I have seen this question a couple times already, most recently at
https://twitter.com/dimosr7/status/973872744965332993
I tried to keep the explanation as simple as I could, which is not always easy
as this is a matter of trade-offs.
Currently we have a fairly complicated logic in the engine constructor logic to deal with all the
various ways we want to mutate the lucene index and translog we're opening.
We can:
1) Create an empty index
2) Use the lucene but create a new translog
3) Use both
4) Force a new history uuid in all cases.
This leads complicated code flows which makes it harder and harder to make sure we cover all the
corner cases. This PR tries to take another approach. Constructing an InternalEngine always opens
things as they are and all needed modifications are done by static methods directly on the
directory, one at a time.
The current docs on [Indices APIs: PUT Mapping](https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-put-mapping.html) suggests that a having number of different mapping types per index is still possible in elasticsearch versions > 6.0.0 although they have been [removed](https://www.elastic.co/guide/en/elasticsearch/reference/current/removal-of-types.html). The console code has already been updated accordingly but notes (2) and (3) on the console code still name the `user` mapping type.
This PR updates the list with notes after the console code, as well as the first sentence of the docs
to avoid confusion. Also, I have removed the second command from the console code as it no
longer holds any value if the docs are solely on the `_doc` mapping.
Currently the Translog constructor is capable both of opening an existing translog and creating a
new one (deleting existing files). This PR separates these two into separate code paths. The
constructors opens files and a dedicated static methods creates an empty translog.
Allowing `_doc` as a type will enable users to make the transition to 7.0
smoother since the index APIs will be `PUT index/_doc/id` and `POST index/_doc`.
This also moves most of the documentation to `_doc` as a type name.
Closes#27750Closes#27751
Add an index level setting `index.analyze.max_token_count` to control
the number of generated tokens in the _analyze endpoint.
Defaults to 10000.
Throw an error if the number of generated tokens exceeds this limit.
Closes#27038
Today we require users to prepare their indices for split operations.
Yet, we can do this automatically when an index is created which would
make the split feature a much more appealing option since it doesn't have
any 3rd party prerequisites anymore.
This change automatically sets the number of routinng shards such that
an index is guaranteed to be able to split once into twice as many shards.
The number of routing shards is scaled towards the default shard limit per index
such that indices with a smaller amount of shards can be split more often than
larger ones. For instance an index with 1 or 2 shards can be split 10x
(until it approaches 1024 shards) while an index created with 128 shards can only
be split 3x by a factor of 2. Please note this is just a default value and users
can still prepare their indices with `index.number_of_routing_shards` for custom
splitting.
NOTE: this change has an impact on the document distribution since we are changing
the hash space. Documents are still uniformly distributed across all shards but since
we are artificually changing the number of buckets in the consistent hashign space
document might be hashed into different shards compared to previous versions.
This is a 7.0 only change.
This change adds a new `_split` API that allows to split indices into a new
index with a power of two more shards that the source index. This API works
alongside the `_shrink` API but doesn't require any shard relocation before
indices can be split.
The split operation is conceptually an inverse `_shrink` operation since we
initialize the index with a _syntetic_ number of routing shards that are used
for the consistent hashing at index time. Compared to indices created with
earlier versions this might produce slightly different shard distributions but
has no impact on the per-index backwards compatibility. For now, the user is
required to prepare an index to be splittable by setting the
`index.number_of_routing_shards` at index creation time. The setting allows the
user to prepare the index to be splittable in factors of
`index.number_of_routing_shards` ie. if the index is created with
`index.number_of_routing_shards: 16` and `index.number_of_shards: 2` it can be
split into `4, 8, 16` shards. This is an intermediate step until we can make
this the default. This also allows us to safely backport this change to 6.x.
The `_split` operation is implemented internally as a DeleteByQuery on the
lucene level that is executed while the primary shards execute their initial
recovery. Subsequent merges that are triggered due to this operation will not be
executed immediately. All merges will be deferred unti the shards are started
and will then be throttled accordingly.
This change is intended for the 6.1 feature release but will not support pre-6.1
indices to be split unless these indices have been shrunk before. In that case
these indices can be split backwards into their original number of shards.
This commit reformats a paragraph in the template docs to fit in 80
columns as for the rest of the doc, and as-is a standard that we loosely
adhere to.
This commit clarifies the interaction between settings specified in a
create index request, and those that would come from any templates that
apply to the create index request.
Relates #26994
Adds the wait_for_active_shards parameter to the index open command. Similar to the index creation command, the index open command will now, by default, wait until the primaries have been allocated.
