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Version: 0.10.0

CLI

Once hudi has been built, the shell can be fired by via cd hudi-cli && ./hudi-cli.sh. A hudi table resides on DFS, in a location referred to as the basePath and we would need this location in order to connect to a Hudi table. Hudi library effectively manages this table internally, using .hoodie subfolder to track all metadata.

To initialize a hudi table, use the following command.

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* / / / \ \/ / / \ \/ / / \ \__\ *
* / / / \ / / \ / / \/__/ *
* \/__/ \/__/ \/__/ Apache Hudi CLI *
* *
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hudi->create --path /user/hive/warehouse/table1 --tableName hoodie_table_1 --tableType COPY_ON_WRITE
.....

To see the description of hudi table, use the command:

hudi:hoodie_table_1->desc
18/09/06 15:57:19 INFO timeline.HoodieActiveTimeline: Loaded instants []
_________________________________________________________
| Property | Value |
|========================================================|
| basePath | ... |
| metaPath | ... |
| fileSystem | hdfs |
| hoodie.table.name | hoodie_table_1 |
| hoodie.table.type | COPY_ON_WRITE |
| hoodie.archivelog.folder| |

Following is a sample command to connect to a Hudi table contains uber trips.

hudi:trips->connect --path /app/uber/trips

16/10/05 23:20:37 INFO model.HoodieTableMetadata: All commits :HoodieCommits{commitList=[20161002045850, 20161002052915, 20161002055918, 20161002065317, 20161002075932, 20161002082904, 20161002085949, 20161002092936, 20161002105903, 20161002112938, 20161002123005, 20161002133002, 20161002155940, 20161002165924, 20161002172907, 20161002175905, 20161002190016, 20161002192954, 20161002195925, 20161002205935, 20161002215928, 20161002222938, 20161002225915, 20161002232906, 20161003003028, 20161003005958, 20161003012936, 20161003022924, 20161003025859, 20161003032854, 20161003042930, 20161003052911, 20161003055907, 20161003062946, 20161003065927, 20161003075924, 20161003082926, 20161003085925, 20161003092909, 20161003100010, 20161003102913, 20161003105850, 20161003112910, 20161003115851, 20161003122929, 20161003132931, 20161003142952, 20161003145856, 20161003152953, 20161003155912, 20161003162922, 20161003165852, 20161003172923, 20161003175923, 20161003195931, 20161003210118, 20161003212919, 20161003215928, 20161003223000, 20161003225858, 20161004003042, 20161004011345, 20161004015235, 20161004022234, 20161004063001, 20161004072402, 20161004074436, 20161004080224, 20161004082928, 20161004085857, 20161004105922, 20161004122927, 20161004142929, 20161004163026, 20161004175925, 20161004194411, 20161004203202, 20161004211210, 20161004214115, 20161004220437, 20161004223020, 20161004225321, 20161004231431, 20161004233643, 20161005010227, 20161005015927, 20161005022911, 20161005032958, 20161005035939, 20161005052904, 20161005070028, 20161005074429, 20161005081318, 20161005083455, 20161005085921, 20161005092901, 20161005095936, 20161005120158, 20161005123418, 20161005125911, 20161005133107, 20161005155908, 20161005163517, 20161005165855, 20161005180127, 20161005184226, 20161005191051, 20161005193234, 20161005203112, 20161005205920, 20161005212949, 20161005223034, 20161005225920]}
Metadata for table trips loaded

Once connected to the table, a lot of other commands become available. The shell has contextual autocomplete help (press TAB) and below is a list of all commands, few of which are reviewed in this section are reviewed

hudi:trips->help
* ! - Allows execution of operating system (OS) commands
* // - Inline comment markers (start of line only)
* ; - Inline comment markers (start of line only)
* addpartitionmeta - Add partition metadata to a table, if not present
* clear - Clears the console
* cls - Clears the console
* commit rollback - Rollback a commit
* commits compare - Compare commits with another Hoodie table
* commit showfiles - Show file level details of a commit
* commit showpartitions - Show partition level details of a commit
* commits refresh - Refresh the commits
* commits show - Show the commits
* commits sync - Compare commits with another Hoodie table
* connect - Connect to a hoodie table
* date - Displays the local date and time
* exit - Exits the shell
* help - List all commands usage
* quit - Exits the shell
* records deduplicate - De-duplicate a partition path contains duplicates & produce repaired files to replace with
* script - Parses the specified resource file and executes its commands
* stats filesizes - File Sizes. Display summary stats on sizes of files
* stats wa - Write Amplification. Ratio of how many records were upserted to how many records were actually written
* sync validate - Validate the sync by counting the number of records
* system properties - Shows the shell's properties
* utils loadClass - Load a class
* version - Displays shell version

hudi:trips->

Inspecting Commits

The task of upserting or inserting a batch of incoming records is known as a commit in Hudi. A commit provides basic atomicity guarantees such that only committed data is available for querying. Each commit has a monotonically increasing string/number called the commit number. Typically, this is the time at which we started the commit.

