Summary:
This is a proposal on how the WAL recovery process can be implemented so
that Deltas aren't accumulated, but instead applied in the same order
they are written to the WAL.
I *believe* that the only additional requirement on the system are
atomic transaction Begin/Commit/Abort. By atomic I mean that they are
present in the WAL in exactly the same ordering like in the transaciton
engine, to ensure the same commitability of original and recovery
transactions.
This could be a requirement for HA recovery. It is desirable that WAL
and HA log become the same thing, and the recovery process too.
Reviewers: mtomic, dgleich, mislav.bradac
Reviewed By: mislav.bradac
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1068
Summary: Remove two tx::Transaction methods that are not defined and never used.
Reviewers: dgleich
Reviewed By: dgleich
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1072
Summary:
Rpc client wasn't thread safe and required a lock before each rpc call.
The locking functionality is now incorporated in Rpc client.
Reviewers: mislav.bradac
Reviewed By: mislav.bradac
Differential Revision: https://phabricator.memgraph.io/D1056
Summary:
The current idea is that the same MG binary can be used for single-node,
distributed master and distributed worker. The transactional engine in
the single-node and distributed master is the same: it determines the
transactional time and exposes all the "global" functionalities. In the
distributed worker the "global" functions must contact the master.
Reviewers: dgleich, mislav.bradac, buda
Reviewed By: dgleich
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1013
Summary: Code simplification made possible by making `locks_` `mutable` in `tx::Transaction`.
Reviewers: dgleich, buda
Reviewed By: buda
Differential Revision: https://phabricator.memgraph.io/D1015
Summary:
This diff contains step 1:
- Remove clog exposure from tx::engine
- Reduce and cleanup tx::Engine API
All current functionality is kept, but the API is reduced. This is very
desirable because every function in tx::Engine will need to be
considered and implemented in both Master and Worker situations. The
less we have, the better.
Next step is exactly that: seeing how each of these functions behaves in
a distributed system and implementing accordingly.
Reviewers: dgleich, mislav.bradac, buda
Reviewed By: mislav.bradac
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1008
Summary:
My dear fellow Memgraphians. It's friday afternoon, and I am as ready to pop as WAL is to get reviewed...
What's done:
- Vertices and Edges have global IDs, stored in `VersionList`. Main storage is now a concurrent map ID->vlist_ptr.
- WriteAheadLog class added. It's based around buffering WAL::Op objects (elementraly DB changes) and periodically serializing and flusing them to disk.
- Snapshot recovery refactored, WAL recovery added. Snapshot format changed again to include necessary info.
- Durability testing completely reworked.
What's not done (and should be when we decide how):
- Old WAL file purging.
- Config refactor (naming and organization). Will do when we discuss what we want.
- Changelog and new feature documentation (both depending on the point above).
- Better error handling and recovery feedback. Currently it's all returning bools, which is not fine-grained enough (neither for errors nor partial successes, also EOF is reported as a failure at the moment).
- Moving the implementation of WAL stuff to .cpp where possible.
- Not sure if there are transactions being created outside of `GraphDbAccessor` and it's `BuildIndex`. Need to look into.
- True write-ahead logic (flag controlled): not committing a DB transaction if the WAL has not flushed it's data. We can discuss the gain/effort ratio for this feature.
Reviewers: buda, mislav.bradac, teon.banek, dgleich
Reviewed By: dgleich
Subscribers: mtomic, pullbot
Differential Revision: https://phabricator.memgraph.io/D958
Summary:
Warnings I ignored:
Creates a new stacktrace object and then dumps it
102.570384 (102.495075) E[1]: [src/utils/exceptions.hpp:116]: (performance) Variable 'stacktrace_' is assigned in constructor body. Consider performing initialization in initialization list.
102.570390 (102.495081) E[1]: [src/utils/exceptions.hpp:127]: (performance) Variable 'stacktrace_' is assigned in constructor body. Consider performing initialization in initialization list.
Used all over the codebase without explicit cast
102.570412 (102.495103) E[1]: [src/utils/stacktrace.hpp:14]: (style) Class 'Line' has a constructor with 1 argument that is not explicit.
Not really used anywhere before initialized:
102.570526 (102.495217) E[1]: [src/data_structures/concurrent/skiplist.hpp:467]: (warning) Member variable 'Accessor::preds' is not initialized in the constructor.
