Here I am trying to simulate updates and deletes over a Hudi dataset and wish to see the state reflected in Athena table. We use EMR, S3 and Athena services of AWS.
Attempting Record Update with a withdrawal object
withdrawalID_mutate = 10382495
updateDF = final_df.filter(col("withdrawalID") == withdrawalID_mutate) \
.withColumn("accountHolderName", lit("Hudi_Updated"))
updateDF.write.format("hudi") \
.options(**hudi_options) \
.mode("append") \
.save(tablePath)
hudiDF = spark.read \
.format("hudi") \
.load(tablePath).filter(col("withdrawalID") == withdrawalID_mutate).show()
Shows the updated record but it is actually appended in the Athena table. Probably something to do with Glue Catalogue?
Attempting Record Delete
deleteDF = updateDF #deleting the updated record above
deleteDF.write.format("hudi") \
.option('hoodie.datasource.write.operation', 'upsert') \
.option('hoodie.datasource.write.payload.class', 'org.apache.hudi.common.model.EmptyHoodieRecordPayload') \
.options(**hudi_options) \
.mode("append") \
.save(tablePath)
still reflects the deleted record in the Athena table
Also tried using mode("overwrite") but as expected it deletes the older partitions and keeps only the latest.
Did anyone faced same issue and can guide in the right direction
Related
I want to run 'SHOW TABLES' statement through the spark-snowflake connector, I am running the spark on a Databricks platform and getting "Object 'SHOW' does not exist or not authorized" error.
df = spark.read \
.format("snowflake") \
.options(**options) \
.option("query", "show tables") \
.load()
df.show()
Sample query like "SELECT 1" is working as expected.
I know that I am able to install the native python-snowflake driver but I want to avoid this solution if possible because I already opened the session using spark.
There is also a way using "Utils.runQuery" function but I understood that is relevant only for DDL statement (It doesn't return the actual results).
Thanks!
When using DataFrames, the Snowflake connector supports SELECT queries only.
This is documented on our docs.
I'm using the following code to truncate a table before inserting data on it.
df.write \
.option("driver", "org.postgresql:postgresql:42.2.16") \
.option("truncate", True) \
.jdbc(url=pgsql_connection, table="service", mode='append', properties=properties_postgres)
Although, it is not working. The table still with old data. I'm using append since I don't want to the DB drop and create a new table everytime.
I've tried .option("truncate", "true") but not worked too.
I got no error messages. How can i solve this problem using .option to truncate my table.
You need to use overwrite mode
df.write \
.option("driver", "org.postgresql:postgresql:42.2.16") \
.option("truncate", True) \
.jdbc(url=pgsql_connection, table="service", mode='overwrite', properties=properties_postgres)
As given in documentation
https://spark.apache.org/docs/latest/sql-data-sources-jdbc.html
truncate: true -> When SaveMode.Overwrite is enabled, this option causes Spark to
truncate an existing table instead of dropping and recreating it.
I currently have an append table in databricks (spark 3, databricks 7.5)
parsedDf \
.select("somefield", "anotherField",'partition', 'offset') \
.write \
.format("delta") \
.mode("append") \
.option("mergeSchema", "true") \
.save(f"/mnt/defaultDatalake/{append_table_name}")
It was created with a create table command before and I don't use INSERT commands to write to it (as seen above)
Now I want to be able to use SQL logic to query it without everytime going through createOrReplaceTempView every time. Is is possible to add a table to the current data without removing it? what changes do I need to support this?
UPDATE:
I've tried:
res= spark.sql(f"CREATE TABLE exploration.oplog USING DELTA LOCATION '/mnt/defaultDataLake/{append_table_name}'")
But get an AnalysisException
You are trying to create an external table exploration.dataitems_oplog
from /mnt/defaultDataLake/specificpathhere using Databricks Delta, but the schema is not specified when the
input path is empty.
While the path isn't empty.
Starting with Databricks Runtime 7.0, you can create table in Hive metastore from the existing data, automatically discovering schema, partitioning, etc. (see documentation for all details). The base syntax is following (replace values in <> with actual values):
CREATE TABLE <database>.<table>
USING DELTA
LOCATION '/mnt/defaultDatalake/<append_table_name>'
P.S. there is more documentation on different aspects of the managed vs unmanaged tables that could be useful to read.
P.P.S. Works just fine for me on DBR 7.5ML:
I have two Spark streams set up in a notebook to run in parallel like so.
spark.sparkContext.setLocalProperty("spark.scheduler.pool", "pool1")
df1 = spark \
.readStream.format("delta") \
.table("test_db.table1") \
.select('foo', 'bar')
writer_df1 = df1.writeStream.option("checkpoint_location", checkpoint_location_1) \
.foreachBatch(
lambda batch_df, batch_epoch:
process_batch(batch_df, batch_epoch)
) \
.start()
spark.sparkContext.setLocalProperty("spark.scheduler.pool", "pool2")
df2 = spark \
.readStream.format("delta") \
.table("test_db.table2") \
.select('foo', 'bar')
writer_df2 = merchant_df.writeStream.option("checkpoint_location", checkpoint_location_2) \
.foreachBatch(
lambda batch_df, batch_epoch:
process_batch(batch_df, batch_epoch)
) \
.start()
These dataframes then get processed row by row, with each row being sent to an API. If the API call reports an error, I then convert the row into JSON and append this row to a common failures table in databricks.
columns = ['table_name', 'record', 'time_of_failure', 'error_or_status_code']
vals = [(table_name, json.dumps(row.asDict()), datetime.now(), str(error_or_http_code))]
error_df = spark.createDataFrame(vals, columns)
error_df.select('table_name','record','time_of_failure', 'error_or_status_code').write.format('delta').mode('Append').saveAsTable("failures_db.failures_db)"
When attempting to add the row to this table, the saveAsTable() call here throws the following exception.
py4j.protocol.Py4JJavaError: An error occurred while calling o3578.saveAsTable.
: java.lang.IllegalStateException: Cannot find the REPL id in Spark local properties. Spark-submit and R doesn't support transactional writes from different clusters. If you are using R, please switch to Scala or Python. If you are using spark-submit , please convert it to Databricks JAR job. Or you can disable multi-cluster writes by setting 'spark.databricks.delta.multiClusterWrites.enabled' to 'false'. If this is disabled, writes to a single table must originate from a single cluster. Please check https://docs.databricks.com/delta/delta-intro.html#frequently-asked-questions-faq for more details.
If I comment out one of the streams and re-run the notebook, any errors from the API calls get inserted into the table with no issues. I feel like there's some configuration I need to add but am not sure of where to go from here.
Not sure if this is the best solution, but I believe the problem comes from each stream writing to the table at the same time. I split this table into separate tables for each stream and it worked after that.
Specifically when I'm reading from an existing Redshift table, how can I specify the format it will use during the load to the temporary directory?
My load looks like this:
data = spark.read.format('com.databricks.spark.redshift') \
.option('url', REDSHIFT_URL_DEV) \
.option('dbtable', 'ods_misc.requests_2014_04') \
.option('tempdir', REDSHIFT_WEBLOG_DIR + '/2014_04') \
.load()
When I look at the data from the default load it looks like csv where it splits the columns across multiple files, so for example col1 col2... are in 0000_part1 and so on.