This is a quick blog post to show how minor and major compaction for Hive transactional tables occurs. Let’s use the situation that the hive acid transactions with partitions (a behind the scenes perspective) post leaves us in. Here it is!
$ hdfs dfs -ls -R /wa/t/m/h/try_it drwxrwx---+ - hive hadoop 0 2019-12-12 09:57 /wa/t/m/h/try_it/prt=p1 drwxrwx---+ - hive hadoop 0 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p1/delete_delta_0000003_0000003_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p1/delete_delta_0000003_0000003_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 733 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p1/delete_delta_0000003_0000003_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 09:57 /wa/t/m/h/try_it/prt=p1/delete_delta_0000005_0000005_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:57 /wa/t/m/h/try_it/prt=p1/delete_delta_0000005_0000005_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 733 2019-12-12 09:57 /wa/t/m/h/try_it/prt=p1/delete_delta_0000005_0000005_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 07:43 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000001_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 07:43 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000001_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 788 2019-12-12 07:43 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000001_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p1/delta_0000003_0000003_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p1/delta_0000003_0000003_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 816 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p1/delta_0000003_0000003_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 09:45 /wa/t/m/h/try_it/prt=p2 drwxrwx---+ - hive hadoop 0 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p2/delete_delta_0000003_0000003_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p2/delete_delta_0000003_0000003_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 727 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p2/delete_delta_0000003_0000003_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 09:45 /wa/t/m/h/try_it/prt=p2/delete_delta_0000004_0000004_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:44 /wa/t/m/h/try_it/prt=p2/delete_delta_0000004_0000004_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 733 2019-12-12 09:44 /wa/t/m/h/try_it/prt=p2/delete_delta_0000004_0000004_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 08:15 /wa/t/m/h/try_it/prt=p2/delta_0000002_0000002_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 08:15 /wa/t/m/h/try_it/prt=p2/delta_0000002_0000002_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 788 2019-12-12 08:15 /wa/t/m/h/try_it/prt=p2/delta_0000002_0000002_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p2/delta_0000003_0000003_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p2/delta_0000003_0000003_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 816 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p2/delta_0000003_0000003_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 09:45 /wa/t/m/h/try_it/prt=p2/delta_0000004_0000004_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:44 /wa/t/m/h/try_it/prt=p2/delta_0000004_0000004_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 815 2019-12-12 09:44 /wa/t/m/h/try_it/prt=p2/delta_0000004_0000004_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 10:06 /wa/t/m/h/try_it/prt=p3 drwxrwx---+ - hive hadoop 0 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p3/delete_delta_0000003_0000003_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p3/delete_delta_0000003_0000003_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 727 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p3/delete_delta_0000003_0000003_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 08:15 /wa/t/m/h/try_it/prt=p3/delta_0000002_0000002_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 08:15 /wa/t/m/h/try_it/prt=p3/delta_0000002_0000002_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 796 2019-12-12 08:15 /wa/t/m/h/try_it/prt=p3/delta_0000002_0000002_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p3/delta_0000003_0000003_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p3/delta_0000003_0000003_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 807 2019-12-12 09:34 /wa/t/m/h/try_it/prt=p3/delta_0000003_0000003_0000/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 10:06 /wa/t/m/h/try_it/prt=p3/delta_0000006_0000006_0000 -rw-rw----+ 3 hive hadoop 1 2019-12-12 10:06 /wa/t/m/h/try_it/prt=p3/delta_0000006_0000006_0000/_orc_acid_version -rw-rw----+ 3 hive hadoop 813 2019-12-12 10:06 /wa/t/m/h/try_it/prt=p3/delta_0000006_0000006_0000/bucket_00000 |
As that blog post, and the directory listing above, shows, there where a total of six ACID transactions that have occurred across three partitions to get to this point. The table looks like the following.
select * from try_it; +------------+---------------+---------------+-------------+ | try_it.id | try_it.a_val | try_it.b_val | try_it.prt | +------------+---------------+---------------+-------------+ | 2 | noise | bogus3 | p2 | | 3 | noise | bogus2 | p3 | | 1 | noise | bogus2 | p3 | +------------+---------------+---------------+-------------+ 3 rows selected (0.307 seconds) |
As https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-Compactor shows, we need to make sure hive.compactor.initiator.on is set to true for the compactor to be run.
This type of compaction is scheduled after the number of delta directories passes the value set in the hive.compactor.delta.num.threshold property, but you can also trigger it to run on-demand.
