[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
[ https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13808548#comment-13808548 ] Roshan Naik commented on HIVE-4196: --- Moving the streaming work to a new jira HIVE-5687 since it will be based on a different design. Support for Streaming Partitions in Hive Key: HIVE-4196 URL: https://issues.apache.org/jira/browse/HIVE-4196 Project: Hive Issue Type: New Feature Components: Database/Schema, HCatalog Affects Versions: 0.10.1 Reporter: Roshan Naik Assignee: Roshan Naik Attachments: HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.docx, HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.pdf, HIVE-4196.v1.patch Motivation: Allow Hive users to immediately query data streaming in through clients such as Flume. Currently Hive partitions must be created after all the data for the partition is available. Thereafter, data in the partitions is considered immutable. This proposal introduces the notion of a streaming partition into which new files an be committed periodically and made available for queries before the partition is closed and converted into a standard partition. The admin enables streaming partition on a table using DDL. He provides the following pieces of information: - Name of the partition in the table on which streaming is enabled - Frequency at which the streaming partition should be closed and converted into a standard partition. Tables with streaming partition enabled will be partitioned by one and only one column. It is assumed that this column will contain a timestamp. Closing the current streaming partition converts it into a standard partition. Based on the specified frequency, the current streaming partition is closed and a new one created for future writes. This is referred to as 'rolling the partition'. A streaming partition's life cycle is as follows: - A new streaming partition is instantiated for writes - Streaming clients request (via webhcat) for a HDFS file name into which they can write a chunk of records for a specific table. - Streaming clients write a chunk (via webhdfs) to that file and commit it(via webhcat). Committing merely indicates that the chunk has been written completely and ready for serving queries. - When the partition is rolled, all committed chunks are swept into single directory and a standard partition pointing to that directory is created. The streaming partition is closed and new streaming partition is created. Rolling the partition is atomic. Streaming clients are agnostic of partition rolling. - Hive queries will be able to query the partition that is currently open for streaming. only committed chunks will be visible. read consistency will be ensured so that repeated reads of the same partition will be idempotent for the lifespan of the query. Partition rolling requires an active agent/thread running to check when it is time to roll and trigger the roll. This could be either be achieved by using an external agent such as Oozie (preferably) or an internal agent. -- This message was sent by Atlassian JIRA (v6.1#6144)
[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
[ https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13776952#comment-13776952 ] Roshan Naik commented on HIVE-4196: --- Thanks Ashutosh. Since your recommendations apply to subtask HIVE-5138, I have copied ur comments over to it. I will address them there. Support for Streaming Partitions in Hive Key: HIVE-4196 URL: https://issues.apache.org/jira/browse/HIVE-4196 Project: Hive Issue Type: New Feature Components: Database/Schema, HCatalog Affects Versions: 0.10.1 Reporter: Roshan Naik Assignee: Roshan Naik Attachments: HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.docx, HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.pdf, HIVE-4196.v1.patch Motivation: Allow Hive users to immediately query data streaming in through clients such as Flume. Currently Hive partitions must be created after all the data for the partition is available. Thereafter, data in the partitions is considered immutable. This proposal introduces the notion of a streaming partition into which new files an be committed periodically and made available for queries before the partition is closed and converted into a standard partition. The admin enables streaming partition on a table using DDL. He provides the following pieces of information: - Name of the partition in the table on which streaming is enabled - Frequency at which the streaming partition should be closed and converted into a standard partition. Tables with streaming partition enabled will be partitioned by one and only one column. It is assumed that this column will contain a timestamp. Closing the current streaming partition converts it into a standard partition. Based on the specified frequency, the current streaming partition is closed and a new one created for future writes. This is referred to as 'rolling the partition'. A streaming partition's life cycle is as follows: - A new streaming partition is instantiated for writes - Streaming clients request (via webhcat) for a HDFS file name into which they can write a chunk of records for a specific table. - Streaming clients write a chunk (via webhdfs) to that file and commit it(via webhcat). Committing merely indicates that the chunk has been written completely and ready for serving queries. - When the partition is rolled, all committed chunks are swept into single directory and a standard partition pointing to that directory is created. The streaming partition is closed and new streaming partition is created. Rolling the partition is atomic. Streaming clients are agnostic of partition rolling. - Hive queries will be able to query the partition that is currently open for streaming. only committed chunks will be visible. read consistency will be ensured so that repeated reads of the same partition will be idempotent for the lifespan of the query. Partition rolling requires an active agent/thread running to check when it is time to roll and trigger the roll. This could be either be achieved by using an external agent such as Oozie (preferably) or an internal agent. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