To view some basic information about the last 10 commits,

hudi:trips->commits show --sortBy "Total Bytes Written" --desc true --limit 10
________________________________________________________________________________________________________________________________________________________________________
| CommitTime | Total Bytes Written| Total Files Added| Total Files Updated| Total Partitions Written| Total Records Written| Total Update Records Written| Total Errors|
|=======================================================================================================================================================================|
....
....
....

At the start of each write, Hudi also writes a .inflight commit to the .hoodie folder. You can use the timestamp there to estimate how long the commit has been inflight

$ hdfs dfs -ls /app/uber/trips/.hoodie/*.inflight
-rw-r--r-- 3 vinoth supergroup 321984 2016-10-05 23:18 /app/uber/trips/.hoodie/20161005225920.inflight

Drilling Down to a specific Commit

To understand how the writes spread across specific partiions,

hudi:trips->commit showpartitions --commit 20161005165855 --sortBy "Total Bytes Written" --desc true --limit 10
__________________________________________________________________________________________________________________________________________
| Partition Path| Total Files Added| Total Files Updated| Total Records Inserted| Total Records Updated| Total Bytes Written| Total Errors|
|=========================================================================================================================================|
....
....

If you need file level granularity , we can do the following

hudi:trips->commit showfiles --commit 20161005165855 --sortBy "Partition Path"
________________________________________________________________________________________________________________________________________________________
| Partition Path| File ID | Previous Commit| Total Records Updated| Total Records Written| Total Bytes Written| Total Errors|
|=======================================================================================================================================================|
....
....

FileSystem View

Hudi views each partition as a collection of file-groups with each file-group containing a list of file-slices in commit order (See concepts). The below commands allow users to view the file-slices for a data-set.

hudi:stock_ticks_mor->show fsview all
....
_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
| Partition | FileId | Base-Instant | Data-File | Data-File Size| Num Delta Files| Total Delta File Size| Delta Files |
|==============================================================================================================================================================================================================================================================================================================================================================================================================|
| 2018/08/31| 111415c3-f26d-4639-86c8-f9956f245ac3| 20181002180759| hdfs://namenode:8020/user/hive/warehouse/stock_ticks_mor/2018/08/31/111415c3-f26d-4639-86c8-f9956f245ac3_0_20181002180759.parquet| 432.5 KB | 1 | 20.8 KB | [HoodieLogFile {hdfs://namenode:8020/user/hive/warehouse/stock_ticks_mor/2018/08/31/.111415c3-f26d-4639-86c8-f9956f245ac3_20181002180759.log.1}]|



hudi:stock_ticks_mor->show fsview latest --partitionPath "2018/08/31"
......
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
| Partition | FileId | Base-Instant | Data-File | Data-File Size| Num Delta Files| Total Delta Size| Delta Size - compaction scheduled| Delta Size - compaction unscheduled| Delta To Base Ratio - compaction scheduled| Delta To Base Ratio - compaction unscheduled| Delta Files - compaction scheduled | Delta Files - compaction unscheduled|
|=================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================|
| 2018/08/31| 111415c3-f26d-4639-86c8-f9956f245ac3| 20181002180759| hdfs://namenode:8020/user/hive/warehouse/stock_ticks_mor/2018/08/31/111415c3-f26d-4639-86c8-f9956f245ac3_0_20181002180759.parquet| 432.5 KB | 1 | 20.8 KB | 20.8 KB | 0.0 B | 0.0 B | 0.0 B | [HoodieLogFile {hdfs://namenode:8020/user/hive/warehouse/stock_ticks_mor/2018/08/31/.111415c3-f26d-4639-86c8-f9956f245ac3_20181002180759.log.1}]| [] |

Statistics

Since Hudi directly manages file sizes for DFS table, it might be good to get an overall picture

hudi:trips->stats filesizes --partitionPath 2016/09/01 --sortBy "95th" --desc true --limit 10
________________________________________________________________________________________________
| CommitTime | Min | 10th | 50th | avg | 95th | Max | NumFiles| StdDev |
|===============================================================================================|
| <COMMIT_ID> | 93.9 MB | 93.9 MB | 93.9 MB | 93.9 MB | 93.9 MB | 93.9 MB | 2 | 2.3 KB |
....
....

In case of Hudi write taking much longer, it might be good to see the write amplification for any sudden increases

hudi:trips->stats wa
__________________________________________________________________________
| CommitTime | Total Upserted| Total Written| Write Amplifiation Factor|
|=========================================================================|
....
....

Archived Commits

In order to limit the amount of growth of .commit files on DFS, Hudi archives older .commit files (with due respect to the cleaner policy) into a commits.archived file. This is a sequence file that contains a mapping from commitNumber => json with raw information about the commit (same that is nicely rolled up above).

