# Change Log

## v0.13.0

### Breaking Changes

* Write-ahead log format changed (not backward compatible).

### Major Features and Improvements

* [Enterprise Ed.] Authentication and authorization support.
* [Enterprise Ed.] Kafka integration.
* Add `EXPLAIN` clause to openCypher

## v0.12.0

### Breaking Changes

* Snapshot format changed (not backward compatible).

### Major Features and Improvements

* Improved Id Cypher function.
* Added string functions to openCypher (`lTrim`, `left`, `rTrim`, `replace`,
 `reverse`, `right`, `split`, `substring`, `toLower`, `toUpper`, `trim`).
* Added `timestamp` function to openCypher.
* Added support for dynamic property access with `[]` operator.

## v0.11.0

### Major Features and Improvements

* [Enterprise Ed.] Improve Cartesian support in distributed queries.
* [Enterprise Ed.] Improve distributed execution of BFS.
* [Enterprise Ed.] Dynamic graph partitioner added.
* Static nodes/edges id generators exposed through the Id Cypher function.
* Properties on disk added.
* Telemetry added.
* SSL support added.
* `toString` function added.

### Bug Fixes and Other Changes

* Document issues with Docker on OS X.
* Add BFS and Dijkstra's algorithm examples to documentation.

## v0.10.0

### Breaking Changes

* Snapshot format changed (not backward compatible).

### Major Features and Improvements

* [Enterprise Ed.] Distributed storage and execution.
* `reduce` and `single` functions added to openCypher.
* `wShortest` edge expansion added to openCypher.
* Support packaging RPM on CentOS 7.

### Bug Fixes and Other Changes

* Report an error if updating a deleted element.
* Log an error if reading info on available memory fails.
* Fix a bug when `MATCH` would stop matching if a result was empty, but later
  results still contain data to be matched. The simplest case of this was the
  query: `UNWIND [1,2,3] AS x MATCH (n :Label {prop: x}) RETURN n`. If there
  was no node `(:Label {prop: 1})`, then the `MATCH` wouldn't even try to find
  for `x` being 2 or 3.
* Report an error if trying to compare a property value with something that
  cannot be stored in a property.
* Fix crashes in some obscure cases.
* Commit log automatically garbage collected.
* Add minor performance improvements.

## v0.9.0

### Breaking Changes

* Snapshot format changed (not backward compatible).
* Snapshot configuration flags changed, general durability flags added.

### Major Features and Improvements

* Write-ahead log added.
* `nodes` and `relationships` functions added.
* `UNION` and `UNION ALL` is implemented.
* Concurrent index creation is now enabled.

### Bug Fixes and Other Changes


## v0.8.0

### Major Features and Improvements

* CASE construct (without aggregations).
* Named path support added.
* Maps can now be stored as node/edge properties.
* Map indexing supported.
* `rand` function added.
* `assert` function added.
* `counter` and `counterSet` functions added.
* `indexInfo` function added.
* `collect` aggregation now supports Map collection.
* Changed the BFS syntax.

### Bug Fixes and Other Changes

* Use \u to specify 4 digit codepoint and \U for 8 digit
* Keywords appearing in header (named expressions) keep original case.
* Our Bolt protocol implementation is now completely compatible with the protocol version 1 specification. (https://boltprotocol.org/v1/)
* Added a log warning when running out of memory and the `memory_warning_threshold` flag
* Edges are no longer additionally filtered after expansion.

## v0.7.0

### Major Features and Improvements

* Variable length path `MATCH`.
* Explicitly started transactions (multi-query transactions).
* Map literal.
* Query parameters (except for parameters in place of property maps).
* `all` function in openCypher.
* `degree` function in openCypher.
* User specified transaction execution timeout.

### Bug Fixes and Other Changes

* Concurrent `BUILD INDEX` deadlock now returns an error to the client.
* A `MATCH` preceeded by `OPTIONAL MATCH` expansion inconsistencies.
* High concurrency Antlr parsing bug.
* Indexing improvements.
* Query stripping and caching speedups.

## v0.6.0

### Major Features and Improvements

* AST caching.
* Label + property index support.
* Different logging setup & format.

## v0.5.0

### Major Features and Improvements

* Use label indexes to speed up querying.
* Generate multiple query plans and use the cost estimator to select the best.
* Snapshots & Recovery.
* Abandon old yaml configuration and migrate to gflags.
* Query stripping & AST caching support.

### Bug Fixes and Other Changes

* Fixed race condition in MVCC. Hints exp+aborted race condition prevented.
* Fixed conceptual bug in MVCC GC. Evaluate old records w.r.t. the oldest.
  transaction's id AND snapshot.
* User friendly error messages thrown from the query engine.

## Build 837

### Bug Fixes and Other Changes

* List indexing supported with preceeding IN (for example in query `RETURN 1 IN [[1,2]][0]`).

## Build 825

### Major Features and Improvements

* RETURN *, count(*), OPTIONAL MATCH, UNWIND, DISTINCT (except DISTINCT in aggregate functions), list indexing and slicing, escaped labels, IN LIST operator, range function.

### Bug Fixes and Other Changes

* TCP_NODELAY -> import should be faster.
* Clear hint bits.

## Build 783

### Major Features and Improvements

* SKIP, LIMIT, ORDER BY.
* Math functions.
* Initial support for MERGE clause.

### Bug Fixes and Other Changes

* Unhandled Lock Timeout Exception.

## Build 755

### Major Features and Improvements

* MATCH, CREATE, WHERE, SET, REMOVE, DELETE.