[ https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13770314#comment-13770314 ] Ashutosh Chauhan commented on HIVE-4196: Few high level comments: * We should try to eliminate the need of intermediate staging area while rolling on new partitions. Seems like there should not be any gotchas while moving data from streaming dir to partition dir directly. * We should make thrift apis in metastore forward compatible. One way to do that is to use struct (which contains all parameters) instead of passing in list of arguments. * We should try to leave TBLS table untouched in backend db. That will simplify upgrade story. One way to do that is to have all new columns in a new table and than add constraints for this new table. Support for Streaming Partitions in Hive Key: HIVE-4196 URL: https://issues.apache.org/jira/browse/HIVE-4196 Project: Hive Issue Type: New Feature Components: Database/Schema, HCatalog Affects Versions: 0.10.1 Reporter: Roshan Naik Assignee: Roshan Naik Attachments: HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.docx, HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.pdf, HIVE-4196.v1.patch Motivation: Allow Hive users to immediately query data streaming in through clients such as Flume. Currently Hive partitions must be created after all the data for the partition is available. Thereafter, data in the partitions is considered immutable. This proposal introduces the notion of a streaming partition into which new files an be committed periodically and made available for queries before the partition is closed and converted into a standard partition. The admin enables streaming partition on a table using DDL. He provides the following pieces of information: - Name of the partition in the table on which streaming is enabled - Frequency at which the streaming partition should be closed and converted into a standard partition. Tables with streaming partition enabled will be partitioned by one and only one column. It is assumed that this column will contain a timestamp. Closing the current streaming partition converts it into a standard partition. Based on the specified frequency, the current streaming partition is closed and a new one created for future writes. This is referred to as 'rolling the partition'. A streaming partition's life cycle is as follows: - A new streaming partition is instantiated for writes - Streaming clients request (via webhcat) for a HDFS file name into which they can write a chunk of records for a specific table. - Streaming clients write a chunk (via webhdfs) to that file and commit it(via webhcat). Committing merely indicates that the chunk has been written completely and ready for serving queries. - When the partition is rolled, all committed chunks are swept into single directory and a standard partition pointing to that directory is created. The streaming partition is closed and new streaming partition is created. Rolling the partition is atomic. Streaming clients are agnostic of partition rolling. - Hive queries will be able to query the partition that is currently open for streaming. only committed chunks will be visible. read consistency will be ensured so that repeated reads of the same partition will be idempotent for the lifespan of the query. Partition rolling requires an active agent/thread running to check when it is time to roll and trigger the roll. This could be either be achieved by using an external agent such as Oozie (preferably) or an internal agent. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
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https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13752946#comment-13752946
]
Roshan Naik commented on HIVE-4196:
---
{quote} According to the Hive coding conventions lines should be bounded at
100 characters. Many lines in this patch exceed that. {quote}
Will fix the ones which are not in the thrift generated files.
{quote} I'm surprised to see that streamingStatus sets the chunk id for the
table. {quote}
Seems like a bug. Will fix.
{quote} The logic at the end of of these functions doesn't look right. Take
getNextChunkID for example. If commitTransaction fails (line 2132) rollback
will be called but the next chunk id will still be returned. It seems you need
a check on success after commit. I realize many of the calls in the class
follow this, but it doesn't seem right. {quote}
Good catch. At the time I thought commitTxn() will only fail with an exception
does not return false. But on closer inspection there is indeed a corner case
(if rollBack was called) that it returns false also. Its a bizzare thing for a
function to fail with without exceptions. But for now I will fix my code to
live with it.
{quote} In HiveMetaStoreClient.java, is assert what you want? Are you ok with
the validity of the arguments not being checked most of the time?{quote}
Not all checks are in place. There is some checks that will happen at lower
layers. Some at higher. Will be adding more checks.
