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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-48) [hbase] Bulk load and dump tools
Date Sat, 26 Jul 2008 22:20:31 GMT

    [ https://issues.apache.org/jira/browse/HBASE-48?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12617222#action_12617222
] 

stack commented on HBASE-48:
----------------------------

Thinking more on this issue, in particular on Billy's suggestion above ('Billy Pearson - 06/Feb/08
01:07 PM'), bulk uploading by writing store files ain't hard:

For a new table (as per Bryan above), its particularly easy.  Do something like:

+ Create table in hbase
+ Mark it read-only or disabled even.
+ Start mapreduce job.  In its configuration would go to the master to read the table description.
+ Map reads whatever the input using whatever formatter and ouputs from the map using HStoreKey
for key and cell content for value.
+ Job would use fancy new TableFileReduce.  Each reducer would write a region.  It'd know
what for start and end keys -- they'd be the first and last it'd see.  Could output these
somewhere so a tail task could find them.  The file outputter would need to also do sequenceids
of some form.
+ When job was done, tail task would insert regions into meta using MetaUtils.
+ Enable the table.
+ If regions are lop-sided, hbase will do the fixup.

If table already exists:

+ Mark table read-only (ensure this prevents splits and that it means memcache is flushed)
+ Start a mapreduce job that read from master the table schema and its regions (and the master's
current time so we don't write records older).
+ Map as above.
+ Reducer as above only insert smarter partitioner, one that respected region boundaries and
that made a reducer per current region.
+ Enable hbase and let it fix up where storefiles written were too big by splitting etc.

It don't seem hard at all to do.

> [hbase] Bulk load and dump tools
> --------------------------------
>
>                 Key: HBASE-48
>                 URL: https://issues.apache.org/jira/browse/HBASE-48
>             Project: Hadoop HBase
>          Issue Type: New Feature
>            Reporter: stack
>            Priority: Minor
>
> Hbase needs tools to facilitate bulk upload and possibly dumping.  Going via the current
APIs, particularly if the dataset is large and cell content is small, uploads can take a long
time even when using many concurrent clients.
> PNUTS folks talked of need for a different API to manage bulk upload/dump.
> Another notion would be to somehow have the bulk loader tools somehow write regions directly
in hdfs.

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