.DeregisterReaderHandler(rh)
+	go convertRowsFor{{.MethodName}}(pw, {{.Arg.Name}})
+	result, err := {{if (not $.EmitMethodsWithDBArgument)}}q.{{end}}db.ExecContext(ctx, fmt.Sprintf("LOAD DATA LOCAL INFILE '%s' INTO TABLE {{.TableIdentifierForMySQL}} %s ({{range $index, $name := .Arg.ColumnNames}}{{if gt $index 0}}, {{end}}{{$name}}{{end}})", "Reader::" + rh, mysqltsv.Escaping))
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
+{{end}}
+{{end}}
+{{end}}

internal/codegen/golang/templates/pgx/copyfromCopy.tmpl

@@ -39,10 +39,10 @@ func (r iteratorFor{{.MethodName}}) Err() error {
 {{end -}}
 {{- if $.EmitMethodsWithDBArgument -}}
 func (q *Queries) {{.MethodName}}(ctx context.Context, db DBTX, {{.Arg.SlicePair}}) (int64, error) {
-	return db.CopyFrom(ctx, {{.TableIdentifier}}, {{.Arg.ColumnNames}}, &iteratorFor{{.MethodName}}{rows: {{.Arg.Name}}})
+	return db.CopyFrom(ctx, {{.TableIdentifierAsGoSlice}}, {{.Arg.ColumnNamesAsGoSlice}}, &iteratorFor{{.MethodName}}{rows: {{.Arg.Name}}})
 {{- else -}}
 func (q *Queries) {{.MethodName}}(ctx context.Context, {{.Arg.SlicePair}}) (int64, error) {
-	return q.db.CopyFrom(ctx, {{.TableIdentifier}}, {{.Arg.ColumnNames}}, &iteratorFor{{.MethodName}}{rows: {{.Arg.Name}}})
+	return q.db.CopyFrom(ctx, {{.TableIdentifierAsGoSlice}}, {{.Arg.ColumnNamesAsGoSlice}}, &iteratorFor{{.MethodName}}{rows: {{.Arg.Name}}})
 {{- end}}
 }
 

internal/codegen/golang/templates/template.tmpl

@@ -186,6 +186,8 @@ import (
 {{define "copyfromCode"}}
 {{if .SQLDriver.IsPGX }}
     {{- template "copyfromCodePgx" .}}
+{{else}}
+    {{- template "copyfromCodeGoSqlDriver" .}}
 {{end}}
 {{end}}
 

internal/endtoend/testdata/copyfrom/mysql/go/copyfrom.go

@@ -0,0 +1,7 @@
+CREATE TABLE foo (a text, b integer, c DATETIME, d DATE);
+
+-- name: InsertValues :copyfrom
+INSERT INTO foo (a, b, c, d) VALUES (?, ?, ?, ?);
+
+-- name: InsertSingleValue :copyfrom
+INSERT INTO foo (a) VALUES (?);

internal/endtoend/testdata/copyfrom/mysql/go/db.go

@@ -0,0 +1,14 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "sql_package": "database/sql",
+      "sql_driver": "github.com/go-sql-driver/mysql",
+      "engine": "mysql",
+      "name": "querytest",
+      "schema": "query.sql",
+      "queries": "query.sql"
+    }
+  ]
+}

internal/endtoend/testdata/copyfrom/mysql/go/models.go

@@ -3,8 +3,10 @@ module github.com/kyleconroy/sqlc/endtoend
 go 1.18
 
 require (
+	github.com/go-sql-driver/mysql v1.7.0
 	github.com/gofrs/uuid v4.0.0+incompatible
 	github.com/google/uuid v1.3.0
+	github.com/hexon/mysqltsv v0.1.0
 	github.com/jackc/pgconn v1.5.1-0.20200601181101-fa742c524853
 	github.com/jackc/pgtype v1.6.2
 	github.com/jackc/pgx/v4 v4.6.1-0.20200606145419-4e5062306904

internal/endtoend/testdata/copyfrom/mysql/go/query.sql.go

@@ -9,13 +9,17 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/friendsofgo/errors v0.9.2 h1:X6NYxef4efCBdwI7BgS820zFaN7Cphrmb+Pljdzjtgk=
 github.com/friendsofgo/errors v0.9.2/go.mod h1:yCvFW5AkDIL9qn7suHVLiI/gH228n7PC4Pn44IGoTOI=
+github.com/go-sql-driver/mysql v1.7.0 h1:ueSltNNllEqE3qcWBTD0iQd3IpL/6U+mJxLkazJ7YPc=
+github.com/go-sql-driver/mysql v1.7.0/go.mod h1:OXbVy3sEdcQ2Doequ6Z5BW6fXNQTmx+9S1MCJN5yJMI=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/gofrs/uuid v3.2.0+incompatible/go.mod h1:b2aQJv3Z4Fp6yNu3cdSllBxTCLRxnplIgP/c0N/04lM=
 github.com/gofrs/uuid v4.0.0+incompatible h1:1SD/1F5pU8p29ybwgQSwpQk+mwdRrXCYuPhW6m+TnJw=
 github.com/gofrs/uuid v4.0.0+incompatible/go.mod h1:b2aQJv3Z4Fp6yNu3cdSllBxTCLRxnplIgP/c0N/04lM=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
 github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/hexon/mysqltsv v0.1.0 h1:48wYQlsPH8ZEkKAVCdsOYzMYAlEoevw8ZWD8rqYPdlg=
+github.com/hexon/mysqltsv v0.1.0/go.mod h1:p3vPBkpxebjHWF1bWKYNcXx5pFu+yAG89QZQEKSvVrY=
 github.com/jackc/chunkreader v1.0.0/go.mod h1:RT6O25fNZIuasFJRyZ4R/Y2BbhasbmZXF9QQ7T3kePo=
 github.com/jackc/chunkreader/v2 v2.0.0/go.mod h1:odVSm741yZoC3dpHEUXIqA9tQRhFrgOHwnPIn9lDKlk=
 github.com/jackc/chunkreader/v2 v2.0.1 h1:i+RDz65UE+mmpjTfyz0MoVTnzeYxroil2G82ki7MGG8=