如下面的Snowflake Query Profiler截图所示,速度快的主要原因在于:该查询只扫描了整个16Gb压缩数据中的1.5Mb,而且除了一个微分区之外,它几乎跳过了所有不相关的内容。 可见,只要使用到了聚类密钥,Snowflake就能够跳过多达99.91%的数据,进而避免了任何与需要维护传统索引相关的性能、以及数据管理的开销。 结论 综上所述,...
Cloud Service 层是使得可以在数据上进行数据定义语言(DDL)和数据操作语言(DML)操作的SQL客户端接口的核心。 The Query Processing (Virtual Warehouse) Compute Layer Snowflake 的计算集群,通常也叫做虚拟数仓(Virtual Warehouse),是一个由 CPU、内存、和临时存储组成的动态资源集群,用户可以自由创建计算集群,Snowflake...
Note that ClickHouse's query cache is node specific and not transactionally consistent, making it better suited to real-time analytics. Users also have granular control over its use with the ability to control its use on a per-query basis, its precise size, whether a query is cached (...
Snowflake教程1：关于教程说明书
Let’s first ask the model to generate a SQL query: SQL generation example with Snowflake Arctic. For comparison purposes, let’s submit the same request to ChatGPT-4o: SQL generation example with ChatGPT-4o. Notice that it generated the same result (with cleaner formatting). We can conc...
lru_cache_info: Dict[str, Dict[str, int]] = field(default_factory=dict) data_dictionary_cache: Optional["SnowflakeDataDictionary"] = None # These will be non-zero if snowflake information_schema queries fail with error - # "Information schema query returned too much data. Please repeat qu...
Persisted query results Similar to tables, the query results for external tablespersistfor 24 hours. Within this 24-hour period, the following operations invalidate and purge the query result cache for external tables: Any DDL operation that modifies the external table definition. This includes explic...
-- at the session level ALTER SESSION SET DOTNET_QUERY_RESULT_FORMAT = ARROW; -- or at the user level ALTER USER SET DOTNET_QUERY_RESULT_FORMAT = ARROW; -- or at the account level ALTER ACCOUNT SET DOTNET_QUERY_RESULT_FORMAT = ARROW; The valid values for the parameter are: ARROW...
so that the query at timestamp Z will read different set of blocks than the query at timestamp X. Old blocks can be stored for 90+ days, if you have enough money to afford it as you will be billed for the cloud storage use of the old blocks. Expired blocks are automatically cleaned...
整个系统的并发执行能力很重要,这样能通过弹性地扩展 VW 数量或者大小,在按小时收费下价格近似的同时,能够尽量快地完成 Query 执行、数据导入任务,实现极度友好的用户体验。 尽可能地利用 VW 本地的 local disk 做 cache,因此对于每个 VW 所负责的文件集合最好是固定的。这也是 Snowflake 优化方向上最重要的部分之...