Composite key support in destination

README.md

@@ -215,11 +215,6 @@ pipelines:
           # Type: string
           # Required: yes
           url: ""
-          # Key represents the column name for the key used to identify and
-          # update existing rows.
-          # Type: string
-          # Required: no
-          key: ""
           # Table is used as the target table into which records are inserted.
           # Type: string
           # Required: no

connector.yaml

@@ -230,11 +230,6 @@ specification:
         validations:
           - type: required
             value: ""
-      - name: key
-        description: Key represents the column name for the key used to identify and update existing rows.
-        type: string
-        default: ""
-        validations: []
       - name: table
         description: Table is used as the target table into which records are inserted.
         type: string

destination.go

@@ -18,7 +18,9 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"maps"
 	"math/big"
+	"slices"
 	"strings"
 
 	sq "github.com/Masterminds/squirrel"
@@ -74,6 +76,10 @@ func (d *Destination) Write(ctx context.Context, recs []opencdc.Record) (int, er
 	b := &pgx.Batch{}
 	for _, rec := range recs {
 		var err error
+		rec, err = d.cleanRecord(rec)
+		if err != nil {
+			return 0, fmt.Errorf("failed to clean record: %w", err)
+		}
 		switch rec.Operation {
 		case opencdc.OperationCreate:
 			err = d.handleInsert(ctx, rec, b)
@@ -117,9 +123,6 @@ func (d *Destination) Teardown(ctx context.Context) error {
 // exists and no key column name is configured, it will plainly insert the data.
 // Otherwise it upserts the record.
 func (d *Destination) handleInsert(ctx context.Context, r opencdc.Record, b *pgx.Batch) error {
-	if !d.hasKey(r) || d.config.Key == "" {
-		return d.insert(ctx, r, b)
-	}
 	return d.upsert(ctx, r, b)
 }
 
@@ -143,179 +146,114 @@ func (d *Destination) handleDelete(ctx context.Context, r opencdc.Record, b *pgx
 }
 
 func (d *Destination) upsert(ctx context.Context, r opencdc.Record, b *pgx.Batch) error {
-	payload, err := d.getPayload(r)
-	if err != nil {
-		return fmt.Errorf("failed to get payload: %w", err)
-	}
-
-	key, err := d.getKey(r)
-	if err != nil {
-		return fmt.Errorf("failed to get key: %w", err)
-	}
-
-	keyColumnName := d.getKeyColumnName(key, d.config.Key)
-
+	payload := r.Payload.After.(opencdc.StructuredData)
+	key := r.Key.(opencdc.StructuredData)
 	tableName, err := d.getTableName(r)
 	if err != nil {
-		return fmt.Errorf("failed to get table name for write: %w", err)
+		return fmt.Errorf("failed to get table name for upsert: %w", err)
 	}
 
-	query, args, err := d.formatUpsertQuery(ctx, key, payload, keyColumnName, tableName)
+	query, args, err := d.formatUpsertQuery(ctx, key, payload, tableName)
 	if err != nil {
 		return fmt.Errorf("error formatting query: %w", err)
 	}
 	sdk.Logger(ctx).Trace().
-		Str("table_name", tableName).
-		Any("key", map[string]interface{}{keyColumnName: key[keyColumnName]}).
+		Str("table", tableName).
+		Str("query", query).
+		Any("key", key).
 		Msg("upserting record")
 
 	b.Queue(query, args...)
 	return nil
 }
 
 func (d *Destination) remove(ctx context.Context, r opencdc.Record, b *pgx.Batch) error {
-	key, err := d.getKey(r)
-	if err != nil {
-		return err
-	}
-	keyColumnName := d.getKeyColumnName(key, d.config.Key)
+	key := r.Key.(opencdc.StructuredData)
 	tableName, err := d.getTableName(r)
 	if err != nil {
-		return fmt.Errorf("failed to get table name for write: %w", err)
+		return fmt.Errorf("failed to get table name for delete: %w", err)
+	}
+
+	where := make(sq.Eq)
+	for col, val := range key {
+		where[internal.WrapSQLIdent(col)] = val
 	}
 
-	sdk.Logger(ctx).Trace().
-		Str("table_name", tableName).
-		Any("key", map[string]interface{}{keyColumnName: key[keyColumnName]}).
-		Msg("deleting record")
 	query, args, err := d.stmtBuilder.
 		Delete(internal.WrapSQLIdent(tableName)).
-		Where(sq.Eq{internal.WrapSQLIdent(keyColumnName): key[keyColumnName]}).
+		Where(where).
 		ToSql()
 	if err != nil {
 		return fmt.Errorf("error formatting delete query: %w", err)
 	}
 