102.570530 (102.495221) E[1]: [src/data_structures/concurrent/skiplist.hpp:467]: (warning) Member variable 'Accessor::succs' is not initialized in the constructor.
Implicit conversions between types are used all over the codebase:
102.570548 (102.495239) E[1]: [src/storage/property_value.hpp:41]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570552 (102.495243) E[1]: [src/storage/property_value.hpp:42]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570557 (102.495248) E[1]: [src/storage/property_value.hpp:43]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570561 (102.495252) E[1]: [src/storage/property_value.hpp:44]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570566 (102.495257) E[1]: [src/storage/property_value.hpp:47]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570570 (102.495261) E[1]: [src/storage/property_value.hpp:50]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570578 (102.495269) E[1]: [src/storage/property_value.hpp:53]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570582 (102.495273) E[1]: [src/storage/property_value.hpp:57]: (style) Class 'PropertyValue' has a constructor with 1 argument that is not explicit.
102.570591 (102.495282) E[1]: [src/query/typed_value.hpp:80]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570596 (102.495287) E[1]: [src/query/typed_value.hpp:81]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570601 (102.495292) E[1]: [src/query/typed_value.hpp:82]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570605 (102.495296) E[1]: [src/query/typed_value.hpp:83]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570609 (102.495300) E[1]: [src/query/typed_value.hpp:89]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570614 (102.495305) E[1]: [src/query/typed_value.hpp:92]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570618 (102.495309) E[1]: [src/query/typed_value.hpp:95]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570623 (102.495314) E[1]: [src/query/typed_value.hpp:98]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570627 (102.495318) E[1]: [src/query/typed_value.hpp:102]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570632 (102.495323) E[1]: [src/query/typed_value.hpp:105]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570636 (102.495327) E[1]: [src/query/typed_value.hpp:108]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570641 (102.495332) E[1]: [src/query/typed_value.hpp:109]: (style) Class 'TypedValue' has a constructor with 1 argument that is not explicit.
102.570645 (102.495336) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:88]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570650 (102.495341) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:89]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570654 (102.495345) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:90]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570659 (102.495350) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:91]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570663 (102.495354) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:94]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570668 (102.495359) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:97]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570672 (102.495363) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:100]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570677 (102.495368) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:104]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570681 (102.495372) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:107]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570690 (102.495381) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:110]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
102.570694 (102.495385) E[1]: [src/communication/bolt/v1/decoder/decoded_value.hpp:113]: (style) Class 'DecodedValue' has a constructor with 1 argument that is not explicit.
CypherParser:
102.570767 (102.495458) E[1]: [src/query/frontend/opencypher/generated/CypherParser.h:69]: (style) Class 'CypherParser' has a constructor with 1 argument that is not explicit.
102.570772 (102.495463) E[1]: [src/query/frontend/opencypher/generated/CypherLexer.h:40]: (style) Class 'CypherLexer' has a constructor with 1 argument that is not explicit.
102.570776 (102.495467) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:86]: (style) The scope of the variable '_la' can be reduced.
102.570781 (102.495472) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:311]: (style) The scope of the variable '_la' can be reduced.
102.570785 (102.495476) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:402]: (style) The scope of the variable '_la' can be reduced.
102.570789 (102.495480) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:497]: (style) The scope of the variable '_la' can be reduced.
102.570797 (102.495488) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:778]: (style) The scope of the variable '_la' can be reduced.
102.570802 (102.495493) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:895]: (style) The scope of the variable '_la' can be reduced.
102.570806 (102.495497) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:991]: (style) The scope of the variable '_la' can be reduced.
102.570811 (102.495502) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:1190]: (style) The scope of the variable '_la' can be reduced.
102.570815 (102.495506) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:1274]: (style) The scope of the variable '_la' can be reduced.
102.570820 (102.495511) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:1393]: (style) The scope of the variable '_la' can be reduced.
102.570824 (102.495515) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:1570]: (style) The scope of the variable '_la' can be reduced.
102.570829 (102.495520) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:1695]: (style) The scope of the variable '_la' can be reduced.
102.570834 (102.495525) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:1800]: (style) The scope of the variable '_la' can be reduced.
102.570839 (102.495530) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:1903]: (style) The scope of the variable '_la' can be reduced.
102.570843 (102.495534) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:2019]: (style) The scope of the variable '_la' can be reduced.
