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https://issues.apache.org/jira/browse/HBASE-13260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14520023#comment-14520023
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stack commented on HBASE-13260:
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[~enis]
bq. A pure FSHLog based proc store ...
What is this? This sounds like a nice compromise where we get to reuse existing
code.
bq. ....but the HRegion's concurrency
Yeah, need to fix that big time (Is this the [~eclark] lockless write work?)
Going the region-store path, there would still be the millions of extra
ancilliary objects created and their associated churn/GC that we'd need to deal
with.
bq. Whether to go with the wal based one or region based one is a question of
the design of proc-based assignment since for DDL ops it does not matter.
Unfortunately it is not formalized yet.
True. But we do know that the less friction our store takes, the faster our
assign will run.
bq. If we end up splitting meta, we can even do proc store on meta.
An RPC to the store complicates consistency and will add lag. I suggest we not
go this route and that an in-process store is actually required if we want fast
assign (Just the final states are published in hbase:meta).
Agree this is an interesting experiment to be pursued further (I like your
sharding trick). What to do for 1.1 though? (I suggest we just go WAL-store).
> 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_bench.patch, 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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