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Slice Index

A slice index groups nodes in a sorted list based on a specific value

TypeScript
new Garak.SliceIndex(
  "name",
  Store,
  {
    groupOn: string,
    indexOn: string,

  }
);

Name​

A unique name for the slice, identifying it in the database. No two slice indexes may have the same name across the silo, regardless of store.

Group on​

Slice indexes are sorted into groups, groups will be determined by the value of the groupOn field (similar to a categorization index). To form a universal group across the silo, "$" may be provided.

Index on​

The field to sort the slice and query from. This may be any scalar, and will be converted to a number internally for querying.

Number => remains the same
Boolean => 0 for false and 1 for true
String => Converted to number using fnv1a64
String Conversion

Due to the fact fnv1a64 is used to convert strings for slices, alphabetical order is NOT guaranteed.

Include​

Optionally, an include option may be specified, limiting which nodes get included in the categorization:

TypeScript
new Garak.SliceIndex(
  "name",
  Store,
  {
    groupOn: string,
    indexOn: string,
    include: {
      "status": {
        $eq: "active"
      }
    }
  }
);

Nodes will only be added to the slice if the include selector resolves to true. If a node originally had the include selector match, but has an update that results in the selector no longer matching, it will be removed from the index.

Querying​

Three methods can be used to query a slice. Note that for group, if your index is set to group on all you may pass "$" here.

Query from a starting point​

const mySlice = ...;

mySlice.before(tx, group, before, limit);
mySlice.after(tx, group, after, limit);

Note that after/before are inclusive, so querying after: 30 will return nodes where the value is 30. The name can be a bit deceptive, but think of after as >= and before as <=.

Query a range​

const mySlice = ...;

mySlice.until(tx, group, from, to);

When querying a range, note that a theoretically unlimited number of nodes can be returned. Be careful with your ranges.

Working with a query handle:​

const myHandle = mySlice.before(...); // or mySlice.after(...) or mySlice.until(...)

await myHandle.lookup(); // { nodes: number[] }
await myHandle.fetch(); // Array<{ node_id: number, value: T | null }>