102.570848 (102.495539) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:2228]: (style) The scope of the variable '_la' can be reduced.
102.570852 (102.495543) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:2542]: (style) The scope of the variable '_la' can be reduced.
102.570857 (102.495548) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:2797]: (style) The scope of the variable '_la' can be reduced.
102.570861 (102.495552) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:2966]: (style) The scope of the variable '_la' can be reduced.
102.570866 (102.495557) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:3067]: (style) The scope of the variable '_la' can be reduced.
102.570870 (102.495561) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:3289]: (style) The scope of the variable '_la' can be reduced.
102.570875 (102.495566) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:3295]: (style) The scope of the variable 'alt' can be reduced.
102.570879 (102.495570) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:3419]: (style) The scope of the variable '_la' can be reduced.
102.570884 (102.495575) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:3596]: (style) The scope of the variable '_la' can be reduced.
102.570888 (102.495579) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:3688]: (style) The scope of the variable '_la' can be reduced.
102.570893 (102.495584) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:3963]: (style) The scope of the variable '_la' can be reduced.
102.570897 (102.495588) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:4452]: (style) The scope of the variable '_la' can be reduced.
102.570902 (102.495593) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:4586]: (style) The scope of the variable '_la' can be reduced.
102.570906 (102.495597) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:4813]: (style) The scope of the variable '_la' can be reduced.
102.570911 (102.495602) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:4943]: (style) The scope of the variable '_la' can be reduced.
102.570918 (102.495609) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:5026]: (style) The scope of the variable '_la' can be reduced.
102.570923 (102.495614) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:5569]: (style) The scope of the variable '_la' can be reduced.
102.570928 (102.495619) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:5664]: (style) The scope of the variable '_la' can be reduced.
102.570932 (102.495623) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:5755]: (style) The scope of the variable '_la' can be reduced.
102.570937 (102.495628) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:5888]: (style) The scope of the variable '_la' can be reduced.
102.570941 (102.495632) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:6045]: (style) The scope of the variable '_la' can be reduced.
102.570946 (102.495637) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:6142]: (style) The scope of the variable '_la' can be reduced.
102.570950 (102.495641) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:6347]: (style) The scope of the variable '_la' can be reduced.
102.570955 (102.495646) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:6523]: (style) The scope of the variable '_la' can be reduced.
102.570959 (102.495650) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:6614]: (style) The scope of the variable '_la' can be reduced.
102.570964 (102.495655) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:6899]: (style) The scope of the variable '_la' can be reduced.
102.570968 (102.495659) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:6992]: (style) The scope of the variable '_la' can be reduced.
102.570973 (102.495664) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:7147]: (style) The scope of the variable '_la' can be reduced.
102.570977 (102.495668) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:7680]: (style) The scope of the variable '_la' can be reduced.
102.570982 (102.495673) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:7759]: (style) The scope of the variable '_la' can be reduced.
102.570986 (102.495677) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:7938]: (style) The scope of the variable '_la' can be reduced.
102.570991 (102.495682) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:8126]: (style) The scope of the variable '_la' can be reduced.
102.570995 (102.495686) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:8220]: (style) The scope of the variable '_la' can be reduced.
102.571000 (102.495691) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:8313]: (style) The scope of the variable '_la' can be reduced.
102.571004 (102.495695) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:8491]: (style) The scope of the variable '_la' can be reduced.
102.571009 (102.495700) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:8703]: (style) The scope of the variable '_la' can be reduced.
102.571013 (102.495704) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:8783]: (style) The scope of the variable '_la' can be reduced.
102.571018 (102.495709) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:8914]: (style) The scope of the variable '_la' can be reduced.
102.571022 (102.495713) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:9119]: (style) The scope of the variable '_la' can be reduced.
102.571027 (102.495718) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:9220]: (style) The scope of the variable '_la' can be reduced.
102.571034 (102.495725) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:9414]: (style) The scope of the variable '_la' can be reduced.
102.571039 (102.495730) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:9660]: (style) The scope of the variable '_la' can be reduced.
102.571043 (102.495734) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10008]: (style) The scope of the variable '_la' can be reduced.
102.571048 (102.495739) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10158]: (style) The scope of the variable '_la' can be reduced.
102.571052 (102.495743) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10250]: (style) The scope of the variable '_la' can be reduced.
