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Add Sequence Numbers and enforce Primary Terms #14651

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@bleskes bleskes commented Nov 10, 2015

This PR (against the feature/seq_no branch) adds a counter to each write operation on a shard. This sequence numbers is indexed into lucene using doc values, for now (we will probably require indexing to support range searchers in the future).

On top of this, primary term semantics are enforced and shards will refuse write operation coming from an older primary.

Other notes:

  • The add SequenceServiceNumber is just a skeleton and will be replaced with much heavier one, once we have all the building blocks (i.e., checkpoints).
  • I completely ignored recovery - for this we will need checkpoints as well.
  • A new based class is introduced for all single doc write operations. This is handy to unify common logic (like toXContent).
  • For now, we don't use seq# as versioning. We could in the future.

Relates to #10708

@jasontedor jasontedor assigned ahardy and jasontedor and unassigned ahardy Nov 10, 2015
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core/src/main/java/org/elasticsearch/action/DocWriteResponse.java Outdated
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can this somehow implement Writeable here or rather at the parent and make all the members final?

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I was trying to keep the same patterns as before to keep the change small. Will give it a shot.

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I had a look and this impossible without changing our network infra as well. This inherits from TransportResponse which implements Streamable, i.e., the readFrom has different semantics and returns void.

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s1monw commented Nov 10, 2015

looks great I left some comments

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Nits: "based class" -> "base class" and "involves are a" -> "involves a"

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bleskes commented Nov 13, 2015

@jasontedor can you take another look?

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Should this have a comment that it's for serialization?

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@bleskes bleskes Nov 19, 2015

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will do. Also made it protected.

@clintongormley clintongormley changed the title Add Sequence Numbers and an enforce Primary Terms Add Sequence Numbers and enforce Primary Terms Nov 16, 2015
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Do you think it would be clearer if the -1L that are now scattered in a few places (e.g., UpdateResponse, among a few others) were changed to refer to some constant field?

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core/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java
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Nice. :)

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jasontedor commented Nov 18, 2015

@bleskes I have a few nits, and some concerns about the -1s. It seems to be that there are at least two distinct uses of -1 (uninitialized, and no-op) and I wonder if they should be separated and use some constant fields? Otherwise, LGTM.

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bleskes commented Nov 19, 2015

@jasontedor +1 to the -1 :) . pushed another round. Also rebased on latest master so we can sue the writeZLong thing.

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jasontedor commented Nov 19, 2015

LGTM.

bleskes added a commit that referenced this pull request Nov 19, 2015
@bleskes
Add Sequence Numbers and enforce Primary Terms
5fb0f9a 
Adds a counter to each write operation on a shard. This sequence numbers is indexed into lucene using doc values, for now (we will probably require indexing to support range searchers in the future).

On top of this, primary term semantics are enforced and shards will refuse write operation coming from an older primary.

Other notes:
- The add SequenceServiceNumber is just a skeleton and will be replaced with much heavier one, once we have all the building blocks (i.e., checkpoints).
- I completely ignored recovery - for this we will need checkpoints as well.
- A new based class is introduced for all single doc write operations. This is handy to unify common logic (like toXContent).
- For now, we don't use seq# as versioning. We could in the future.

Relates to #10708
Closes #14651
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bleskes commented Nov 19, 2015

Merged into feature/seq_no. Thanks @jasontedor.

@bleskes bleskes closed this Nov 19, 2015
@bleskes bleskes deleted the seq_no_counter branch November 19, 2015 14:36
@bleskes bleskes mentioned this pull request Nov 24, 2015
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@bleskes bleskes mentioned this pull request Mar 10, 2016
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bleskes added a commit to bleskes/elasticsearch that referenced this pull request Mar 25, 2016
@bleskes
Port Primary Terms to master elastic#17044
fe43eef 
Primary terms is a way to make sure that operations replicated from stale primary are rejected by shards following a newly elected primary.

Original PRs adding this to the seq# feature branch elastic#14062 , elastic#14651 . Unlike those PR, here we take a different approach (based on newer code in master) where the primary terms are stored in the meta data only (and not in `ShardRouting` objects).

Relates to elastic#17038

Closes elastic#17044
@clintongormley clintongormley added :Engine :Distributed Indexing/Engine Anything around managing Lucene and the Translog in an open shard. and removed :Sequence IDs labels Feb 14, 2018
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