Closes#20937
The new ops based recovery, introduce as part of #10708, is based on the assumption that all operations below the global checkpoint known to the replica do not need to be synced with the primary. This is based on the guarantee that all ops below it are available on primary and they are equal. Under normal operations this guarantee holds. Sadly, it can be violated when a primary is restored from an old snapshot. At the point the restore primary can miss operations below the replica's global checkpoint, or even worse may have total different operations at the same spot. This PR introduces the notion of a history uuid to be able to capture the difference with the restored primary (in a follow up PR).
The History UUID is generated by a primary when it is first created and is synced to the replicas which are recovered via a file based recovery. The PR adds a requirement to ops based recovery to make sure that the history uuid of the source and the target are equal. Under normal operations, all shard copies will stay with that history uuid for the rest of the index lifetime and thus this is a noop. However, it gives us a place to guarantee we fall back to file base syncing in special events like a restore from snapshot (to be done as a follow up) and when someone calls the truncate translog command which can go wrong when combined with primary recovery (this is done in this PR).
We considered in the past to use the translog uuid for this function (i.e., sync it across copies) and thus avoid adding an extra identifier. This idea was rejected as it removes the ability to verify that a specific translog really belongs to a specific lucene index. We also feel that having a history uuid will serve us well in the future.
Get mappings HEAD requests incorrectly return a content-length header of
0. This commit addresses this by removing the special handling for get
mappings HEAD requests, and just relying on the general mechanism that
exists for handling HEAD requests in the REST layer.
Relates #23192
This removes the parsing of things like `GET /idx/_aliases,_mappings`, instead,
a user must choose between retriving all index metadata with `GET /idx`, or only
a specific form such as `GET /idx/_settings`.
Relates to (and is a prerequisite of) #24437
The response is attempting to illustrate the sync_id marker, but in
the test the index is too "fresh" to have a sync marker. So the test
needs to execute a sync flush behind the scenes so that the marker
is present
This adds the `index.mapping.single_type` setting, which enforces that indices
have at most one type when it is true. The default value is true for 6.0+ indices
and false for old indices.
Relates #15613
Elasticsearch v5.0.0 uses allocation IDs to safely allocate primary shards whereas prior versions of ES used a version-based mode instead. Elasticsearch v5 still has support for version-based primary shard allocation as it needs to be able to load 2.x shards. ES v6 can drop the legacy support.
This change also removes the reference to the difference bewteen full name and index name.
They are always the same since 2.x and `name` does not refer anymore to `author.name` automatically.
A simple pattern must be used instead.
Remove redundant code that checks the field name twice.
Relates to #22024
On top of documentation, the PR adds deprecation loggers and deals with the resulting warning headers.
The yaml test is set exclude versions up to 6.0. This is need to make sure bwc tests pass until this is backported to 5.2.0 . Once that's done, I will change the yaml test version limits
Today we try to pull stats from index writer but we do not get a
consistent view of stats. Under heavy indexing, this inconsistency can
be very skewed indeed. In particular, it can lead to the number of
deleted docs being reported as negative and this leads to serialization
issues. Instead, we should provide a consistent view of the stats by
using an index reader.
Relates #22317
Today when parsing a stats request, Elasticsearch silently ignores
incorrect metrics. This commit removes lenient parsing of stats requests
for the nodes stats and indices stats APIs.
Relates #21417
* Allows for an array of index template patterns to be provided to an
index template, and rename the field from 'template' to 'index_pattern'.
Closes#20690
* Params improvements to Cluster Health API wait for shards
Previously, the cluster health API used a strictly numeric value
for `wait_for_active_shards`. However, with the introduction of
ActiveShardCount and the removal of write consistency level for
replication operations, `wait_for_active_shards` is used for
write operations to represent values for ActiveShardCount. This
commit moves the cluster health API's usage of `wait_for_active_shards`
to be consistent with its usage in the write operation APIs.
This commit also changes `wait_for_relocating_shards` from a
numeric value to a simple boolean value `wait_for_no_relocating_shards`
to set whether the cluster health operation should wait for
all relocating shards to complete relocation.
* Addresses code review comments
* Don't be lenient if `wait_for_relocating_shards` is set
While removing an index isn't actually an alias action, if we add
an alias action that deletes an index then we can delete and index
and add an alias with the same name as the index atomically, in
the same cluster state update.
Closes#20064
Currently both `PUT` and `POST` can be used to create indices. This commit
removes support for `POST index_name` so that we can use it to index documents
with auto-generated ids once types are removed.
Relates #15613
In the example there was a alias removed and then a different alias created for the same index, but I think actually swapping a index by another one for the same alias would make more sense as an example here.
Adds `warnings` syntax to the yaml test that allows you to expect
a `Warning` header that looks like:
```
- do:
warnings:
- '[index] is deprecated'
- quotes are not required because yaml
- but this argument is always a list, never a single string
- no matter how many warnings you expect
get:
index: test
type: test
id: 1
```
These are accessible from the docs with:
```
// TEST[warning:some warning]
```
This should help to force you to update the docs if you deprecate
something. You *must* add the warnings marker to the docs or the build
will fail. While you are there you *should* update the docs to add
deprecation warnings visible in the rendered results.
