datart 服务端聚合以及http 和 file 开启缓存过程

-执行 execute 或者 /execute/test都会执行到ProviderManager 的run 方法

    public Dataframe run(DataProviderSource source, QueryScript queryScript, ExecuteParam param) throws Exception {
    //source 的 type 为 jdbc 或者http 、file 
        Dataframe dataframe = getDataProviderService(source.getType()).execute(source, queryScript, param);
        excludeColumns(dataframe, param.getIncludeColumns());
        return dataframe;
    }

• 如果是jdbc 调用JdbcDataProvider#execute

    public Dataframe execute(DataProviderSource source, QueryScript script, ExecuteParam executeParam) throws Exception {
        JdbcDataProviderAdapter adapter = matchProviderAdapter(source);
        //If server aggregation is enabled, query the full data before performing server aggregation
        //如果开启服务端聚合
        if (executeParam.isServerAggregate()) {
        
            return adapter.executeInLocal(script, executeParam);
        } else {
        //如果不开启则调用原始的数据库执行
            return adapter.executeOnSource(script, executeParam);
        }
    }

    public Dataframe executeInLocal(QueryScript script, ExecuteParam executeParam) throws Exception {
        SqlScriptRender render = new SqlScriptRender(script
                , executeParam
                , getSqlDialect());
         //生成原始的sql       
        String sql = render.render(false, false, false);
        //执行sql 获取结果
        Dataframe data = execute(sql);
        if (!CollectionUtils.isEmpty(script.getSchema())) {
            for (Column column : data.getColumns()) {
                column.setType(script.getSchema().getOrDefault(column.getName(), column).getType());
            }
        }
        data.setName(script.toQueryKey());
        return LocalDB.executeLocalQuery(null, executeParam, Dataframes.of(script.getSourceId(), data));
    }

	//此方法仅为jdbc调用
    public static Dataframe executeLocalQuery(QueryScript queryScript, ExecuteParam executeParam, Dataframes dataframes) throws Exception {
    //复用下面一个方法 persistent 传false
        return executeLocalQuery(queryScript, executeParam, dataframes, false, null);
    }

    public static Dataframe executeLocalQuery(QueryScript queryScript, ExecuteParam executeParam, Dataframes dataframes, boolean persistent, Date expire) throws Exception {
        if (queryScript == null) {
            // 直接以指定数据源为表进行查询，生成一个默认的SQL查询全部数据
            queryScript = new QueryScript();
            queryScript.setScript(String.format(SELECT_START_SQL, dataframes.getDataframes().get(0).getName()));
            queryScript.setVariables(Collections.emptyList());
            queryScript.setSourceId(dataframes.getKey());
        }
		//获取url 如果persistent 是true 则 使用h2:file 否则 使用h2:mem
        String url = getConnectionUrl(persistent, dataframes.getKey());
        synchronized (url.intern()) {
        //根据persistent 判断使用那种方式 ，jdbc 只会传false
            return persistent ? executeInLocalDB(queryScript, executeParam, dataframes, expire) : executeInMemDB(queryScript, executeParam, dataframes);
        }
    }

• 基于mem

  private static Dataframe executeInMemDB(QueryScript queryScript, ExecuteParam executeParam, Dataframes dataframes) throws Exception {
        Connection connection = getConnection(false, dataframes.getKey());
        try {
            for (Dataframe dataframe : dataframes.getDataframes()) {
            //调用h2保存
                registerDataAsTable(dataframe, connection);
            }
            return execute(connection, queryScript, executeParam);
        } finally {
            try {
                connection.close();
            } catch (Exception e) {
                log.error("connection close error ", e);
            }
            for (Dataframe df : dataframes.getDataframes()) {
                unregisterData(df.getId());
            }
        }

    }