Bigquery Sql vs Spark Sql - Memory Management
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I have been working on Bigquery standard sql a lot lately and the exact same data is being dealt with in spark at the same time .
I have noticed something strange in terms of query execution in bigquery though .
For Eg: If i fire a standard sql query with window analytic functions such as row_number() or rank() on a bigquery table that holds close to 500 GB data and around 60 million rows , it gives me a "Out of memory" error. And i read since window functions require sorting (partition by column name order by column name) , the bigquery engine forces the entire chunk of data into a single node for sorting purposes , which is understandable and hence the error .
But when i read the data into spark and fire the exact same query in spark sql after registering the dataset as a temptable , i get the output in a matter of minutes . I also notice the partitions and number of executors being active in the spark UI which basically means the data is being partitioned properly in spark .
Can anybody shed some light on why and how the 2 differ and in what way .
apache-spark-sql google-bigquery
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I have been working on Bigquery standard sql a lot lately and the exact same data is being dealt with in spark at the same time .
I have noticed something strange in terms of query execution in bigquery though .
For Eg: If i fire a standard sql query with window analytic functions such as row_number() or rank() on a bigquery table that holds close to 500 GB data and around 60 million rows , it gives me a "Out of memory" error. And i read since window functions require sorting (partition by column name order by column name) , the bigquery engine forces the entire chunk of data into a single node for sorting purposes , which is understandable and hence the error .
But when i read the data into spark and fire the exact same query in spark sql after registering the dataset as a temptable , i get the output in a matter of minutes . I also notice the partitions and number of executors being active in the spark UI which basically means the data is being partitioned properly in spark .
Can anybody shed some light on why and how the 2 differ and in what way .
apache-spark-sql google-bigquery
add a comment |
I have been working on Bigquery standard sql a lot lately and the exact same data is being dealt with in spark at the same time .
I have noticed something strange in terms of query execution in bigquery though .
For Eg: If i fire a standard sql query with window analytic functions such as row_number() or rank() on a bigquery table that holds close to 500 GB data and around 60 million rows , it gives me a "Out of memory" error. And i read since window functions require sorting (partition by column name order by column name) , the bigquery engine forces the entire chunk of data into a single node for sorting purposes , which is understandable and hence the error .
But when i read the data into spark and fire the exact same query in spark sql after registering the dataset as a temptable , i get the output in a matter of minutes . I also notice the partitions and number of executors being active in the spark UI which basically means the data is being partitioned properly in spark .
Can anybody shed some light on why and how the 2 differ and in what way .
apache-spark-sql google-bigquery
I have been working on Bigquery standard sql a lot lately and the exact same data is being dealt with in spark at the same time .
I have noticed something strange in terms of query execution in bigquery though .
For Eg: If i fire a standard sql query with window analytic functions such as row_number() or rank() on a bigquery table that holds close to 500 GB data and around 60 million rows , it gives me a "Out of memory" error. And i read since window functions require sorting (partition by column name order by column name) , the bigquery engine forces the entire chunk of data into a single node for sorting purposes , which is understandable and hence the error .
But when i read the data into spark and fire the exact same query in spark sql after registering the dataset as a temptable , i get the output in a matter of minutes . I also notice the partitions and number of executors being active in the spark UI which basically means the data is being partitioned properly in spark .
Can anybody shed some light on why and how the 2 differ and in what way .
apache-spark-sql google-bigquery
apache-spark-sql google-bigquery
asked Nov 24 '18 at 12:01
user1411837user1411837
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