feat: enhance column metadata retrieval across database sources

- Add support for capturing source type (table, view, materialized view)
- Improve column metadata queries for Postgres, MySQL, BigQuery, and Snowflake
- Include more comprehensive column information during dataset import
- Extend DatasetColumnRecord to include source_type field

api/src/utils/query_engine/import_dataset_columns.rs

@@ -26,6 +26,7 @@ pub struct DatasetColumnRecord {
     pub type_: String,
     pub nullable: bool,
     pub comment: Option<String>,
+    pub source_type: String,
 }
 
 pub async fn import_dataset_columns(
@@ -143,39 +144,76 @@ async fn get_postgres_columns(
     schema_name: &String,
     credentials: &PostgresCredentials,
 ) -> Result<Vec<DatasetColumnRecord>> {
-    let (postgres_conn, child_process, tempfile) = match get_postgres_connection(credentials).await
-    {
+    let (postgres_conn, child_process, tempfile) = match get_postgres_connection(credentials).await {
         Ok(conn) => conn,
         Err(e) => return Err(e),
     };
 
-    let sql = format!("SELECT
-    c.column_name as name,
-    c.data_type as type_,
-    CASE WHEN c.is_nullable = 'YES' THEN true ELSE false END as nullable,
-    pgd.description AS comment
-FROM
-    information_schema.columns c
-LEFT JOIN
-    pg_catalog.pg_statio_all_tables as st on c.table_schema = st.schemaname and c.table_name = st.relname
-LEFT JOIN
-    pg_catalog.pg_description pgd on pgd.objoid = st.relid and pgd.objsubid = c.ordinal_position
-WHERE
-    c.table_name = '{dataset_name}'
-    AND c.table_schema = '{schema_name}'
-ORDER BY
-    c.table_schema,
-    c.table_name,
-    c.ordinal_position;"
+    // Query for tables and views
+    let regular_sql = format!(
+        "SELECT
+            c.column_name as name,
+            c.data_type as type_,
+            CASE WHEN c.is_nullable = 'YES' THEN true ELSE false END as nullable,
+            pgd.description AS comment,
+            t.table_type as source_type
+        FROM
+            information_schema.columns c
+        JOIN
+            information_schema.tables t ON c.table_name = t.table_name AND c.table_schema = t.table_schema
+        LEFT JOIN
+            pg_catalog.pg_statio_all_tables as st on c.table_schema = st.schemaname and c.table_name = st.relname
+        LEFT JOIN
+            pg_catalog.pg_description pgd on pgd.objoid = st.relid and pgd.objsubid = c.ordinal_position
+        WHERE
+            c.table_name = '{dataset_name}'
+            AND c.table_schema = '{schema_name}'
+            AND t.table_type IN ('BASE TABLE', 'VIEW')
+        ORDER BY
+            c.ordinal_position;"
     );
 
-    let cols = match sqlx::query_as::<_, DatasetColumnRecord>(&sql)
+    // Query for materialized views
+    let mv_sql = format!(
+        "SELECT 
+            a.attname as name,
+            format_type(a.atttypid, a.atttypmod) as type_,
+            NOT a.attnotnull as nullable,
+            d.description as comment,
+            'MATERIALIZED_VIEW' as source_type
+        FROM pg_class c
+        JOIN pg_namespace n ON n.oid = c.relnamespace
+        JOIN pg_attribute a ON a.attrelid = c.oid
+        LEFT JOIN pg_description d ON d.objoid = c.oid AND d.objsubid = a.attnum
+        WHERE c.relkind = 'm'
+        AND n.nspname = '{schema_name}'
+        AND c.relname = '{dataset_name}'
+        AND a.attnum > 0
+        AND NOT a.attisdropped
+        ORDER BY a.attnum;"
+    );
+
+    let mut cols = Vec::new();
+
+    // Get regular tables and views
+    let regular_cols = match sqlx::query_as::<_, DatasetColumnRecord>(&regular_sql)
         .fetch_all(&postgres_conn)
         .await
     {
-        Ok(cols) => cols,
-        Err(e) => return Err(anyhow!("Error fetching columns: {:?}", e)),
+        Ok(c) => c,
+        Err(e) => return Err(anyhow!("Error fetching regular columns: {:?}", e)),
     };
+    cols.extend(regular_cols);
+
+    // Get materialized view columns
+    let mv_cols = match sqlx::query_as::<_, DatasetColumnRecord>(&mv_sql)
+        .fetch_all(&postgres_conn)
+        .await
+    {
+        Ok(c) => c,
+        Err(e) => return Err(anyhow!("Error fetching materialized view columns: {:?}", e)),
+    };
+    cols.extend(mv_cols);
 
     if let (Some(mut child_process), Some(tempfile)) = (child_process, tempfile) {
         child_process.kill()?;
@@ -198,16 +236,19 @@ async fn get_mysql_columns(
 
     let sql = format!(
         "SELECT
-            CAST(COLUMN_NAME AS CHAR) as name,
-            CAST(DATA_TYPE AS CHAR) as type_,
-            CASE WHEN IS_NULLABLE = 'YES' THEN true ELSE false END as nullable,
-            CAST(COLUMN_COMMENT AS CHAR) as comment
+            CAST(c.COLUMN_NAME AS CHAR) as name,
+            CAST(c.DATA_TYPE AS CHAR) as type_,
+            CASE WHEN c.IS_NULLABLE = 'YES' THEN true ELSE false END as nullable,
+            CAST(c.COLUMN_COMMENT AS CHAR) as comment,
+            CAST(t.TABLE_TYPE AS CHAR) as source_type
         FROM
-            INFORMATION_SCHEMA.COLUMNS
+            INFORMATION_SCHEMA.COLUMNS c
+        JOIN
+            INFORMATION_SCHEMA.TABLES t ON c.TABLE_NAME = t.TABLE_NAME AND c.TABLE_SCHEMA = t.TABLE_SCHEMA
         WHERE
-            TABLE_NAME = '{}'
+            c.TABLE_NAME = '{}'
         ORDER BY
-            ORDINAL_POSITION;",
+            c.ORDINAL_POSITION;",
         dataset_name
     );
 