Add parser for anonymous char_filters/tokenizer/token_filters
Using Settings in AnalyzeRequest for anonymous definition
Add breaking changes document
Closed#8878
Node IDs are currently randomly generated during node startup. That means they change every time the node is restarted. While this doesn't matter for ES proper, it makes it hard for external services to track nodes. Another, more minor, side effect is that indexing the output of, say, the node stats API results in creating new fields due to node ID being used as keys.
The first approach I considered was to use the node's published address as the base for the id. We already [treat nodes with the same address as the same](https://github.com/elastic/elasticsearch/blob/master/core/src/main/java/org/elasticsearch/discovery/zen/NodeJoinController.java#L387) so this is a simple change (see [here](https://github.com/elastic/elasticsearch/compare/master...bleskes:node_persistent_id_based_on_address)). While this is simple and it works for probably most cases, it is not perfect. For example, if after a node restart, the node is not able to bind to the same port (because it's not yet freed by the OS), it will cause the node to still change identity. Also in environments where the host IP can change due to a host restart, identity will not be the same.
Due to those limitation, I opted to go with a different approach where the node id will be persisted in the node's data folder. This has the upside of connecting the id to the nodes data. It also means that the host can be adapted in any way (replace network cards, attach storage to a new VM). I
It does however also have downsides - we now run the risk of two nodes having the same id, if someone copies clones a data folder from one node to another. To mitigate this I changed the semantics of the protection against multiple nodes with the same address to be stricter - it will now reject the incoming join if a node exists with the same id but a different address. Note that if the existing node doesn't respond to pings (i.e., it's not alive) it will be removed and the new node will be accepted when it tries another join.
Last, and most importantly, this change requires that *all* nodes persist data to disk. This is a change from current behavior where only data & master nodes store local files. This is the main reason for marking this PR as breaking.
Other less important notes:
- DummyTransportAddress is removed as we need a unique network address per node. Use `LocalTransportAddress.buildUnique()` instead.
- I renamed `node.add_lid_to_custom_path` to `node.add_lock_id_to_custom_path` to avoid confusion with the node ID which is now part of the `NodeEnvironment` logic.
- I removed the `version` paramater from `MetaDataStateFormat#write` , it wasn't really used and was just in the way :)
- TribeNodes are special in the sense that they do start multiple sub-nodes (previously known as client nodes). Those sub-nodes do not store local files but derive their ID from the parent node id, so they are generated consistently.
Today we allow to shrink to 1 shard but that might not be possible due to
too many document or a single shard doesn't meet the requirements for the index.
The logic can be expanded to N shards if the source index shards is a multiple of N.
This guarantees that there are not hotspots created due to different number of shards
being shrunk into one.
Today we use `index.routing.allocation.include._id` to filter the allocation
for the shrink target index. That has the sideeffect that the user has to
delete that setting / change it once the primary has been recovered (shrink is done)
This PR adds a dedicated filter that can only be set internally that only filters
allocation for unassigned shards.
This adds a low level primitive operations to shrink an existing
index into a new index with a single shard. This primitive expects
all shards of the source index to allocated on a single node. Once the target index is initializing on the shrink node it takes a snapshot of the source index shards and copies all files into the target indices data folder. An [optimization](https://issues.apache.org/jira/browse/LUCENE-7300) coming in Lucene 6.1 will also allow for optional constant time copy if hard-links are supported by the filesystem. All mappings are merged into the new indexes metadata once the snapshots have been taken on the merge node.
To shrink an existing index all shards must be moved to a single node (one instance of each shard) and the index must be read-only:
```BASH
$ curl -XPUT 'http://localhost:9200/logs/_settings' -d '{
"settings" : {
"index.routing.allocation.require._name" : "shrink_node_name",
"index.blocks.write" : true
}
}
```
once all shards are started on the shrink node. the new index can be created via:
```BASH
$ curl -XPUT 'http://localhost:9200/logs/_shrink/logs_single_shard' -d '{
"settings" : {
"index.codec" : "best_compression",
"index.number_of_replicas" : 1
}
}'
```
This API will perform all needed check before the new index is created and selects the shrink node based on the allocation of the source index. This call returns immediately, to monitor shrink progress the recovery API should be used since all copy operations are reflected in the recovery API with byte copy progress etc.
The shrink operation does not modify the source index, if a shrink operation should
be canceled or if the shrink failed, the target index can simply be deleted and
all resources are released.
Adds infrastructure so `gradle :docs:check` will extract tests from
snippets in the documentation and execute the tests. This is included
in `gradle check` so it should happen on CI and during a normal build.
