Merge pull request #2005 from ClickHouse/support-get-primary-keys

Update DatabaseMetaData.java to handle getPrimaryKeys

Author: Paultagoras

jdbc-v2/src/main/java/com/clickhouse/jdbc/metadata/DatabaseMetaData.java

@@ -909,10 +909,21 @@ public ResultSet getVersionColumns(String catalog, String schema, String table)
 
     @Override
     public ResultSet getPrimaryKeys(String catalog, String schema, String table) throws SQLException {
-        //Return an empty result set with the required columns
-        log.warn("getPrimaryKeys is not supported and may return invalid results");
         try {
-            return connection.createStatement().executeQuery("SELECT NULL AS TABLE_CAT, NULL AS TABLE_SCHEM, NULL AS TABLE_NAME, NULL AS COLUMN_NAME, NULL AS KEY_SEQ, NULL AS PK_NAME");
+            String sql = "SELECT NULL AS TABLE_CAT, " +
+                    "system.tables.database AS TABLE_SCHEM, " +
+                    "system.tables.name AS TABLE_NAME, " +
+                    "trim(c.1) AS COLUMN_NAME, " +
+                    "c.2 AS KEY_SEQ, " +
+                    "'PRIMARY' AS PK_NAME " +
+                    "FROM system.tables " +
+                    "ARRAY JOIN arrayZip(splitByChar(',', primary_key), arrayEnumerate(splitByChar(',', primary_key))) as c " +
+                    "WHERE system.tables.primary_key <> '' " +
+                    "AND system.tables.database ILIKE '" + (schema == null ? "%" : schema) + "' " +
+                    "AND system.tables.name ILIKE '" + (table == null ? "%" : table) + "' " +
+                    "ORDER BY COLUMN_NAME";
+            log.debug("getPrimaryKeys: %s", sql);
+            return connection.createStatement().executeQuery(sql);
         } catch (Exception e) {
             throw ExceptionUtils.toSqlState(e);
         }
@@ -923,7 +934,21 @@ public ResultSet getImportedKeys(String catalog, String schema, String table) th
         //Return an empty result set with the required columns
         log.warn("getImportedKeys is not supported and may return invalid results");
         try {
-            return connection.createStatement().executeQuery("SELECT NULL AS PKTABLE_CAT, NULL AS PKTABLE_SCHEM, NULL AS PKTABLE_NAME, NULL AS PKCOLUMN_NAME, NULL AS FKTABLE_CAT, NULL AS FKTABLE_SCHEM, NULL AS FKTABLE_NAME, NULL AS FKCOLUMN_NAME, NULL AS KEY_SEQ, NULL AS UPDATE_RULE, NULL AS DELETE_RULE, NULL AS FK_NAME, NULL AS PK_NAME, NULL AS DEFERRABILITY");
+            String sql = "SELECT NULL AS PKTABLE_CAT, " +
+                    "NULL AS PKTABLE_SCHEM, " +
+                    "NULL AS PKTABLE_NAME, " +
+                    "NULL AS PKCOLUMN_NAME, " +
+                    "NULL AS FKTABLE_CAT, " +
+                    "NULL AS FKTABLE_SCHEM, " +
+                    "NULL AS FKTABLE_NAME, " +
+                    "NULL AS FKCOLUMN_NAME, " +
+                    "NULL AS KEY_SEQ, " +
+                    "NULL AS UPDATE_RULE, " +
+                    "NULL AS DELETE_RULE, " +
+                    "NULL AS FK_NAME, " +
+                    "NULL AS PK_NAME, " +
+                    "NULL AS DEFERRABILITY LIMIT 0";
+            return connection.createStatement().executeQuery(sql);
         } catch (Exception e) {
             throw ExceptionUtils.toSqlState(e);
         }

jdbc-v2/src/test/java/com/clickhouse/jdbc/metadata/DatabaseMetaDataTest.java

@@ -98,16 +98,23 @@ public void testGetTables() throws Exception {
         }
     }
 
-    @Ignore("ClickHouse does not support primary keys")
+
     @Test(groups = { "integration" })
     public void testGetPrimaryKeys() throws Exception {
+        runQuery("SELECT 1;");
+        Thread.sleep(10 * 1000); // wait for query log to be updated
+
         try (Connection conn = getJdbcConnection()) {
             DatabaseMetaData dbmd = conn.getMetaData();
-            ResultSet rs = dbmd.getPrimaryKeys("system", null, "numbers");
+            ResultSet rs = dbmd.getPrimaryKeys(null, "system", "query_log");
             assertTrue(rs.next());
-            assertEquals(rs.getString("TABLE_NAME"), "numbers");
-            assertEquals(rs.getString("COLUMN_NAME"), "number");
+            assertEquals(rs.getString("TABLE_NAME"), "query_log");
+            assertEquals(rs.getString("COLUMN_NAME"), "event_date");
             assertEquals(rs.getShort("KEY_SEQ"), 1);
+            assertTrue(rs.next());
+            assertEquals(rs.getString("TABLE_NAME"), "query_log");
+            assertEquals(rs.getString("COLUMN_NAME"), "event_time");
+            assertEquals(rs.getShort("KEY_SEQ"), 2);
             assertFalse(rs.next());
         }
     }