@@ -234,14 +275,35 @@ async fn get_bigquery_columns(
 
     let sql = format!(
         r#"
-        SELECT
-            column_name AS name,
-            data_type AS type_,
-            is_nullable = 'YES' AS nullable
-        FROM `region-us`.INFORMATION_SCHEMA.COLUMNS
-        WHERE table_name = '{dataset_name}'
+        WITH all_columns AS (
+            -- Regular tables and views
+            SELECT
+                column_name AS name,
+                data_type AS type_,
+                is_nullable = 'YES' AS nullable,
+                NULL as comment,
+                table_type as source_type
+            FROM `region-us`.INFORMATION_SCHEMA.COLUMNS c
+            JOIN `region-us`.INFORMATION_SCHEMA.TABLES t 
+                USING(table_name, table_schema)
+            WHERE table_name = '{dataset_name}'
+            
+            UNION ALL
+            
+            -- Materialized views specific metadata if needed
+            SELECT
+                column_name AS name,
+                data_type AS type_,
+                is_nullable = 'YES' AS nullable,
+                NULL as comment,
+                'MATERIALIZED_VIEW' as source_type
+            FROM `region-us`.INFORMATION_SCHEMA.MATERIALIZED_VIEWS mv
+            JOIN `region-us`.INFORMATION_SCHEMA.COLUMNS c 
+                USING(table_name, table_schema)
+            WHERE mv.table_name = '{dataset_name}'
+        )
+        SELECT * FROM all_columns
         "#,
-        dataset_name = dataset_name
     );
 
     let query_request = QueryRequest {
@@ -256,7 +318,7 @@ async fn get_bigquery_columns(
         .job()
         .query(&project_id, query_request)
         .await
-        .map_err(|e| anyhow!("Error fetching table and views records: {:?}", e))?;
+        .map_err(|e| anyhow!("Error fetching columns: {:?}", e))?;
 
     let mut columns = Vec::new();
 
@@ -284,11 +346,25 @@ async fn get_bigquery_columns(
                     .ok_or_else(|| anyhow!("Missing nullable value"))?
                     .parse::<bool>()?;
 
+                let comment = cols[3]
+                    .value
+                    .as_ref()
+                    .and_then(|v| v.as_str())
+                    .map(|s| s.to_string());
+
+                let source_type = cols[4]
+                    .value
+                    .as_ref()
+                    .and_then(|v| v.as_str())
+                    .ok_or_else(|| anyhow!("Missing source type"))?
+                    .to_string();
+
                 columns.push(DatasetColumnRecord {
                     name,
                     type_,
                     nullable,
-                    comment: None,
+                    comment,
+                    source_type,
                 });
             }
         }
@@ -306,18 +382,44 @@ async fn get_snowflake_columns(
     let uppercase_dataset_name = dataset_name.to_uppercase();
 
     let sql = format!(
-        "SELECT
-            COLUMN_NAME AS name,
-            DATA_TYPE AS type_,
-            CASE WHEN IS_NULLABLE = 'YES' THEN true ELSE false END AS nullable,
-            COMMENT AS comment
-        FROM
-            INFORMATION_SCHEMA.COLUMNS
-        WHERE
-            TABLE_NAME = '{}'
-        ORDER BY
-            ORDINAL_POSITION;",
-        uppercase_dataset_name
+        "WITH all_objects AS (
+            -- Regular tables and views
+            SELECT
+                c.COLUMN_NAME AS name,
+                c.DATA_TYPE AS type_,
+                CASE WHEN c.IS_NULLABLE = 'YES' THEN true ELSE false END AS nullable,
+                c.COMMENT AS comment,
+                t.TABLE_TYPE as source_type
+            FROM
+                INFORMATION_SCHEMA.COLUMNS c
+            JOIN 
+                INFORMATION_SCHEMA.TABLES t 
+                ON c.TABLE_NAME = t.TABLE_NAME 
+                AND c.TABLE_SCHEMA = t.TABLE_SCHEMA
+            WHERE
+                c.TABLE_NAME = '{uppercase_dataset_name}'
+            
+            UNION ALL
+            
+            -- Materialized views
+            SELECT
+                c.COLUMN_NAME AS name,
+                c.DATA_TYPE AS type_,
+                CASE WHEN c.IS_NULLABLE = 'YES' THEN true ELSE false END AS nullable,
+                c.COMMENT AS comment,
+                'MATERIALIZED_VIEW' as source_type
+            FROM
+                INFORMATION_SCHEMA.COLUMNS c
+            JOIN 
+                INFORMATION_SCHEMA.VIEWS v
+                ON c.TABLE_NAME = v.TABLE_NAME 
+                AND c.TABLE_SCHEMA = v.TABLE_SCHEMA
+            WHERE
+                c.TABLE_NAME = '{uppercase_dataset_name}'
+                AND v.IS_MATERIALIZED = 'YES'
+        )
+        SELECT * FROM all_objects
+        ORDER BY name;",
     );
 
     // Execute the query using the Snowflake client
@@ -385,6 +487,7 @@ async fn get_snowflake_columns(
                     type_,
                     nullable,
                     comment,
+                    source_type: "TABLE".to_string(),
                 });
             }
         }