Add progress tracking and memory estimation for JDBC module

dataframe-jdbc/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/JdbcConfig.kt

@@ -0,0 +1,68 @@
+package org.jetbrains.kotlinx.dataframe.io
+
+/**
+ * Internal configuration for JDBC module behavior.
+ * Controlled via system properties or environment variables.
+ *
+ * Example usage:
+ * ```kotlin
+ * // Enable progress with detailed statistics
+ * System.setProperty("dataframe.jdbc.progress", "true")
+ * System.setProperty("dataframe.jdbc.progress.detailed", "true")
+ *
+ * // Or via environment variables
+ * export DATAFRAME_JDBC_PROGRESS=true
+ * export DATAFRAME_JDBC_PROGRESS_DETAILED=true
+ * ```
+ */
+internal object JdbcConfig {
+    /**
+     * Enable progress logging during data loading.
+     *
+     * When `true`, enables DEBUG-level progress messages and memory estimates.
+     * When `false` (default), only respects logger level (e.g., DEBUG).
+     *
+     * System property: `-Ddataframe.jdbc.progress=true`
+     * Environment variable: `DATAFRAME_JDBC_PROGRESS=true`
+     * Default: `false`
+     */
+    @JvmStatic
+    val PROGRESS_ENABLED: Boolean by lazy {
+        System.getProperty("dataframe.jdbc.progress")?.toBoolean()
+            ?: System.getenv("DATAFRAME_JDBC_PROGRESS")?.toBoolean()
+            ?: false
+    }
+
+    /**
+     * Enable detailed progress logging with statistics.
+     *
+     * When `true`: Shows row count, percentage, speed (rows/sec), memory usage
+     * When `false`: Shows only basic "Loaded X rows" messages
+     *
+     * Only takes effect when progress is enabled.
+     *
+     * System property: `-Ddataframe.jdbc.progress.detailed=true`
+     * Environment variable: `DATAFRAME_JDBC_PROGRESS_DETAILED=true`
+     * Default: `true`
+     */
+    @JvmStatic
+    val PROGRESS_DETAILED: Boolean by lazy {
+        System.getProperty("dataframe.jdbc.progress.detailed")?.toBoolean()
+            ?: System.getenv("DATAFRAME_JDBC_PROGRESS_DETAILED")?.toBoolean()
+            ?: true
+    }
+
+    /**
+     * Report progress every N rows.
+     *
+     * System property: `-Ddataframe.jdbc.progress.interval=5000`
+     * Environment variable: `DATAFRAME_JDBC_PROGRESS_INTERVAL=5000`
+     * Default: `1000`
+     */
+    @JvmStatic
+    val PROGRESS_INTERVAL: Int by lazy {
+        System.getProperty("dataframe.jdbc.progress.interval")?.toIntOrNull()
+            ?: System.getenv("DATAFRAME_JDBC_PROGRESS_INTERVAL")?.toIntOrNull()
+            ?: 1000
+    }
+}