* Add top-level `Conn`. Fixes#296.
This is a little different than the API rnewman and I originally
discussed in https://public.etherpad-mozilla.org/p/db-conn-thoughts.
A few notes:
- I was led to make a `Schema` instance the thing that is shared,
rather than a `db::DB`. It's possible that queries will want to
know the current transaction at some point (to prevent races, or to
query historical data), but that can be a future consideration.
- The generation number just allows for a cheap comparison. I don't
care to handle races to transact just yet; the long term plan might
be to make embedding applications responsible for avoiding races, or
we might handle queuing transactions and yielding report futures in
Mentat itself.
- The sharing of the partition maps is a little more subtle than
expected. Partition maps are volatile: a successful Mentat
transaction always advances the :db.part/tx partition, so it's not
worth passing references around. This means that consumers must
clone in order to maintain just a single clone per transaction.
Clean some cruft.
* Review comments.
* Pre: Drop unneeded tx0 from search results.
* Pre: Don't require a schema in some of the DB code.
The idea is to separate the transaction applying code, which is
schema-aware, from the concrete storage code, which is just concerned
with getting bits onto disk.
* Pre: Only reference Schema, not DB, in debug module.
This is part of a larger separation of the volatile PartitionMap,
which is modified every transaction, from the stable Schema, which is
infrequently modified.
* Pre: Fix indentation.
* Extract part of DB to new SchemaTypeChecking trait.
* Extract part of DB to new PartitionMapping trait.
* Pre: Don't expect :db.part/tx partition to advance when tx fails.
This fails right now, because we allocate tx IDs even when we shouldn't.
* Sketch a db interface without DB.
* Add ValueParseError; use error-chain in tx-parser.
This can be simplified when
https://github.com/Marwes/combine/issues/86 makes it to a published
release, but this unblocks us for now. This converts the `combine`
error type `ParseError<&'a [edn::Value]>` to a type with owned
`Vec<edn::Value>` collections, re-using `edn::Value::Vector` for
making them `Display`.
* Pre: Accept Borrow<Schema> instead of just &Schema in debug module.
This makes it easy to use Rc<Schema> or Arc<Schema> without inserting
&* sigils throughout the code.
* Use error-chain in query-parser.
There are a few things to point out here:
- the fine grained error types have been flattened into one crate-wide
error type; it's pretty easy to regain the granularity as needed.
- edn::ParseError is automatically lifted to
mentat_query_parser::errors::Error;
- we use mentat_parser_utils::ValueParser to maintain parsing error
information from `combine`.
* Patch up top-level.
* Review comment: Only `borrow()` once.
* Pre: Implement batch [a v] pair lookup.
* Pre: Add InternSet for sharing ref-counted handles to large values.
* Pre: Derive more for Entity.
* Pre: Return DB from creating; return TxReport from transact.
I explicitly am not supporting opening existing databases yet, let
alone upgrading databases from earlier versions. That can follow fast
once basic transactions are supported.
* Pre: Parse string temporary ID entities; remove ValueOrLookupRef.
This adds TempId entities, but we can't disambiguate String temporary
IDs from values without the use of the schema, so there's no new value
branch. Similarly, we can't disambiguate lookup-ref values from two
element list values without a schema, so we remove this entirely.
We'll handle the ambiguity later in the transactor.
* Persist partitions to SQL store; allocate transaction ID. (#186)
* Post: Test upserting with vectors.
This converts an existing test to EDN:
84a80f40f5/test/datomish/db_test.cljc (L193).
* Implement tempid upsert resolution algorithm. (#184)
* Post: Separate Tx out of DB.
This is very preliminary, since we don't have a real connection type
to manage transactions and their metadata yet.
* Post: Comment on implementation choices in the transactor.
* Review comment: Put long use lists on separate lines.
* Review comment: Accept String: Borrow<S> instead of just String.
* Review comment: Address nits.