{quote} I'm trying to figure out whether the chunk files are moved, deleted, or
left alone during the partition rolling. {quote}
That would depend on whether the table is defined to be an external or internal
table. It is essentially an add_partition of the new partition. It calls
HiveMetastore.add_partition_core_notxn() inside a transaction.
Support for Streaming Partitions in Hive
Key: HIVE-4196
URL: https://issues.apache.org/jira/browse/HIVE-4196
Project: Hive
Issue Type: New Feature
Components: Database/Schema, HCatalog
Affects Versions: 0.10.1
Reporter: Roshan Naik
Assignee: Roshan Naik
Attachments: HCatalogStreamingIngestFunctionalSpecificationandDesign-
apr 29- patch1.docx, HCatalogStreamingIngestFunctionalSpecificationandDesign-
apr 29- patch1.pdf, HIVE-4196.v1.patch
Motivation: Allow Hive users to immediately query data streaming in through
clients such as Flume.
Currently Hive partitions must be created after all the data for the
partition is available. Thereafter, data in the partitions is considered
immutable.
This proposal introduces the notion of a streaming partition into which new
files an be committed periodically and made available for queries before the
partition is closed and converted into a standard partition.
The admin enables streaming partition on a table using DDL. He provides the
following pieces of information:
- Name of the partition in the table on which streaming is enabled
- Frequency at which the streaming partition should be closed and converted
into a standard partition.
Tables with streaming partition enabled will be partitioned by one and only
one column. It is assumed that this column will contain a timestamp.
Closing the current streaming partition converts it into a standard
partition. Based on the specified frequency, the current streaming partition
is closed and a new one created for future writes. This is referred to as
'rolling the partition'.
A streaming partition's life cycle is as follows:
- A new streaming partition is instantiated for writes
- Streaming clients request (via webhcat) for a HDFS file name into which
they can write a chunk of records for a specific table.
- Streaming clients write a chunk (via webhdfs) to that file and commit
it(via webhcat). Committing merely indicates that the chunk has been written
completely and ready for serving queries.
- When the partition is rolled, all committed chunks are swept into single
directory and a standard partition pointing to that directory is created. The
streaming partition is closed and new streaming partition is created. Rolling
the partition is atomic. Streaming clients are agnostic of partition rolling.
- Hive queries will be able to query the partition that is currently open
for streaming. only committed chunks will be visible. read consistency will
be ensured so that repeated reads of the same partition will be idempotent
for the lifespan of the query.
Partition rolling requires an active agent/thread running to check when it is
time to roll and trigger the roll. This could be either be achieved by using
an external agent such as Oozie (preferably) or an internal agent.
--
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If you think
[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
[ https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13714235#comment-13714235 ] Alan Gates commented on HIVE-4196: -- Some comments: According to the Hive coding conventions lines should be bounded at 100 characters. Many lines in this patch exceed that. In ObjectStore.java: * I'm surprised to see that streamingStatus sets the chunk id for the table. This seems to be a status call. Why should it be setting chunk id? * The logic at the end of of these functions doesn't look right. Take getNextChunkID for example. If commitTransaction fails (line 2132) rollback will be called but the next chunk id will still be returned. It seems you need a check on success after commit. I realize many of the calls in the class follow this, but it doesn't seem right. In HiveMetaStoreClient.java, is assert what you want? Are you ok with the validity of the arguments not being checked most of the time? I'm trying to figure out whether the chunk files are moved, deleted, or left alone during the partition rolling. From examining the code and playing with Hive it looks like the files will be left alone. But have you tested this? Which leads to, I don't see any tests in this patch. This code needs a lot of tests. Support for Streaming Partitions in Hive Key: HIVE-4196 URL: https://issues.apache.org/jira/browse/HIVE-4196 Project: Hive Issue Type: New Feature Components: Database/Schema, HCatalog Affects Versions: 0.10.1 Reporter: Roshan Naik Assignee: Roshan Naik Attachments: HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.docx, HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.pdf, HIVE-4196.v1.patch Motivation: Allow Hive users to immediately query data streaming in through clients such as Flume. Currently Hive partitions must be created after all the data for the partition is available. Thereafter, data in the partitions is considered immutable. This proposal introduces the notion of a streaming partition into which new files an be committed periodically and made available for queries before the partition is closed and converted into a standard partition. The admin enables streaming partition on a table using DDL. He provides the following pieces of