Compactions

To get an idea of the lag between compaction and writer applications, use the below command to list down all pending compactions.

hudi:trips->compactions show all
___________________________________________________________________
| Compaction Instant Time| State | Total FileIds to be Compacted|
|==================================================================|
| <INSTANT_1> | REQUESTED| 35 |
| <INSTANT_2> | INFLIGHT | 27 |

To inspect a specific compaction plan, use

hudi:trips->compaction show --instant <INSTANT_1>
_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
| Partition Path| File Id | Base Instant | Data File Path | Total Delta Files| getMetrics |
|================================================================================================================================================================================================================================================
| 2018/07/17 | <UUID> | <INSTANT_1> | viewfs://ns-default/.../../UUID_<INSTANT>.parquet | 1 | {TOTAL_LOG_FILES=1.0, TOTAL_IO_READ_MB=1230.0, TOTAL_LOG_FILES_SIZE=2.51255751E8, TOTAL_IO_WRITE_MB=991.0, TOTAL_IO_MB=2221.0}|

To manually schedule or run a compaction, use the below command. This command uses spark launcher to perform compaction operations.

NOTE: Make sure no other application is scheduling compaction for this table concurrently {: .notice--info}

hudi:trips->help compaction schedule
Keyword: compaction schedule
Description: Schedule Compaction
Keyword: sparkMemory
Help: Spark executor memory
Mandatory: false
Default if specified: '__NULL__'
Default if unspecified: '1G'

* compaction schedule - Schedule Compaction
hudi:trips->help compaction run
Keyword: compaction run
Description: Run Compaction for given instant time
Keyword: tableName
Help: Table name
Mandatory: true
Default if specified: '__NULL__'
Default if unspecified: '__NULL__'

Keyword: parallelism
Help: Parallelism for hoodie compaction
Mandatory: true
Default if specified: '__NULL__'
Default if unspecified: '__NULL__'

Keyword: schemaFilePath
Help: Path for Avro schema file
Mandatory: true
Default if specified: '__NULL__'
Default if unspecified: '__NULL__'

Keyword: sparkMemory
Help: Spark executor memory
Mandatory: true
Default if specified: '__NULL__'
Default if unspecified: '__NULL__'

Keyword: retry
Help: Number of retries
Mandatory: true
Default if specified: '__NULL__'
Default if unspecified: '__NULL__'

Keyword: compactionInstant
Help: Base path for the target hoodie table
Mandatory: true
Default if specified: '__NULL__'
Default if unspecified: '__NULL__'

* compaction run - Run Compaction for given instant time

Validate Compaction

Validating a compaction plan : Check if all the files necessary for compactions are present and are valid

hudi:stock_ticks_mor->compaction validate --instant 20181005222611
...

COMPACTION PLAN VALID

___________________________________________________________________________________________________________________________________________________________________________________________________________________________
| File Id | Base Instant Time| Base Data File | Num Delta Files| Valid| Error|
|==========================================================================================================================================================================================================================|
| 05320e98-9a57-4c38-b809-a6beaaeb36bd| 20181005222445 | hdfs://namenode:8020/user/hive/warehouse/stock_ticks_mor/2018/08/31/05320e98-9a57-4c38-b809-a6beaaeb36bd_0_20181005222445.parquet| 1 | true | |



hudi:stock_ticks_mor->compaction validate --instant 20181005222601

COMPACTION PLAN INVALID

_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
| File Id | Base Instant Time| Base Data File | Num Delta Files| Valid| Error |
|=====================================================================================================================================================================================================================================================================================================|
| 05320e98-9a57-4c38-b809-a6beaaeb36bd| 20181005222445 | hdfs://namenode:8020/user/hive/warehouse/stock_ticks_mor/2018/08/31/05320e98-9a57-4c38-b809-a6beaaeb36bd_0_20181005222445.parquet| 1 | false| All log files specified in compaction operation is not present. Missing .... |

NOTE: The following commands must be executed without any other writer/ingestion application running. {: .notice--warning}

Sometimes, it becomes necessary to remove a fileId from a compaction-plan inorder to speed-up or unblock compaction operation. Any new log-files that happened on this file after the compaction got scheduled will be safely renamed so that are preserved. Hudi provides the following CLI to support it

Unscheduling Compaction

hudi:trips->compaction unscheduleFileId --fileId <FileUUID>
....
No File renames needed to unschedule file from pending compaction. Operation successful.

In other cases, an entire compaction plan needs to be reverted. This is supported by the following CLI

hudi:trips->compaction unschedule --compactionInstant <compactionInstant>
.....
No File renames needed to unschedule pending compaction. Operation successful.

Repair Compaction

The above compaction unscheduling operations could sometimes fail partially (e:g -> DFS temporarily unavailable). With partial failures, the compaction operation could become inconsistent with the state of file-slices. When you run compaction validate, you can notice invalid compaction operations if there is one. In these cases, the repair command comes to the rescue, it will rearrange the file-slices so that there is no loss and the file-slices are consistent with the compaction plan

hudi:stock_ticks_mor->compaction repair --instant 20181005222611
......
Compaction successfully repaired
.....