-	b.Queue(query, args...)
-	return nil
-}
-
-// insert is an append-only operation that doesn't care about keys, but
-// can error on constraints violations so should only be used when no table
-// key or unique constraints are otherwise present.
-func (d *Destination) insert(ctx context.Context, r opencdc.Record, b *pgx.Batch) error {
-	tableName, err := d.getTableName(r)
-	if err != nil {
-		return err
-	}
-
-	key, err := d.getKey(r)
-	if err != nil {
-		return err
-	}
-
-	payload, err := d.getPayload(r)
-	if err != nil {
-		return err
-	}
-
-	colArgs, valArgs, err := d.formatColumnsAndValues(ctx, tableName, key, payload)
-	if err != nil {
-		return fmt.Errorf("error formatting columns and values: %w", err)
-	}
-
 	sdk.Logger(ctx).Trace().
-		Str("table_name", tableName).
-		Msg("inserting record")
-	query, args, err := d.stmtBuilder.
-		Insert(internal.WrapSQLIdent(tableName)).
-		Columns(colArgs...).
-		Values(valArgs...).
-		ToSql()
-	if err != nil {
-		return fmt.Errorf("error formatting insert query: %w", err)
-	}
+		Str("table", tableName).
+		Str("query", query).
+		Any("key", key).
+		Msg("deleting record")
 
 	b.Queue(query, args...)
 	return nil
 }
 
-func (d *Destination) getPayload(r opencdc.Record) (opencdc.StructuredData, error) {
-	if r.Payload.After == nil {
-		return opencdc.StructuredData{}, nil
-	}
-	return d.structuredDataFormatter(r.Payload.After)
-}
-
-func (d *Destination) getKey(r opencdc.Record) (opencdc.StructuredData, error) {
-	if r.Key == nil {
-		return opencdc.StructuredData{}, nil
-	}
-	return d.structuredDataFormatter(r.Key)
-}
-
-func (d *Destination) structuredDataFormatter(data opencdc.Data) (opencdc.StructuredData, error) {
-	if data == nil {
-		return opencdc.StructuredData{}, nil
-	}
-	if sdata, ok := data.(opencdc.StructuredData); ok {
-		return sdata, nil
-	}
-	raw := data.Bytes()
-	if len(raw) == 0 {
-		return opencdc.StructuredData{}, nil
-	}
-
-	m := make(map[string]interface{})
-	err := json.Unmarshal(raw, &m)
-	if err != nil {
-		return nil, err
-	}
-	return m, nil
-}
-
 // formatUpsertQuery manually formats the UPSERT and ON CONFLICT query statements.
 // The `ON CONFLICT` portion of this query needs to specify the constraint
 // name.
 // * In our case, we can only rely on the record.Key's parsed key value.
 // * If other schema constraints prevent a write, this won't upsert on
 // that conflict.
-func (d *Destination) formatUpsertQuery(ctx context.Context, key opencdc.StructuredData, payload opencdc.StructuredData, keyColumnName string, tableName string) (string, []interface{}, error) {
-	upsertQuery := fmt.Sprintf("ON CONFLICT (%s) DO UPDATE SET", internal.WrapSQLIdent(keyColumnName))
-	for column := range payload {
-		// tuples form a comma separated list, so they need a comma at the end.
-		// `EXCLUDED` references the new record's values. This will overwrite
-		// every column's value except for the key column.
-		wrappedCol := internal.WrapSQLIdent(column)
-		tuple := fmt.Sprintf("%s=EXCLUDED.%s,", wrappedCol, wrappedCol)
-		// TODO: Consider removing this space.
-		upsertQuery += " "
-		// add the tuple to the query string
-		upsertQuery += tuple
-	}
-
-	// remove the last comma from the list of tuples
-	upsertQuery = strings.TrimSuffix(upsertQuery, ",")
-
-	// we have to manually append a semicolon to the upsert sql;
-	upsertQuery += ";"
-
-	colArgs, valArgs, err := d.formatColumnsAndValues(ctx, tableName, key, payload)
+func (d *Destination) formatUpsertQuery(
+	ctx context.Context,
+	key, payload opencdc.StructuredData,
+	tableName string,
+) (string, []interface{}, error) {
+	colArgs, valArgs, err := d.formatColumnsAndValues(ctx, key, payload, tableName)
 	if err != nil {
 		return "", nil, fmt.Errorf("error formatting columns and values: %w", err)
 	}
 