ALTER TABLE try_it COMPACT 'minor'; ERROR : FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. You must specify a partition to compact for partitioned tables |
This error helps us by making the point that we must run compaction on a specific partition unless the table is not partitioned. Let’s try it again and be sure to wait until it completes!
ALTER TABLE try_it partition (prt='p1') COMPACT 'minor'; show compactions; +---------------+-----------+----------+------------+--------+------------+-----------+----------------+---------------+-------------------------+ | compactionid | dbname | tabname | partname | type | state | workerid | starttime | duration | hadoopjobid | +---------------+-----------+----------+------------+--------+------------+-----------+----------------+---------------+-------------------------+ | CompactionId | Database | Table | Partition | Type | State | Worker | Start Time | Duration(ms) | HadoopJobId | | 1 | default | try_it | prt=p1 | MINOR | succeeded | --- | 1576145642000 | 179000 | job_1575915931720_0012 | +---------------+-----------+----------+------------+--------+------------+-----------+----------------+---------------+-------------------------+ 2 rows selected (0.031 seconds) |
Let’s look at the file system again for the p1 partition.
$ hdfs dfs -ls -R /wa/t/m/h/try_it/prt=p1 drwxrwx---+ - hive hadoop 0 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delete_delta_0000001_0000005 -rw-rw----+ 3 hive hadoop 1 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delete_delta_0000001_0000005/_orc_acid_version -rw-rw----+ 3 hive hadoop 654 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delete_delta_0000001_0000005/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000005 -rw-rw----+ 3 hive hadoop 1 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000005/_orc_acid_version -rw-rw----+ 3 hive hadoop 670 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000005/bucket_00000 |
Since there were changes in this partition from transaction #s 1, 3, and 5, we now see rolled together versions of the delta directories spanning these transaction #s. Let’s verify that the contents of the files have the rolled up details in a single file for the delta and delete_delta transactions.
$ hdfs dfs -get /wa/t/m/h/try_it/prt=p1/delete_delta_0000001_0000005/bucket_00000 p1Minor-delete_delta
$ java -jar orc-tools-1.5.1-uber.jar data p1Minor-delete_delta
Processing data file p1Minor-delete_delta [length: 654]
{"operation":2,"originalTransaction":1,"bucket":536870912,"rowId":0,"currentTransaction":3,
"row":null}
{"operation":2,"originalTransaction":3,"bucket":536870912,"rowId":0,"currentTransaction":5,
"row":null}
$ hdfs dfs -get /wa/t/m/h/try_it/prt=p1/delta_0000001_0000005/bucket_00000 p1Minor-delta
$ java -jar orc-tools-1.5.1-uber.jar data p1Minor-delta
Processing data file p1Minor-delta [length: 670]
{"operation":0,"originalTransaction":1,"bucket":536870912,"rowId":0,"currentTransaction":1,
"row":{"id":1,"a_val":"noise","b_val":"bogus"}}
{"operation":0,"originalTransaction":3,"bucket":536870912,"rowId":0,"currentTransaction":3,
"row":{"id":1,"a_val":"noise","b_val":"bogus2"}} |
Even though the minor compacted delete_delta file only shows transaction IDs 3 and 5 (see the currentTransaction attributes) and the delta only includes 1 and 3, both of these compacted files show the comprehensive width of 0000001_0000005.
Now, initiate minor compacting for the the other two partitions.
ALTER TABLE try_it partition (prt='p2') COMPACT 'minor'; ALTER TABLE try_it partition (prt='p3') COMPACT 'minor'; show compactions INFO : Starting task [Stage-0:DDL] in serial mode INFO : Completed executing command(queryId=hive_20191212201440_3a58f8c2-ebc2-4ebe-96e3-a774bf8bec65); Time taken: 0.002 seconds INFO : OK +---------------+-----------+----------+------------+--------+------------+-------------------------------------------------+----------------+---------------+-------------------------+ | compactionid | dbname | tabname | partname | type | state | workerid | starttime | duration | hadoopjobid | +---------------+-----------+----------+------------+--------+------------+-------------------------------------------------+----------------+---------------+-------------------------+ | CompactionId | Database | Table | Partition | Type | State | Worker | Start Time | Duration(ms) | HadoopJobId | | 2 | default | try_it | prt=p2 | MINOR | working | ip-172-30-10-206.us-west-2.compute.internal-37 | 1576181672000 | --- | job_1575915931720_0013 | | 3 | default | try_it | prt=p3 | MINOR | working | ip-172-30-10-206.us-west-2.compute.internal-36 | 1576181677000 | --- | job_1575915931720_0014 | | 1 | default | try_it | prt=p1 | MINOR | succeeded | --- | 1576145642000 | 179000 | job_1575915931720_0012 | +---------------+-----------+----------+------------+--------+------------+-------------------------------------------------+----------------+---------------+-------------------------+ 4 rows selected (0.03 seconds) |
Once those two compacting process finish, the table’s underlying filesystem footprint should look like the following.
