Using CTAS and INSERT INTO to work around the 100 partition limit - Amazon Athena
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Using CTAS and INSERT INTO to work around the 100 partition limit

Athena has a limit of 100 partitions per CREATE TABLE AS SELECT (CTAS) query. Similarly, you can add a maximum of 100 partitions to a destination table with an INSERT INTO statement. This limit pertains only when the table is bucketed as well as partitioned.

If you exceed this limitation, you may receive the error message HIVE_TOO_MANY_OPEN_PARTITIONS: Exceeded limit of 100 open writers for partitions/buckets. To work around this limitation, you can use a CTAS statement and a series of INSERT INTO statements that create or insert up to 100 partitions each.

The example in this topic uses a database called tpch100 whose data resides in the Amazon S3 bucket location s3://<my-tpch-bucket>/.

To use CTAS and INSERT INTO to create a table of more than 100 partitions

  1. Use a CREATE EXTERNAL TABLE statement to create a table partitioned on the field that you want.

    The following example statement partitions the data by the column l_shipdate. The table has 2525 partitions.

    CREATE EXTERNAL TABLE `tpch100.lineitem_parq_partitioned`(
  `l_orderkey` int, 
  `l_partkey` int, 
  `l_suppkey` int, 
  `l_linenumber` int, 
  `l_quantity` double, 
  `l_extendedprice` double, 
  `l_discount` double, 
  `l_tax` double, 
  `l_returnflag` string, 
  `l_linestatus` string, 
  `l_commitdate` string, 
  `l_receiptdate` string, 
  `l_shipinstruct` string, 
  `l_comment` string)
PARTITIONED BY ( 
  `l_shipdate` string)
ROW FORMAT SERDE 
  'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe' STORED AS INPUTFORMAT 
  'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat' OUTPUTFORMAT 
  'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat' LOCATION   's3://<my-tpch-bucket>/lineitem/'

  2. Run a SHOW PARTITIONS <table_name> command like the following to list the partitions.

    SHOW PARTITIONS lineitem_parq_partitioned

    Following are partial sample results.

    /*
l_shipdate=1992-01-02
l_shipdate=1992-01-03
l_shipdate=1992-01-04
l_shipdate=1992-01-05
l_shipdate=1992-01-06

...

l_shipdate=1998-11-24
l_shipdate=1998-11-25
l_shipdate=1998-11-26
l_shipdate=1998-11-27
l_shipdate=1998-11-28
l_shipdate=1998-11-29
l_shipdate=1998-11-30
l_shipdate=1998-12-01
*/

  3. Run a CTAS query to create a partitioned table.

    The following example creates a table called my_lineitem_parq_partitioned and uses the WHERE clause to restrict the DATE to earlier than 1992-02-01. Because the sample dataset starts with January 1992, only partitions for January 1992 are created.

    CREATE table my_lineitem_parq_partitioned
WITH (partitioned_by = ARRAY['l_shipdate']) AS
SELECT l_orderkey,
         l_partkey,
         l_suppkey,
         l_linenumber,
         l_quantity,
         l_extendedprice,
         l_discount,
         l_tax,
         l_returnflag,
         l_linestatus,
         l_commitdate,
         l_receiptdate,
         l_shipinstruct,
         l_comment,
         l_shipdate
FROM tpch100.lineitem_parq_partitioned
WHERE cast(l_shipdate as timestamp) < DATE ('1992-02-01');

  4. Run the SHOW PARTITIONS command to verify that the table contains the partitions that you want.

    SHOW PARTITIONS my_lineitem_parq_partitioned;

    The partitions in the example are from January 1992.

    /*
l_shipdate=1992-01-02
l_shipdate=1992-01-03
l_shipdate=1992-01-04
l_shipdate=1992-01-05
l_shipdate=1992-01-06
l_shipdate=1992-01-07
l_shipdate=1992-01-08
l_shipdate=1992-01-09
l_shipdate=1992-01-10
l_shipdate=1992-01-11
l_shipdate=1992-01-12
l_shipdate=1992-01-13
l_shipdate=1992-01-14
l_shipdate=1992-01-15
l_shipdate=1992-01-16
l_shipdate=1992-01-17
l_shipdate=1992-01-18
l_shipdate=1992-01-19
l_shipdate=1992-01-20
l_shipdate=1992-01-21
l_shipdate=1992-01-22
l_shipdate=1992-01-23
l_shipdate=1992-01-24
l_shipdate=1992-01-25
l_shipdate=1992-01-26
l_shipdate=1992-01-27
l_shipdate=1992-01-28
l_shipdate=1992-01-29
l_shipdate=1992-01-30
l_shipdate=1992-01-31
*/

  5. Use an INSERT INTO statement to add partitions to the table.

    The following example adds partitions for the dates from the month of February 1992.

    INSERT INTO my_lineitem_parq_partitioned
SELECT l_orderkey,
         l_partkey,
         l_suppkey,
         l_linenumber,
         l_quantity,
         l_extendedprice,
         l_discount,
         l_tax,
         l_returnflag,
         l_linestatus,
         l_commitdate,
         l_receiptdate,
         l_shipinstruct,
         l_comment,
         l_shipdate
FROM tpch100.lineitem_parq_partitioned
WHERE cast(l_shipdate as timestamp) >= DATE ('1992-02-01')
AND cast(l_shipdate as timestamp) < DATE ('1992-03-01');

  6. Run SHOW PARTITIONS again.

    SHOW PARTITIONS my_lineitem_parq_partitioned;

    The sample table now has partitions from both January and February 1992.

    /*
l_shipdate=1992-01-02
l_shipdate=1992-01-03
l_shipdate=1992-01-04
l_shipdate=1992-01-05
l_shipdate=1992-01-06

...

l_shipdate=1992-02-20
l_shipdate=1992-02-21
l_shipdate=1992-02-22
l_shipdate=1992-02-23
l_shipdate=1992-02-24
l_shipdate=1992-02-25
l_shipdate=1992-02-26
l_shipdate=1992-02-27
l_shipdate=1992-02-28
l_shipdate=1992-02-29
*/

  7. Continue using INSERT INTO statements that read and add no more than 100 partitions each. Continue until you reach the number of partitions that you require.

    Important

    When setting the WHERE condition, be sure that the queries don't overlap. Otherwise, some partitions might have duplicated data.