表历史记录保留期取决于表设置delta.logRetentionDuration,后者默认为 30 天。 备注 按时间顺序查看和表历史记录由不同的保留期阈值控制。 请参阅什么是 Delta Lake 按时间顺序查看?。 SQL复制 DESCRIBEHISTORY'/data/events/'-- get the full history of the tableDESCRIBEHISTORY delta.`/data/events/`DESCRIBEHI...
用作源的 Delta 表结构化流式处理以增量方式读取 Delta 表。 当流式处理查询针对 Delta 表处于活动状态时,新表版本提交到源表时,新记录会以幂等方式处理。下面的代码示例演示如何使用表名或文件路径配置流式读取。PythonPython 复制 spark.readStream.table("table_name") spark.readStream.load("/path/to/...
When you run a DESCRIBE HISTORY query, the operationParameters column shows a clusterBy field by default for CREATE OR REPLACE and OPTIMIZE operations. For a Delta table that uses liquid clustering, the clusterBy field is populated with the table’s clustering columns. If the table does not ...
在Delta 數據表上選取除了標準 SELECT 選項之外,Delta 數據表還支援本節中所述的時間移動選項。 如需詳細資訊,請參閱 使用Delta Lake 數據表歷程記錄。AS OF 語法複製 table_identifier TIMESTAMP AS OF timestamp_expression table_identifier VERSION AS OF version timestamp_expression 可以是下列任一項: '2018...
您可以使用以下选项来指定Delta Lake流式处理源的起点,而无需处理整个表。 startingVersion:Delta Lake版本开始。从该版本(包括该版本)开始的所有表更改都将由流式处理源读取。您可以从命令“ DESCRIBE HISTORY events”输出的version列中获取提交版本。 要仅返回最新更改,请在Databricks Runtime 7.4及更高版本中指定la...
lastOperationDF = deltaTable.history(1) # get the last operation Scala %spark import io.delta.tables._ val deltaTable = DeltaTable.forPath(spark,pathToTable) val fullHistoryDF = deltaTable.history()// get the full history of the tableval lastOperationDF = deltaTable.history(1)// get th...
All tables created and updated by Delta Live Tables are Delta tables. Delta Lake time travel queries are supported only with Streaming tables, and arenotsupported with materialized views. SeeWork with Delta Lake table history. Delta Live Tables tables can only be defined once, meaning they can ...
Acquiring the knowledge and skills to operate a Delta table, including accessing its version history, restoring data, and utilizing time travel functionality using Spark and Databricks SQL. Understanding how to use Delta Cache to optimize query performance. Optional Lectures on AWS Integration: 'Setting...
If specified, the stream reads all changes to the Delta table starting with the specified version (inclusive). If the specified version is no longer available, the stream fails to start. You can obtain the commit versions from theversioncolumn of theDESCRIBE HISTORYcommand output. ...
Create a copy of the table with the DEEP CLONE command. DBFS_ROOT_NON_DELTA Non-delta tables persisted on the Databricks file system (dbfs). Create a copy of the table with a CREATE TABLE AS SELECT * FROM command. The UC table will be a Delta table. MANAGED Managed Hive metastore tabl...