$ hdfs dfs -ls -R /wa/t/m/h/try_it drwxrwx---+ - hive hadoop 0 2019-12-12 10:17 /wa/t/m/h/try_it/prt=p1 drwxrwx---+ - hive hadoop 0 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delete_delta_0000001_0000005 -rw-rw----+ 3 hive hadoop 1 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delete_delta_0000001_0000005/_orc_acid_version -rw-rw----+ 3 hive hadoop 654 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delete_delta_0000001_0000005/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000005 -rw-rw----+ 3 hive hadoop 1 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000005/_orc_acid_version -rw-rw----+ 3 hive hadoop 670 2019-12-12 10:16 /wa/t/m/h/try_it/prt=p1/delta_0000001_0000005/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 20:14 /wa/t/m/h/try_it/prt=p2 drwxrwx---+ - hive hadoop 0 2019-12-12 20:14 /wa/t/m/h/try_it/prt=p2/delete_delta_0000002_0000004 -rw-rw----+ 3 hive hadoop 1 2019-12-12 20:14 /wa/t/m/h/try_it/prt=p2/delete_delta_0000002_0000004/_orc_acid_version -rw-rw----+ 3 hive hadoop 654 2019-12-12 20:14 /wa/t/m/h/try_it/prt=p2/delete_delta_0000002_0000004/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 20:14 /wa/t/m/h/try_it/prt=p2/delta_0000002_0000004 -rw-rw----+ 3 hive hadoop 1 2019-12-12 20:14 /wa/t/m/h/try_it/prt=p2/delta_0000002_0000004/_orc_acid_version -rw-rw----+ 3 hive hadoop 670 2019-12-12 20:14 /wa/t/m/h/try_it/prt=p2/delta_0000002_0000004/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 20:15 /wa/t/m/h/try_it/prt=p3 drwxrwx---+ - hive hadoop 0 2019-12-12 20:15 /wa/t/m/h/try_it/prt=p3/delete_delta_0000002_0000006 -rw-rw----+ 3 hive hadoop 1 2019-12-12 20:15 /wa/t/m/h/try_it/prt=p3/delete_delta_0000002_0000006/_orc_acid_version -rw-rw----+ 3 hive hadoop 650 2019-12-12 20:15 /wa/t/m/h/try_it/prt=p3/delete_delta_0000002_0000006/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 20:15 /wa/t/m/h/try_it/prt=p3/delta_0000002_0000006 -rw-rw----+ 3 hive hadoop 1 2019-12-12 20:15 /wa/t/m/h/try_it/prt=p3/delta_0000002_0000006/_orc_acid_version -rw-rw----+ 3 hive hadoop 678 2019-12-12 20:15 /wa/t/m/h/try_it/prt=p3/delta_0000002_0000006/bucket_00000 |
This type of compaction is scheduled based on the value set in the hive.compactor.delta.pct.threshold property whose formal definition expresses it best.
Percentage (fractional) size of the delta files relative to the base that will trigger a major compaction. (1.0 = 100%, so the default 0.1 = 10%.)
And, of course, you can also trigger it to run on-demand as shown below; again, let these processes finish before checking again.
ALTER TABLE try_it partition (prt='p1') COMPACT 'major'; ALTER TABLE try_it partition (prt='p2') COMPACT 'major'; ALTER TABLE try_it partition (prt='p3') COMPACT 'major'; +---------------+-----------+----------+------------+--------+------------+-----------+----------------+---------------+-------------------------+ | compactionid | dbname | tabname | partname | type | state | workerid | starttime | duration | hadoopjobid | +---------------+-----------+----------+------------+--------+------------+-----------+----------------+---------------+-------------------------+ | CompactionId | Database | Table | Partition | Type | State | Worker | Start Time | Duration(ms) | HadoopJobId | | 1 | default | try_it | prt=p1 | MINOR | succeeded | --- | 1576145642000 | 179000 | job_1575915931720_0012 | | 2 | default | try_it | prt=p2 | MINOR | succeeded | --- | 1576181672000 | 22000 | job_1575915931720_0013 | | 3 | default | try_it | prt=p3 | MINOR | succeeded | --- | 1576181677000 | 37000 | job_1575915931720_0014 | | 4 | default | try_it | prt=p1 | MAJOR | succeeded | --- | 1576183603000 | 31000 | job_1575915931720_0015 | | 5 | default | try_it | prt=p2 | MAJOR | succeeded | --- | 1576187575000 | 50000 | job_1575915931720_0017 | | 6 | default | try_it | prt=p3 | MAJOR | succeeded | --- | 1576187583000 | 57000 | job_1575915931720_0018 | +---------------+-----------+----------+------------+--------+------------+-----------+----------------+---------------+-------------------------+ 7 rows selected (0.029 seconds) |
This will build a single “base” file for each partition.
