Fix(connector): expose id_column, timestamp_column, metadata_columns for MySQL/PostgreSQL incremental sync (#13849)

### What problem does this PR solve?
The MySQL and PostgreSQL sync classes in `sync_data_source.py` were not
passing `id_column`, `timestamp_column`, and `metadata_columns` to
`RDBMSConnector`,
making incremental sync and document update impossible even when
configured.
   
- Without `id_column`: updated records generate new documents instead of
overwriting existing ones (doc ID is derived from content hash, so any
change produces a new ID).
- Without `timestamp_column`: `poll_source` always falls back to full
sync,
ignoring the configured time range.
- The three fields existed in the frontend default values but had no
form
inputs, so users had no way to fill them in.
### Type of change
  - [x] Bug Fix (non-breaking change which fixes an issue)        
  - [x] New Feature (non-breaking change which adds functionality)

### Changes
   
- **Backend** (`rag/svr/sync_data_source.py`): pass `id_column`,
    `timestamp_column`, and `metadata_columns` from `self.conf` to
`RDBMSConnector` for both `MySQL` and `PostgreSQL` sync classes.
- **Frontend**
(`web/src/pages/user-setting/data-source/constant/index.tsx`):
add `ID Column`, `Timestamp Column`, and `Metadata Columns` form fields
    to MySQL and PostgreSQL data source configuration UI with tooltips.

Signed-off-by: lixintao <lixintao@uniontech.com>
Co-authored-by: lixintao <lixintao@uniontech.com>

rag/svr/sync_data_source.py

@@ -1307,6 +1307,9 @@ class MySQL(SyncBase):
             database=self.conf.get("database", ""),
             query=self.conf.get("query", ""),
             content_columns=self.conf.get("content_columns", ""),
+            metadata_columns=self.conf.get("metadata_columns", ""),
+            id_column=self.conf.get("id_column") or None,
+            timestamp_column=self.conf.get("timestamp_column") or None,
             batch_size=self.conf.get("batch_size", INDEX_BATCH_SIZE),
         )
 
@@ -1343,6 +1346,9 @@ class PostgreSQL(SyncBase):
             database=self.conf.get("database", ""),
             query=self.conf.get("query", ""),
             content_columns=self.conf.get("content_columns", ""),
+            metadata_columns=self.conf.get("metadata_columns", ""),
+            id_column=self.conf.get("id_column") or None,
+            timestamp_column=self.conf.get("timestamp_column") or None,
             batch_size=self.conf.get("batch_size", INDEX_BATCH_SIZE),
         )
 

web/src/pages/user-setting/data-source/constant/index.tsx

@@ -936,6 +936,30 @@ export const DataSourceFormFields = {
       placeholder: 'title,description,content',
       tooltip: t('setting.mysqlContentColumnsTip'),
     },
+    {
+      label: 'Metadata Columns',
+      name: 'config.metadata_columns',
+      type: FormFieldType.Text,
+      required: false,
+      placeholder: 'id,category,status',
+      tooltip: t('setting.mysqlMetadataColumnsTip'),
+    },
+    {
+      label: 'ID Column',
+      name: 'config.id_column',
+      type: FormFieldType.Text,
+      required: false,
+      placeholder: 'id',
+      tooltip: t('setting.mysqlIdColumnTip'),
+    },
+    {
+      label: 'Timestamp Column',
+      name: 'config.timestamp_column',
+      type: FormFieldType.Text,
+      required: false,
+      placeholder: 'updated_at',
+      tooltip: t('setting.mysqlTimestampColumnTip'),
+    },
   ],
   [DataSourceKey.POSTGRESQL]: [
     {
@@ -986,6 +1010,30 @@ export const DataSourceFormFields = {
       placeholder: 'title,description,content',
       tooltip: t('setting.postgresqlContentColumnsTip'),
     },
+    {
+      label: 'Metadata Columns',
+      name: 'config.metadata_columns',
+      type: FormFieldType.Text,
+      required: false,
+      placeholder: 'id,category,status',
+      tooltip: t('setting.postgresqlMetadataColumnsTip'),
+    },
+    {
+      label: 'ID Column',
+      name: 'config.id_column',
+      type: FormFieldType.Text,
+      required: false,
+      placeholder: 'id',
+      tooltip: t('setting.postgresqlIdColumnTip'),
+    },
+    {
+      label: 'Timestamp Column',
+      name: 'config.timestamp_column',
+      type: FormFieldType.Text,
+      required: false,
+      placeholder: 'updated_at',
+      tooltip: t('setting.postgresqlTimestampColumnTip'),
+    },
   ],
 };