feat: abstracción DB multi-engine — CRUD genérico y openers para SQLite, Postgres, ClickHouse, DuckDB

Funciones Go con interfaz unificada para operaciones DB: open, close, create_table, exec, query, insert_row, insert_batch.
Openers específicos por engine. Tipo DBConfig para configuración común.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

functions/infra/db_insert_batch.go

@@ -0,0 +1,70 @@
+package infra
+
+import (
+	"database/sql"
+	"fmt"
+	"strings"
+)
+
+// DBInsertBatch inserts multiple rows into a table using a prepared statement
+// inside a transaction. columns must match the order of values in each row.
+// Returns the total number of rows affected.
+// Column and table names are validated to contain only safe identifier chars.
+func DBInsertBatch(db *sql.DB, table string, columns []string, rows [][]any) (int64, error) {
+	if !validIdentifier.MatchString(table) {
+		return 0, fmt.Errorf("db_insert_batch: invalid table name %q", table)
+	}
+	if len(columns) == 0 {
+		return 0, fmt.Errorf("db_insert_batch: columns must not be empty")
+	}
+	if len(rows) == 0 {
+		return 0, nil
+	}
+
+	for _, col := range columns {
+		if !validIdentifier.MatchString(col) {
+			return 0, fmt.Errorf("db_insert_batch: invalid column name %q", col)
+		}
+	}
+
+	placeholders := make([]string, len(columns))
+	for i := range columns {
+		placeholders[i] = "?"
+	}
+	query := fmt.Sprintf(
+		"INSERT INTO %s (%s) VALUES (%s)",
+		table,
+		strings.Join(columns, ", "),
+		strings.Join(placeholders, ", "),
+	)
+
+	tx, err := db.Begin()
+	if err != nil {
+		return 0, fmt.Errorf("db_insert_batch: begin tx: %w", err)
+	}
+	defer tx.Rollback() //nolint:errcheck
+
+	stmt, err := tx.Prepare(query)
+	if err != nil {
+		return 0, fmt.Errorf("db_insert_batch: prepare: %w", err)
+	}
+	defer stmt.Close()
+
+	var total int64
+	for i, row := range rows {
+		if len(row) != len(columns) {
+			return 0, fmt.Errorf("db_insert_batch: row %d has %d values, expected %d", i, len(row), len(columns))
+		}
+		result, err := stmt.Exec(row...)
+		if err != nil {
+			return 0, fmt.Errorf("db_insert_batch: exec row %d: %w", i, err)
+		}
+		n, _ := result.RowsAffected()
+		total += n
+	}
+
+	if err := tx.Commit(); err != nil {
+		return 0, fmt.Errorf("db_insert_batch: commit: %w", err)
+	}
+	return total, nil
+}