information: - Name of the partition in the table on which streaming is enabled - Frequency at which the streaming partition should be closed and converted into a standard partition. Tables with streaming partition enabled will be partitioned by one and only one column. It is assumed that this column will contain a timestamp. Closing the current streaming partition converts it into a standard partition. Based on the specified frequency, the current streaming partition is closed and a new one created for future writes. This is referred to as 'rolling the partition'. A streaming partition's life cycle is as follows: - A new streaming partition is instantiated for writes - Streaming clients request (via webhcat) for a HDFS file name into which they can write a chunk of records for a specific table. - Streaming clients write a chunk (via webhdfs) to that file and commit it(via webhcat). Committing merely indicates that the chunk has been written completely and ready for serving queries. - When the partition is rolled, all committed chunks are swept into single directory and a standard partition pointing to that directory is created. The streaming partition is closed and new streaming partition is created. Rolling the partition is atomic. Streaming clients are agnostic of partition rolling. - Hive queries will be able to query the partition that is currently open for streaming. only committed chunks will be visible. read consistency will be ensured so that repeated reads of the same partition will be idempotent for the lifespan of the query. Partition rolling requires an active agent/thread running to check when it is time to roll and trigger the roll. This could be either be achieved by using an external agent such as Oozie (preferably) or an internal agent. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
[ https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13669853#comment-13669853 ] Alan Gates commented on HIVE-4196: -- Roshan, Could you post a pdf version of the doc so users without MS Word can read it? Also, could you post a version of the patch without the thrift generated code (anything under src/gen or src-gen) so it's easier for the reviewers to determine what to review? Support for Streaming Partitions in Hive Key: HIVE-4196 URL: https://issues.apache.org/jira/browse/HIVE-4196 Project: Hive Issue Type: New Feature Components: Database/Schema, HCatalog Affects Versions: 0.10.1 Reporter: Roshan Naik Assignee: Roshan Naik Attachments: HCatalogStreamingIngestFunctionalSpecificationandDesign- apr 29- patch1.docx, HIVE-4196.v1.patch Motivation: Allow Hive users to immediately query data streaming in through clients such as Flume. Currently Hive partitions must be created after all the data for the partition is available. Thereafter, data in the partitions is considered immutable. This proposal introduces the notion of a streaming partition into which new files an be committed periodically and made available for queries before the partition is closed and converted into a standard partition. The admin enables streaming partition on a table using DDL. He provides the following pieces of information: - Name of the partition in the table on which streaming is enabled - Frequency at which the streaming partition should be closed and converted into a standard partition. Tables with streaming partition enabled will be partitioned by one and only one column. It is assumed that this column will contain a timestamp. Closing the current streaming partition converts it into a standard partition. Based on the specified frequency, the current streaming partition is closed and a new one created for future writes. This is referred to as 'rolling the partition'. A streaming partition's life cycle is as follows: - A new streaming partition is instantiated for writes - Streaming clients request (via webhcat) for a HDFS file name into which they can write a chunk of records for a specific table. - Streaming clients write a chunk (via webhdfs) to that file and commit it(via webhcat). Committing merely indicates that the chunk has been written completely and ready for serving queries. - When the partition is rolled, all committed chunks are swept into single directory and a standard partition pointing to that directory is created. The streaming partition is closed and new streaming partition is created. Rolling the partition is atomic. Streaming clients are agnostic of partition rolling. - Hive queries will be able to query the partition that is currently open for streaming. only committed chunks will be visible. read consistency will be ensured so that repeated reads of the same partition will be idempotent for the lifespan of the query. Partition rolling requires an active agent/thread running to check when it is time to roll and trigger the roll. This could be either be achieved by using an external agent such as Oozie (preferably) or an internal agent. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