$ hdfs dfs -ls -R /wa/t/m/h/try_it drwxrwx---+ - hive hadoop 0 2019-12-12 20:47 /wa/t/m/h/try_it/prt=p1 drwxrwx---+ - hive hadoop 0 2019-12-12 20:46 /wa/t/m/h/try_it/prt=p1/base_0000005 -rw-rw----+ 3 hive hadoop 48 2019-12-12 20:46 /wa/t/m/h/try_it/prt=p1/base_0000005/_metadata_acid -rw-rw----+ 3 hive hadoop 1 2019-12-12 20:46 /wa/t/m/h/try_it/prt=p1/base_0000005/_orc_acid_version -rw-rw----+ 3 hive hadoop 228 2019-12-12 20:46 /wa/t/m/h/try_it/prt=p1/base_0000005/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p2 drwxrwx---+ - hive hadoop 0 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p2/base_0000004 -rw-rw----+ 3 hive hadoop 48 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p2/base_0000004/_metadata_acid -rw-rw----+ 3 hive hadoop 1 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p2/base_0000004/_orc_acid_version -rw-rw----+ 3 hive hadoop 815 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p2/base_0000004/bucket_00000 drwxrwx---+ - hive hadoop 0 2019-12-12 21:54 /wa/t/m/h/try_it/prt=p3 drwxrwx---+ - hive hadoop 0 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p3/base_0000006 -rw-rw----+ 3 hive hadoop 48 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p3/base_0000006/_metadata_acid -rw-rw----+ 3 hive hadoop 1 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p3/base_0000006/_orc_acid_version -rw-rw----+ 3 hive hadoop 835 2019-12-12 21:53 /wa/t/m/h/try_it/prt=p3/base_0000006/bucket_00000 |
Looking at p1’s data we make sure there is no data for this partition.
$ hdfs dfs -get /wa/t/m/h/try_it/prt=p1/base_0000005/bucket_00000 p1Base $ java -jar orc-tools-1.5.1-uber.jar data p1Base Processing data file p1Base [length: 228] |
We can see that p2 has a single row.
$ hdfs dfs -get /wa/t/m/h/try_it/prt=p2/base_0000004/bucket_00000 p2Base
$ java -jar orc-tools-1.5.1-uber.jar data p2Base
Processing data file p2Base [length: 815]
{"operation":0,"originalTransaction":4,"bucket":536870912,"rowId":0,"currentTransaction":4,
"row":{"id":2,"a_val":"noise","b_val":"bogus3"}} |
And lastly, we verify that p3’s data contains two rows.
$ hdfs dfs -get /wa/t/m/h/try_it/prt=p3/base_0000006/bucket_00000 p3Base
$ java -jar orc-tools-1.5.1-uber.jar data p3Base
Processing data file p3Base [length: 835]
{"operation":0,"originalTransaction":3,"bucket":536870912,"rowId":0,"currentTransaction":3,
"row":{"id":3,"a_val":"noise","b_val":"bogus2"}}
{"operation":0,"originalTransaction":6,"bucket":536870912,"rowId":0,"currentTransaction":6,
"row":{"id":1,"a_val":"noise","b_val":"bogus2"}} |
Again, the contents of the now fully compacted into base files table looks like the following.
select * from try_it; +------------+---------------+---------------+-------------+ | try_it.id | try_it.a_val | try_it.b_val | try_it.prt | +------------+---------------+---------------+-------------+ | 2 | noise | bogus3 | p2 | | 3 | noise | bogus2 | p3 | | 1 | noise | bogus2 | p3 | +------------+---------------+---------------+-------------+ 3 rows selected (0.307 seconds) |