102.571057 (102.495748) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10370]: (style) The scope of the variable '_la' can be reduced.
102.571061 (102.495752) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10637]: (style) The scope of the variable '_la' can be reduced.
102.571065 (102.495756) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10749]: (style) The scope of the variable '_la' can be reduced.
102.571070 (102.495761) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10815]: (style) The scope of the variable '_la' can be reduced.
102.571075 (102.495766) E[1]: [src/query/frontend/opencypher/generated/CypherParser.cpp:10881]: (style) The scope of the variable '_la' can be reduced.
We know that we represented it correctly in memory:
102.571079 (102.495770) E[1]: [src/communication/bolt/v1/decoder/decoder.hpp:252]: (portability) Casting between integer* and double* which have an incompatible binary data representation.
Cont assigned but not used after:
102.571101 (102.495792) E[1]: [src/query/frontend/ast/ast.hpp:1008]: (style) Variable 'cont' is assigned a value that is never used.
Reviewers: teon.banek, buda, mferencevic
Reviewed By: teon.banek
Subscribers: mferencevic, pullbot
Differential Revision: https://phabricator.memgraph.io/D967
Summary: This reduces the size of a single `mvcc::Record<T>` from 40B to 24B.
Reviewers: buda, mislav.bradac, dgleich
Reviewed By: mislav.bradac, dgleich
Subscribers: mferencevic, pullbot
Differential Revision: https://phabricator.memgraph.io/D920
Summary: - modified all utils/algorithm functions to be inline and in the utils namespace
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D830
Summary:
- GC changed to evaluate old records w.r.t. the oldest transaction's id AND snapshot, as opposed to only id
- MVCC hints exp+aborted race condition prevented
- minor MVCC refactors and cleanups
- minor Transaction refactors and cleanups
Reviewers: buda, dgleich
Reviewed By: buda, dgleich
Subscribers: dtomicevic, pullbot
Differential Revision: https://phabricator.memgraph.io/D434
Summary:
Gradicek's Mvcc test have seen the following changes:
- provided a test infrastructure (fixture and macros) to facilitate testing and increase readability
- split tests into multi-transaction update, VersionList::find and general Mvcc testing
- multi-transaction update tests have been refactored (i *think* nothing got deleted, but it was a mess so I don't guarantee)
- changed all multithreaded tests to be single-threaded because multiple threads were not necessary
- changed transaction naming from T5, T8, T10 to T1, T2... for consistency with actual transaction indices
What still needs to be done:
- Gleich and Gradicek need to review the infrastructure (possible improvements)
- multi-transaction update tests need to be addressed by Gradicek (see "TODO gradicek" in code, discuss with Flor)
- the wiki/draw.io documentation needs to be updated. it is not imperative that all the tests be drawn in draw.io, only the general infrastructure explained. perhaps only a few examples drawn. Gradicek discuss with Flor
- Gleich see the "TODO Gleich" lines in the diff and discuss with flor
Suggested workflow:
- review this diff, hopefully land (before resolving all the TODOs)
- discard D169
- Gradicek and Gleich address the TODOs
- Flor reviews the results (in following diffs)
Reviewers: dgleich, matej.gradicek, buda
Reviewed By: matej.gradicek, buda
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D348
Summary:
The rest of core engine exceptions are extended from the BasicException (because of the error handling in the communication stack). Maximum value of the MVCC command id is calculated in the compile time.
I've put the tasks to implement concurrent tests in the qa repo in the backlog. Hopefully they will be implemented within this sprint.
Reviewers: mislav.bradac, mferencevic, florijan
Reviewed By: mislav.bradac
Subscribers: dgleich, pullbot, buda
Differential Revision: https://phabricator.memgraph.io/D298
Summary: Lock store was not locking properly. It created a lock object which was destructed in the end of function scope which caused bits to be set to UNLOCKED.
Reviewers: matej.gradicek, buda
Reviewed By: matej.gradicek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D154
Importes now use logger.
Refactored order of constrution of objects in Db.
Moved index creation/removing from Db to Indexes.
Completed Garbage class.
Cleaner now calls garbage.clean() for databases.
Renamed List to ConcurrentList which better names it.
Implemented untested UniqueOrderedIndex.
Introduced TypeGroupEdge/Vertex into database.
Added Index capabilityes to PropertyFamily.
Added method for adding index.
Added method for removing index.
