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https://issues.apache.org/jira/browse/HBASE-13260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14365258#comment-14365258
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stack commented on HBASE-13260:
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For consideration, lets say we have a master-private table to host assignment
transitions -- we'd write this internal table rather than update hbase:meta --
and say we have a 1M regions and we are starting up the cluster. Let us say
there are 4 transitions getting a region on line: OFFLINE, OPENING, OPENING,
OPEN, done (after updating hbase:meta). So we'll need to do 4 million writes of
at least a region name + its transition state -- lets call the serialization
128 bytes give or take (we could record just regionid....to cut it down -- in a
short amount of time; about half a gigabyte of data.
Would be worthwhile putting up a test on a single region to see how it does
with a load like this, how many hfiles, what compactions are like.
> Bootstrap Tables for fun and profit
> ------------------------------------
>
> Key: HBASE-13260
> URL: https://issues.apache.org/jira/browse/HBASE-13260
> Project: HBase
> Issue Type: Bug
> Reporter: Enis Soztutar
> Assignee: Enis Soztutar
> Fix For: 2.0.0, 1.1.0
>
> Attachments: hbase-13260_prototype.patch
>
>
> Over at the ProcV2 discussions(HBASE-12439) and elsewhere I was mentioning an
> idea where we may want to use regular old regions to store/persist some data
> needed for HBase master to operate.
> We regularly use system tables for storing system data. acl, meta, namespace,
> quota are some examples. We also store the table state in meta now. Some data
> is persisted in zk only (replication peers and replication state, etc). We
> are moving away from zk as a permanent storage. As any self-respecting
> database does, we should store almost all of our data in HBase itself.
> However, we have an "availability" dependency between different kinds of
> data. For example all system tables need meta to be assigned first. All
> master operations need ns table to be assigned, etc.
> For at least two types of data, (1) procedure v2 states, (2) RS groups in
> HBASE-6721 we cannot depend on meta being assigned since "assignment" itself
> will depend on accessing this data. The solution in (1) is to implement a
> custom WAL format, and custom recover lease and WAL recovery. The solution in
> (2) is to have the table to store this data, but also cache it in zk for
> bootrapping initial assignments.
> For solving both of the above (and possible future use cases if any), I
> propose we add a "boostrap table" concept, which is:
> - A set of predefined tables hosted in a separate dir in HDFS.
> - A table is only 1 region, not splittable
> - Not assigned through regular assignment
> - Hosted only on 1 server (typically master)
> - Has a dedicated WAL.
> - A service does WAL recovery + fencing for these tables.
> This has the benefit of using a region to keep the data, but frees us to
> re-implement caching and we can use the same WAL / Memstore / Recovery
> mechanisms that are battle-tested.
>
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