project-m36-0.2: Changelog.markdown

# 2017-08-01

## autoMergeToHead

In preparation for the simpler monad client API, ProjectM36.Client now includes a server-side merge for new transactions called "[automerge](https://github.com/agentm/project-m36/issues/33)". This feature should reduce head contention in cases where new transactions can be simply merged to the head without additional processing. The trade-off is reduced ```TransactionIsNotAHeadError```s but an increased chance of merge errors. The feature operates similarly to a server-side git rebase.

## critical bug in merging

Successfully merged transactions did not have their constraints validated. Fixed.

# 2017-06-12

## add file locking

This [feature](#102) allows Project:M36 database directories to be shared amongst multiple Project:M36 processes. This is similar to how SQLite operates except that the remote server mode supports the feature as well. This could allow, for example, multi-master, file-based replication across Windows shares or NFS.

[Documentation](/docs/replication.markdown)

# 2016-11-30

## add functional dependency macro

Date demonstrates two ways to implement functional dependencies as constraints on page 21 in "Database Design and Relational Theory". A similar macros is now implemented in the tutd interpreter.

```funcdep sname_status (sname) -> (status) s```

[Documentation](/docs/tutd_tutorial.markdown#functional-dependencies)

# 2016-09-07

## add TransGraphRelationalExpr

The TransGraphRelationalExpr allows queries against all past states of the database.

The following example executes a query against two different committed transactions using syntax similar to that of git for graph traversal:
```:showtransgraphexpr s@master~ join sp@master```

[Documentation](/docs/transgraphrelationalexpr.markdown)