Package io.deephaven.engine.table

Interface DataIndex.RowKeyLookup

Enclosing interface:
DataIndex
public static interface DataIndex.RowKeyLookup
Provides a lookup function from a lookup key to the row key in the index table. Lookup keys consist of reinterpreted values and are specified as follows:
No key columns
"Empty" keys are signified by any zero-length Object[], and are looked up one at a time; the chunked apply needs a key column to give the number of keys
One key column
Singular keys are (boxed, if needed) objects
Multiple key columns
Compound keys are Object[] of (boxed, if needed) objects, in the order of the index's key columns

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    apply(@NotNull Chunk<? extends Values>[] keyChunks, @NotNull WritableLongChunk<RowKeys> rowKeys, boolean usePrev)
    Get the row key in the index table for each of a chunk of lookup keys, given one chunk per key column in the order of the index's key columns, each reinterpreted as for apply(Object, boolean).
    long
    apply(Object key, boolean usePrev)
    Get the row key in the index table for the provided lookup key.
    default long
    lastStateChangeStep()
    The step on which the index last began changing the structure its lookups read, recorded before the change, or QueryConstants.NULL_LONG if it never changes.

  • Method Details

    • apply

      long apply(Object key, boolean usePrev)
      Get the row key in the index table for the provided lookup key.
      Parameters:
      key - The key to lookup
      Returns:
      The result row key, or RowSequence.NULL_ROW_KEY if the key is not found.

    • apply

      void apply(@NotNull @NotNull Chunk<? extends Values>[] keyChunks, @NotNull @NotNull WritableLongChunk<RowKeys> rowKeys, boolean usePrev)
      Get the row key in the index table for each of a chunk of lookup keys, given one chunk per key column in the order of the index's key columns, each reinterpreted as for apply(Object, boolean). The index must have at least one key column, whose chunk gives the number of keys.

      Implementations that cannot search a chunk of keys at once may delegate to io.deephaven.engine.table.impl.dataindex.DataIndexUtils.lookupRowKeysBoxed, which boxes each key and calls apply(Object, boolean).

      Parameters:
      keyChunks - The lookup keys, one chunk per key column, at least one, all the same size
      rowKeys - Receives the result row key of each lookup key, or RowSequence.NULL_ROW_KEY for a key that is not found; its size is set to the number of keys
      usePrev - Whether to look up the keys in previous space

    • lastStateChangeStep

      default long lastStateChangeStep()
      The step on which the index last began changing the structure its lookups read, recorded before the change, or QueryConstants.NULL_LONG if it never changes. Calling this orders the lookups made before it ahead of reading the step.

      A refreshing index may change that structure while a reader that is not on the update graph thread uses it. Such a reader reads its step from the update graph's clock before its lookups, and this after them. Compared to the reader's step, this is:

      • less: the lookups answered for the index's state at the reader's step, previous and current alike;
      • equal: the lookups may not have answered for the previous state, and answered for the current state if the reader waited for the index to be satisfied at its step;
      • greater: the lookups may not have answered for either state at the reader's step.
      Returns:
      The step on which the index last began changing the structure its lookups read