IMPORTANT: This is an alpha release and is intended for _testing purposes only_. Indices created in this version will *not be compatible with Elasticsearch 5.0.0 GA*. Upgrading 5.0.0-alpha2 to any other version is not supported.
* Create registration methods for aggregations similar to those for queries {pull}17653[#17653] (issues: {issue}17085[#17085], {issue}17389[#17389])
* Turn RestChannel into an interface {pull}17643[#17643] (issue: {issue}17133[#17133])
* Remove PROTOTYPEs from QueryBuilders {pull}17632[#17632] (issue: {issue}17085[#17085])
* Remove registerQueryParser {pull}17608[#17608]
* ParseField#getAllNamesIncludedDeprecated to not return duplicate names {pull}17504[#17504]
* Rework a query parser and improve registration {pull}17458[#17458]
* Clean up QueryParseContext and don't hold it inside QueryRewrite/ShardContext {pull}17417[#17417]
Mapping::
* Automatically upgrade analyzed strings with an analyzer to `text`. {pull}17861[#17861]
* Support dots in field names when mapping already exists {pull}17759[#17759] (issue: {issue}15951[#15951])
* Use the new points API to index numeric fields. {pull}17746[#17746] (issues: {issue}11513[#11513], {issue}16751[#16751], {issue}17007[#17007], {issue}17700[#17700])
* Simplify AllEntries, AllField and AllFieldMapper: {pull}17613[#17613]
* Remove unnecessary sleep from init script restart {pull}17966[#17966]
* Explicitly set packaging permissions {pull}17912[#17912] (issue: {issue}17634[#17634])
* Allow configuring Windows service name, description and user {pull}17312[#17312]
* rpm uses non-portable `--system` flag to `useradd` {pull}14596[#14596] (issue: {issue}14211[#14211])
Percolator::
* PercolatorQueryBuilder cleanup by using MemoryIndex#fromDocument(...) helper {pull}17669[#17669] (issue: {issue}9386[#9386])
Plugins::
* Cli: Improve output for usage errors {pull}17938[#17938]
* Cli: Add verbose output with zip url when installing plugin {pull}17662[#17662] (issue: {issue}17529[#17529])
Query DSL::
* Add MatchNoDocsQuery, a query that matches no documents and prints the reason why in the toString method. {pull}17780[#17780]
* Adds `ignore_unmapped` option to geo queries {pull}17751[#17751]
* Adds `ignore_unmapped` option to nested and P/C queries {pull}17748[#17748]
* SimpleQueryParser should call MappedFieldType.termQuery when appropriate. {pull}17678[#17678]
REST::
* Allow JSON with unquoted field names by enabling system property {pull}17801[#17801] (issue: {issue}17674[#17674])
Recovery::
* TransportNodesListGatewayStartedShards should fall back to disk based index metadata if not found in cluster state {pull}17663[#17663] (issue: {issue}17630[#17630])
Reindex API::
* Properly mark reindex's child tasks as child tasks {pull}17770[#17770]
Search::
* Fail query if it contains very large rescores {pull}17917[#17917] (issue: {issue}17522[#17522])
Settings::
* Switch to registered Settings for all IndexingMemoryController settings {pull}17778[#17778] (issue: {issue}17442[#17442])
Stats::
* Add points to SegmentStats. {pull}17775[#17775] (issue: {issue}16974[#16974])
* Remove FieldStats.Float. {pull}17749[#17749]
* Show configured and remaining delay for an unassigned shard. {pull}17515[#17515] (issue: {issue}17372[#17372])
Store::
* Use `mmapfs` by default. {pull}17616[#17616] (issue: {issue}16983[#16983])
Suggesters::
* Add bwc support for reading pre-5.0 completion index {pull}17602[#17602]
Task Manager::
* Move parentTaskId into TransportRequest {pull}17872[#17872]
* Shorten the serialization of the empty TaskId {pull}17870[#17870]
* Expose whether a task is cancellable in the _tasks list API {pull}17464[#17464] (issue: {issue}17369[#17369])
[[bug-5.0.0-alpha2]]
[float]
=== Bug fixes
Aggregations::
* Adds serialisation of sigma to extended_stats_bucket pipeline aggregation {pull}17703[#17703] (issue: {issue}17701[#17701])
* Fixes NPE when no window is specified in moving average request {pull}17556[#17556] (issue: {issue}17516[#17516])
* Fixes Filter and FiltersAggregation to work with empty query {pull}17542[#17542] (issue: {issue}17518[#17518])
* ExtendedStatsAggregator should also pass sigma to emtpy aggs. {pull}17388[#17388] (issue: {issue}17362[#17362])