History table
Table level commit log of a delta table. One row per version (transaction).
Every write (insert, update, delete, merge, optimize, schema change, and so on) creates a new numbered version.
Delta records each one as a JSON commit file in the table’s _delta_log/ folder, and DESCRIBE HISTORY reads that log and shows it as a table.
-- SQL
DESCRIBE HISTORY sales; -- all versions, newest first
DESCRIBE HISTORY sales LIMIT 5; -- last 5 commits
DESCRIBE HISTORY delta.`/mnt/data/sales`; -- by path
| Column | What it tells you |
|---|---|
version |
Commit number, starting at 0 and increasing by one per commit |
timestamp |
When the commit happened |
userId / userName |
Who made the change |
operation |
What happened: WRITE, MERGE, UPDATE, DELETE, OPTIMIZE, RESTORE, STREAMING UPDATE, ADD COLUMNS, … |
operationParameters |
Details of that operation, such as write mode, the predicate of a delete or merge, or partitionBy |
operationMetrics |
Numbers about the change: numOutputRows, numFiles, numTargetRowsUpdated, numTargetRowsDeleted, and so on |
readVersion |
The version the transaction read before writing |
isolationLevel |
Serializable or WriteSerializable |
isBlindAppend |
True if the write only appended without reading existing data |
job, notebook, clusterId |
Where the write came from (on Databricks) |
userMetadata |
A custom note you attached to the commit |
engineInfo |
The Spark/Delta version that wrote the commit |