亚洲地区驱动2016年全球SIM卡出货量增长至49亿

百度 本次踏青节将突出“赏西山晴雪，享生态成果”主题，通过踏青赏花季、京味文化民俗表演、西山无名英雄纪念广场宣传推广、摄影大赛、绘画大赛、森林教育和森林体验、森林定向越野、徒步登山、野生猛禽放飞等主题活动，丰富游园内容，服务市民观光游憩、休闲健身等多种需求。

Apache Iceberg is an open table format for huge analytic datasets. Iceberg adds tables to compute engines including Spark, Trino, PrestoDB, Flink, Hive and Impala using a high-performance table format that works just like a SQL table.

User experience

Iceberg avoids unpleasant surprises. Schema evolution works and won't inadvertently un-delete data. Users don't need to know about partitioning to get fast queries.

• Schema evolution supports add, drop, update, or rename, and has no side-effects
• Hidden partitioning prevents user mistakes that cause silently incorrect results or extremely slow queries
• Partition layout evolution can update the layout of a table as data volume or query patterns change
• Time travel enables reproducible queries that use exactly the same table snapshot, or lets users easily examine changes
• Version rollback allows users to quickly correct problems by resetting tables to a good state

Reliability and performance

Iceberg was built for huge tables. Iceberg is used in production where a single table can contain tens of petabytes of data and even these huge tables can be read without a distributed SQL engine.

• Scan planning is fast -- a distributed SQL engine isn't needed to read a table or find files
• Advanced filtering -- data files are pruned with partition and column-level stats, using table metadata

Iceberg was designed to solve correctness problems in eventually-consistent cloud object stores.

• Works with any cloud store and reduces NN congestion when in HDFS, by avoiding listing and renames
• Serializable isolation -- table changes are atomic and readers never see partial or uncommitted changes
• Multiple concurrent writers use optimistic concurrency and will retry to ensure that compatible updates succeed, even when writes conflict

Open standard

Iceberg has been designed and developed to be an open community standard with a specification to ensure compatibility across languages and implementations.

Apache Iceberg is open source, and is developed at the Apache Software Foundation.