HiLang 2.5.28

• .NETStandard 2.0

  • FSharp.Core (>= 10.0.100)
  • FsLexYacc (>= 11.3.0)
  • FsLexYacc.Runtime (>= 11.3.0)
  • Microsoft.CodeAnalysis.CSharp (>= 5.0.0)

https://www.cepheis.com/hiperspace/20251231
# Overview
Change to the `GetSequence` and `UseSequence` functions to take a parameter to allow the use of `KeyType` for Sequences

Extended  `Session2(DateTime? AsAt = null)`  to `Session2(DateTime? AsAt = null, DateTime? DeltaFrom = null)` to allow the DeltaFrom parameter to be used in addition to AsAt.
## Obsolete
Several interfaces function have been marked as `Obsolete` and will be removed in the next version.

Currently **Hiperspace** uses a key prefix convention to distinguish *immutable* and *versioned* elements, *VectorSpaces* (for nearest neighbor search) and *sequences*

| Prefix | Description |
|-|-|
| 00| The meta data dictionary for the *Hiperspace*, used to ensure that incompatible libraries cannot corrupt a store |
| 0...| Versioned element that includes a *timestamp* suffix at the end of the key |
| 00...| VectorSpace indexes|
| 001...|  Sequence numbers for mutable items|
| |Keys without a prefix are immutable elements without version|

Performance testing of **Hiperspace.DB**  has highlighted that the rebuilding of the `MetaMap` used to translate between protobuf *tag/length/value* to *tag/value/length* for index search can be expensive top build when a store has experienced multiple schema changes.  The **next** version will change the prefix to:

| Prefix | Description |
|-|-|
|1| The meta data dictionary for the *Hiperspace*, used to ensure that incompatible libraries cannot corrupt a store |
|2| cached `MetaMap` entries for key encode/decode|
|3| validated client library *fingerprint* to avoid the need for `MetaMap` build |
|4| immutable elements without version suffix|
|5| Versioned element that includes a *timestamp* suffix at the end of the key |
|6| VectorSpace indexes|
|7|  Sequence numbers for mutable items|

The `#id` for {`Node`, `Edge`, `VectorNode`, `HiperEdge`,`PathMessage`} will also be moved to a *reserved* set of low values with all *domain* keys moved to higher values

-----

## SetSpace
Added two functions to get a sequence counter from the driver:
* `GetSequenceAsync<T>(T element)` to get the current sequence number associated with the domain key
* `UseSequenceAsync<T>(T element)` to get a new  sequence number for the with the domain key

**NB** While the main use of Sequence numbers is to provide an alternate (*GPGPU friendly*) sequence number for a `Node`, it can be applied to any key value.
```
// get an order number that is unique within all orders
var orderNo = await space.Orders.UseSequenceAsync (new Order { });
var orderNo = await space.Orders.UseSequenceAsync (new Order.KeyType { });

// get a line number within the owning Order {1,2,3..}
var lineNo = await space.Lines.UseSequenceAsync (new Line { Order = order });
var lineNo = await space.Lines.UseSequenceAsync (new Line.KeyType { Order = order.self });
```

`Get` and `GetASync()` functions now handle not found errors by returning `null` for scenarios where a reference object cannot be found.  This is especially useful for views where not found is better handled by `Horizon<>` filters that

-----

## Bind Version
All versions of Bind Function have been marked as Obsolete, with a preference to use the optimistic locking instead (that include the original AsAt copied to AsWas for comparison).
Versions of Bind functions that include the `priorVersion` DateTime value use optimistic concurrency control to prevent updates to a version that has been changed by another session

## Nearest
Hiperspace provides nearest neighbor search using a VectorSpace `aspect` for geospatial and RAG search.  These functions have been extended to include a maximum distance search

-----

## Hilang
The Hilang ahead of time compiler has been updated to remove indexes that are a subset of the element key, and will not be used


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## Hiperspace.Rocks
The **RocksDB** driver has been upgraded to verion 10.4.2.63147