Databricks Delta Transaction Log file

Question

Hello:

I have a container in ADLS Gen2 where I have __delta__log file and the rest of the parquet files.

I want to parse and read this __delta__log file in Azure Synapse to understand the time modification of files, timestamps, metadata, and other information.

Any help on how to do that or any link or blog that can walk me thru with some coding is greatly appreciated.

Thanking in advance.

Answer 1

@Jayesh Dave - Thanks for the question and using MS Q&A platform.

To read and parse the __delta__log file in Azure Synapse, you can use Azure Synapse Spark to read the file and extract the required information. Here are the steps you can follow:

• Create a new Synapse workspace and open Synapse Studio.
• Create a new notebook and select the Spark pool you want to use.
• In the first cell, you can use the following code to read the __delta__log file:

from pyspark.sql.functions import *
from pyspark.sql.types import *

delta_log = spark.read.format("delta").load("<path_to_delta_log_file>")

Replace <path_to_delta_log_file> with the path to your __delta__log file in ADLS Gen2.

• Once you have loaded the __delta__log file, you can use Spark SQL to query the data and extract the required information. For example, you can use the following code to get the timestamp of the latest modification:

latest_timestamp = delta_log.select(max(col("timestamp"))).collect()[0][0]

This will return the latest timestamp in the __delta__log file.

• You can also use Spark SQL to join the __delta__log file with the parquet files to get more information about the modifications. For example, you can use the following code to join the __delta__log file with a parquet file:

parquet_file = spark.read.format("parquet").load("<path_to_parquet_file>")
joined_data = delta_log.join(parquet_file, delta_log.id == parquet_file.id)

Replace <path_to_parquet_file> with the path to your parquet file in ADLS Gen2.

• Once you have joined the data, you can use Spark SQL to query the data and extract the required information.

Hope this helps. Do let us know if you any further queries.

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