By default each `// AUTOSENSE` snippet creates a unique REST test. These
tests are executed in a random order and the cluster is wiped between
each one. If multiple snippets chain together into a test you can annotate
all snippets after the first with `// TEST[continued]` to have the
generated tests for both snippets joined.
Snippets marked as `// TESTRESPONSE` are checked against the response
of the last action.
See docs/README.asciidoc for lots more.
Closes#12583. That issue is about catching bugs in the docs during build.
This catches *some* bugs in the docs during build which is a good start.
Closes#17513
The current example in the documentation for Index Templates lacks any properties values. This is helpful to many devs that aren't sure how to take a regular Index Mapping and convert it to a template.
Use 'includeSegmentFileSizes' as the flag name to report disk usage.
Added test that verifies reported segment disk usage is growing accordingly after adding a document.
Documentation: Reference the new parameter as part of indices stats.
Warmers are now barely useful and will be removed in 3.0. Note that this only
removes the warmer API and query-based warmers. We still have warmers internally
for eg. global ordinals.
Close#15607
Resolves conflicts between parent routing and alias routing with the following rule:
* The parent routing is ignored if there is an alias routing that matches the request.
Closes#3068
This adds an API for force merging lucene segments. The `/_optimize` API is now
deprecated and replaced by the `/_forcemerge` API, which has all the same flags
and action, just a different name.
Closed indices are currently out of scope for snapshots and shard migration,
and can cause issues in managed environments – where closing an index does
not necessarily make sense, as it still consumes the managed environment's storage quota.
This commit adds an option to dynamically disable closing indices via node or cluster settings.
Closes#14168
This allows `path.shared_data` to be added to the security manager while
still allowing a custom `data_path` for indices using shadow replicas.
For example, configuring `path.shared_data: /tmp/foo`, then created an
index with:
```
POST /myindex
{
"index": {
"number_of_shards": 1,
"number_of_replicas": 1,
"data_path": "/tmp/foo/bar/baz",
"shadow_replicas": true
}
}
```
The index will then reside in `/tmp/foo/bar/baz`.
`path.shared_data` defaults to `null` if not specified.
Resolves#12714
Relates to #11065
Store information reports on which nodes shard copies exist, the shard
copy version, indicating how recent they are, and any exceptions
encountered while opening the shard index or from earlier engine failure.
closes#10952
This PR is a simple doc patch to explicitly mention with an example of
how to create an alias using a glob pattern. This comes up from
time-to-time with our customers and in the community and although
mentioned in the documentation already, is not obvious.
Also mention that the alias will not auto-update as indices matching the
glob change.
Closes#12175Closes#12176
In order to be more consistent with what they do, the query cache has been
renamed to request cache and the filter cache has been renamed to query
cache.
A known issue is that package/logger names do no longer match settings names,
please speak up if you think this is an issue.
Here are the settings for which I kept backward compatibility. Note that they
are a bit different from what was discussed on #11569 but putting `cache` before
the name of what is cached has the benefit of making these settings consistent
with the fielddata cache whose size is configured by
`indices.fielddata.cache.size`:
* index.cache.query.enable -> index.requests.cache.enable
* indices.cache.query.size -> indices.requests.cache.size
* indices.cache.filter.size -> indices.queries.cache.size
Close#11569
This commit consolidates several abstractions on the shard level in
ordinary classes not managed by the shard level guice injector.
Several classes have been collapsed into IndexShard and IndexShardGatewayService
was cleaned up to be more lightweight and self-contained. It has also been moved into
the index.shard package and it's operation is renamed from recovery from "gateway" to recovery
from "store" or "shard_store".
Closes#11847
Adrien Grand
Boaz Leskes
Joost Rothweiler
Arne Neumann
Mayya Sharipova
Simon Willnauer
Nhat
Jason Tedor
Pius
Alexander Kazakov
Tanguy Leroux
markwalkom
Clinton Gormley
Wesley Merkel
Jun Ohtani
javanna
Sergey Novikov
Lee Hinman
Brian Lesperance
glefloch
Zachary Tong
Zachary Tong
Emir Beganović
Himanshu Bhandoh
Ryan Ernst
Yannick Welsch
Jim Ferenczi
Shubham Aggarwal
Jeffery Bradberry
Sakthipriyan Vairamani
Alexander Lin
Chris Earle
Chris Earle
Lucas Bremgartner
Nik Everett
Ali Beyad
polyfractal
Ludo
Glen Smith
Areek Zillur
Folusho Oladipo
Sho Minagawa
Christoph Wurm
debadair
Simon Willnauer
Shane Connelly
Zack Dever
Josef Salyer
Mahmoud Lababidi
Camilo Díaz Repka
Dongjoon Hyun
Yannick Welsch
Brady Vidovic
Jason Veatch
Martijn van Groningen
Joshua Rich