-	return d.stmtBuilder.
+	stmt := d.stmtBuilder.
 		Insert(internal.WrapSQLIdent(tableName)).
 		Columns(colArgs...).
-		Values(valArgs...).
-		SuffixExpr(sq.Expr(upsertQuery)).
-		ToSql()
+		Values(valArgs...)
+
+	if len(key) > 0 {
+		keyColumns := slices.Collect(maps.Keys(key))
+		for i := range keyColumns {
+			keyColumns[i] = internal.WrapSQLIdent(keyColumns[i])
+		}
+
+		var setOnConflict []string
+		for column := range payload {
+			// tuples form a comma separated list, so they need a comma at the end.
+			// `EXCLUDED` references the new record's values. This will overwrite
+			// every column's value except for the key columns.
+			wrappedCol := internal.WrapSQLIdent(column)
+			tuple := fmt.Sprintf("%s=EXCLUDED.%s", wrappedCol, wrappedCol)
+			// add the tuple to the query string
+			setOnConflict = append(setOnConflict, tuple)
+		}
+
+		upsertQuery := fmt.Sprintf(
+			"ON CONFLICT (%s) DO UPDATE SET %s",
+			strings.Join(keyColumns, ","),
+			strings.Join(setOnConflict, ","),
+		)
+
+		stmt = stmt.Suffix(upsertQuery)
+	}
+
+	return stmt.ToSql()
 }
 
 // formatColumnsAndValues turns the key and payload into a slice of ordered
 // columns and values for upserting into Postgres.
-func (d *Destination) formatColumnsAndValues(ctx context.Context, table string, key, payload opencdc.StructuredData) ([]string, []interface{}, error) {
+func (d *Destination) formatColumnsAndValues(
+	ctx context.Context,
+	key, payload opencdc.StructuredData,
+	table string,
+) ([]string, []interface{}, error) {
 	var colArgs []string
 	var valArgs []interface{}
 
@@ -343,22 +281,51 @@ func (d *Destination) formatColumnsAndValues(ctx context.Context, table string,
 	return colArgs, valArgs, nil
 }
 
-// getKeyColumnName will return the name of the first item in the key or the
-// connector-configured default name of the key column name.
-func (d *Destination) getKeyColumnName(key opencdc.StructuredData, defaultKeyName string) string {
-	if len(key) > 1 {
-		// Go maps aren't order preserving, so anything over len 1 will have
-		// non-deterministic results until we handle composite keys.
-		panic("composite keys not yet supported")
+func (d *Destination) hasKey(e opencdc.Record) bool {
+	structuredKey, ok := e.Key.(opencdc.StructuredData)
+	if !ok {
+		return false
 	}
-	for k := range key {
-		return k
+	return len(structuredKey) > 0
+}
+
+// cleanRecord makes sure the record key and payload are structured data.
+func (d *Destination) cleanRecord(r opencdc.Record) (opencdc.Record, error) {
+	payloadAfter, err := d.structuredDataFormatter(r.Payload.After)
+	if err != nil {
+		return opencdc.Record{}, fmt.Errorf("failed to get structured data for .Payload.After: %w", err)
 	}
-	return defaultKeyName
+	key, err := d.structuredDataFormatter(r.Key)
+	if err != nil {
+		return opencdc.Record{}, fmt.Errorf("failed to get structured data for .Key: %w", err)
+	}
+
+	r.Key = key
+	r.Payload.After = payloadAfter
+	return r, nil
 }
 
-func (d *Destination) hasKey(e opencdc.Record) bool {
-	return e.Key != nil && len(e.Key.Bytes()) > 0
+func (d *Destination) structuredDataFormatter(data opencdc.Data) (opencdc.StructuredData, error) {
+	switch data := data.(type) {
+	case opencdc.StructuredData:
+		// already structured data, no need to convert
+		return data, nil
+	case opencdc.RawData:
+		raw := data.Bytes()
+		if len(raw) == 0 {
+			return opencdc.StructuredData{}, nil
+		}
+		m := make(map[string]interface{})
+		err := json.Unmarshal(raw, &m)
+		if err != nil {
+			return nil, fmt.Errorf("failed to JSON unmarshal raw data: %w", err)
+		}
+		return m, nil
+	case nil:
+		return opencdc.StructuredData{}, nil
+	default:
+		return nil, fmt.Errorf("unexpected data type %T, expected StructuredData or RawData", data)
+	}
 }
 
 func (d *Destination) formatValue(ctx context.Context, table string, column string, val interface{}) (interface{}, error) {

destination/config.go

@@ -36,8 +36,6 @@ type Config struct {
 	URL string `json:"url" validate:"required"`
 	// Table is used as the target table into which records are inserted.
 	Table string `json:"table" default:"{{ index .Metadata \"opencdc.collection\" }}"`
-	// Key represents the column name for the key used to identify and update existing rows.
-	Key string `json:"key"`
 }
 
 func (c *Config) Validate(ctx context.Context) error {