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Demo: Time Travel

This demo shows Time Travel in action.

./bin/spark-shell \
  --packages io.delta:delta-core_2.12:1.0.0 \
  --conf spark.sql.extensions=io.delta.sql.DeltaSparkSessionExtension \
  --conf spark.sql.catalog.spark_catalog=org.apache.spark.sql.delta.catalog.DeltaCatalog
import io.delta.implicits._

Seq(("r1", 500), ("r2", 600)).toDF("id", "value").write.delta("/tmp/delta/demo")

sql("DESCRIBE HISTORY delta.`/tmp/delta/demo`").select('version, 'operation).show(truncate = false)

// +-------+---------+
// |version|operation|
// +-------+---------+
// |0      |WRITE    |
// +-------+---------+

sql("UPDATE delta.`/tmp/delta/demo` SET value = '700' WHERE id = 'r1'")

sql("DESCRIBE HISTORY delta.`/tmp/delta/demo`").select('version, 'operation).show(truncate = false)

// +-------+---------+
// |version|operation|
// +-------+---------+
// |1      |UPDATE   |
// |0      |WRITE    |
// +-------+---------+

spark.read.delta("/tmp/delta/demo").show

// +---+-----+
// | id|value|
// +---+-----+
// | r1|  700|
// | r2|  600|
// +---+-----+

spark.read.option("versionAsOf", 0).delta("/tmp/delta/demo").show

// +---+-----+
// | id|value|
// +---+-----+
// | r1|  500|
// | r2|  600|
// +---+-----+

The above query over a previous version is also possible using version pattern.

spark.read.delta("/tmp/delta/demo@v1").show

Last update: 2021-08-05
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