[ https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13608800#comment-13608800 ] eric baldeschwieler commented on HIVE-4196: --- Maybe we should just return both? Support for Streaming Partitions in Hive Key: HIVE-4196 URL: https://issues.apache.org/jira/browse/HIVE-4196 Project: Hive Issue Type: New Feature Components: Database/Schema, HCatalog Affects Versions: 0.10.1 Reporter: Roshan Naik Assignee: Roshan Naik Motivation: Allow Hive users to immediately query data streaming in through clients such as Flume. Currently Hive partitions must be created after all the data for the partition is available. Thereafter, data in the partitions is considered immutable. This proposal introduces the notion of a streaming partition into which new files an be committed periodically and made available for queries before the partition is closed and converted into a standard partition. The admin enables streaming partition on a table using DDL. He provides the following pieces of information: - Name of the partition in the table on which streaming is enabled - Frequency at which the streaming partition should be closed and converted into a standard partition. Tables with streaming partition enabled will be partitioned by one and only one column. It is assumed that this column will contain a timestamp. Closing the current streaming partition converts it into a standard partition. Based on the specified frequency, the current streaming partition is closed and a new one created for future writes. This is referred to as 'rolling the partition'. A streaming partition's life cycle is as follows: - A new streaming partition is instantiated for writes - Streaming clients request (via webhcat) for a HDFS file name into which they can write a chunk of records for a specific table. - Streaming clients write a chunk (via webhdfs) to that file and commit it(via webhcat). Committing merely indicates that the chunk has been written completely and ready for serving queries. - When the partition is rolled, all committed chunks are swept into single directory and a standard partition pointing to that directory is created. The streaming partition is closed and new streaming partition is created. Rolling the partition is atomic. Streaming clients are agnostic of partition rolling. - Hive queries will be able to query the partition that is currently open for streaming. only committed chunks will be visible. read consistency will be ensured so that repeated reads of the same partition will be idempotent for the lifespan of the query. Partition rolling requires an active agent/thread running to check when it is time to roll and trigger the roll. This could be either be achieved by using an external agent such as Oozie (preferably) or an internal agent. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-4196) Support for Streaming Partitions in Hive
[ https://issues.apache.org/jira/browse/HIVE-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13606960#comment-13606960 ] Brock Noland commented on HIVE-4196: Hi Roshan, Looks like a good proposal and a great place for Flume to integrate with Hive! In the proposal how come we have the clients using webhdfs to write a chunk of data? Couldn't the client user any HDFS api? Brock Support for Streaming Partitions in Hive Key: HIVE-4196 URL: https://issues.apache.org/jira/browse/HIVE-4196 Project: Hive Issue Type: New Feature Components: Database/Schema, HCatalog Affects Versions: 0.10.1 Reporter: Roshan Naik Assignee: Roshan Naik Motivation: Allow Hive users to immediately query data streaming in through clients such as Flume. Currently Hive partitions must be created after all the data for the partition is available. Thereafter, data in the partitions is considered immutable. This proposal introduces the notion of a streaming partition into which new files an be committed periodically and made available for queries before the partition is closed and converted into a standard partition. The admin enables streaming partition on a table using DDL. He provides the following pieces of information: - Name of the partition in the table on which streaming is enabled - Frequency at which the streaming partition should be closed and converted into a standard partition. Tables with streaming partition enabled will be partitioned by one and only one column. It is assumed that this column will contain a timestamp. Closing the current streaming partition converts it into a standard partition. Based on the specified frequency, the current streaming partition is closed and a new one created for future writes. This is referred to as 'rolling the partition'. A streaming partition's life cycle is as follows: - A new streaming partition is instantiated for writes - Streaming clients request (via webhcat) for a HDFS file name into which they can write a chunk of records for a specific table. - Streaming clients write a chunk (via webhdfs) to that file and commit it(via webhcat). Committing merely indicates that the chunk has been written completely and ready for serving queries. - When the partition is rolled, all committed chunks are swept into single directory and a standard partition pointing to that directory is created. The streaming partition is closed and new streaming partition is created. Rolling the partition is atomic. Streaming clients are agnostic of partition rolling. - Hive queries will be able to query the partition that is currently open for streaming. only committed chunks will be visible. read consistency will be ensured so that repeated reads of the same partition will be idempotent for the lifespan of the query. Partition rolling requires an active agent/thread running to check when it is time to roll and trigger the roll. This could be either be achieved by using an external agent such as Oozie (preferably) or an internal agent. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
