fix(ers): use pgx database/sql driver in SQL ERS provider

service/entityresolution/multi-strategy/README.md

@@ -691,4 +691,4 @@ See [`example-config.yaml`](./example-config.yaml) for a comprehensive configura
 - Cross-backend failover scenarios
 - Health check configuration
 
-For implementation details and architecture decisions, see the [Multi-Strategy ERS ADR](../../../adr/decisions/2025-07-31-multi-strategy-entity-resolution-service.md).
+For implementation details and architecture decisions, see the [Multi-Strategy ERS ADR](../../../adr/decisions/2025-07-31-multi-strategy-entity-resolution-service.md).

service/entityresolution/multi-strategy/example-config.yaml

@@ -276,4 +276,4 @@ services:
 #
 # 5. No matching strategy:
 #    - JWT contains: {"aud": ["unknown"]}
-#    - Result: Error - no matching strategy found (regardless of failure_strategy)
+#    - Result: Error - no matching strategy found (regardless of failure_strategy)

service/entityresolution/multi-strategy/providers/sql/sql_config.go

@@ -6,6 +6,10 @@ import (
 
 const (
 	// Default SQL configuration values
+	defaultPostgreSQLDriver   = "postgres"
+	canonicalPGXDriver        = "pgx/v5"
+	pgxDriverAlias            = "pgx"
+	postgresQLDriverAlias     = "postgresql"
 	defaultPostgreSQLPort     = 5432
 	defaultMaxOpenConnections = 25
 	defaultMaxIdleConnections = 5
@@ -17,7 +21,7 @@ const (
 // SQLConfig defines configuration for SQL database providers
 type Config struct {
 	// Database connection configuration
-	Driver   string `mapstructure:"driver"` // "postgres", "mysql", "sqlite"
+	Driver   string `mapstructure:"driver"` // "postgres", "mysql", "sqlite" ("pgx", "pgx/v5", and "postgresql" are accepted as aliases)
 	Host     string `mapstructure:"host"`
 	Port     int    `mapstructure:"port"`
 	Database string `mapstructure:"database"`
@@ -45,7 +49,7 @@ type Config struct {
 // DefaultConfig returns a default SQL configuration
 func DefaultConfig() Config {
 	return Config{
-		Driver:             "postgres",
+		Driver:             defaultPostgreSQLDriver,
 		Port:               defaultPostgreSQLPort,
 		SSLMode:            "require",
 		MaxOpenConnections: defaultMaxOpenConnections,

service/entityresolution/multi-strategy/providers/sql/sql_config_test.go

@@ -0,0 +1,76 @@
+package sql
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDefaultConfigUsesPostgreSQLDriver(t *testing.T) {
+	config := DefaultConfig()
+	require.Equal(t, defaultPostgreSQLDriver, config.Driver)
+}
+
+func TestNormalizeDriverName(t *testing.T) {
+	tests := []struct {
+		name   string
+		driver string
+		want   string
+	}{
+		{
+			name:   "pgx",
+			driver: pgxDriverAlias,
+			want:   canonicalPGXDriver,
+		},
+		{
+			name:   "postgres default",
+			driver: defaultPostgreSQLDriver,
+			want:   canonicalPGXDriver,
+		},
+		{
+			name:   "postgresql alias with whitespace and case",
+			driver: " PostgreSQL ",
+			want:   canonicalPGXDriver,
+		},
+		{
+			name:   "other driver",
+			driver: "mysql",
+			want:   "mysql",
+		},
+		{
+			name:   "sqlite driver",
+			driver: "sqlite3",
+			want:   "sqlite3",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.want, normalizeDriverName(tt.driver))
+		})
+	}
+}
+
+func TestBuildConnectionStringSupportsPostgresAliases(t *testing.T) {
+	tests := []string{canonicalPGXDriver, defaultPostgreSQLDriver, pgxDriverAlias, postgresQLDriverAlias, "Postgres"}
+
+	for _, driver := range tests {
+		t.Run(driver, func(t *testing.T) {
+			provider := &Provider{
+				config: Config{
+					Driver:   driver,
+					Host:     "localhost",
+					Port:     5432,
+					Database: "identity_db",
+					Username: "ers_user",
+					Password: "ers_password",
+					SSLMode:  "require",
+				},
+			}
+
+			connStr, err := provider.buildConnectionString()
+			require.NoError(t, err)
+			require.Contains(t, connStr, "dbname=identity_db")
+		})
+	}
+}

service/entityresolution/multi-strategy/providers/sql/sql_provider.go

@@ -6,14 +6,21 @@ import (
 	"fmt"
 	"strings"
 
-	// Database drivers would be imported here:
-	// _ "github.com/lib/pq"           // PostgreSQL driver
-	// _ "github.com/go-sql-driver/mysql" // MySQL driver
-	// _ "github.com/mattn/go-sqlite3" // SQLite driver
-
+	// Register the pgx/v5 database/sql driver for SQL providers.
+	_ "github.com/jackc/pgx/v5/stdlib"
 	"github.com/opentdf/platform/service/entityresolution/multi-strategy/types"
 )
 
+func normalizeDriverName(driver string) string {
+	driver = strings.ToLower(strings.TrimSpace(driver))
+	switch driver {
+	case defaultPostgreSQLDriver, pgxDriverAlias, postgresQLDriverAlias:
+		return canonicalPGXDriver
+	default:
+		return driver
+	}
+}
+
 // Provider implements the Provider interface for SQL databases
 type Provider struct {
 	name   string
@@ -24,6 +31,10 @@ type Provider struct {
 
 // NewProvider creates a new SQL provider
 func NewProvider(ctx context.Context, name string, config Config) (*Provider, error) {
+	// Normalize aliases so "pgx", "postgres", and "postgresql" use the
+	// registered pgx/v5 database/sql driver name.
+	config.Driver = normalizeDriverName(config.Driver)
+
 	provider := &Provider{
 		name:   name,
 		config: config,
@@ -253,8 +264,8 @@ func (p *Provider) Close() error {
 
 // buildConnectionString creates a connection string based on the driver
 func (p *Provider) buildConnectionString() (string, error) {
-	switch strings.ToLower(p.config.Driver) {
-	case "postgres":
+	switch normalizeDriverName(p.config.Driver) {
+	case canonicalPGXDriver:
 		return fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s sslmode=%s",
 			p.config.Host, p.config.Port, p.config.Username, p.config.Password,
 			p.config.Database, p.config.SSLMode), nil