Package io.trino.plugin.accumulo.index

Class ColumnCardinalityCache

java.lang.Object
io.trino.plugin.accumulo.index.ColumnCardinalityCache
public class ColumnCardinalityCache extends Object
This class is an indexing utility to cache the cardinality of a column value for every table. Each table has its own cache that is independent of every other, and every column also has its own Guava cache. Use of this utility can have a significant impact for retrieving the cardinality of many columns, preventing unnecessary accesses to the metrics table in Accumulo for a cardinality that won't change much.

  • Constructor Details

    • ColumnCardinalityCache

      @Inject public ColumnCardinalityCache(org.apache.accumulo.core.client.Connector connector, AccumuloConfig config)

  • Method Details

    • shutdown

      @PreDestroy public void shutdown()

    • getCardinalities

      public com.google.common.collect.Multimap<Long,AccumuloColumnConstraint> getCardinalities(String schema, String table, org.apache.accumulo.core.security.Authorizations auths, com.google.common.collect.Multimap<AccumuloColumnConstraint,org.apache.accumulo.core.data.Range> idxConstraintRangePairs, long earlyReturnThreshold, io.airlift.units.Duration pollingDuration)
      Gets the cardinality for each AccumuloColumnConstraint. Given constraints are expected to be indexed! Who knows what would happen if they weren't!
      Parameters:
      schema - Schema name
      table - Table name
      auths - Scan authorizations
      idxConstraintRangePairs - Mapping of all ranges for a given constraint
      earlyReturnThreshold - Smallest acceptable cardinality to return early while other tasks complete
      pollingDuration - Duration for polling the cardinality completion service
      Returns:
      An immutable multimap of cardinality to column constraint, sorted by cardinality from smallest to largest

    • getColumnCardinality

      public long getColumnCardinality(String schema, String table, org.apache.accumulo.core.security.Authorizations auths, String family, String qualifier, Collection<org.apache.accumulo.core.data.Range> colValues) throws ExecutionException
      Gets the column cardinality for all of the given range values. May reach out to the metrics table in Accumulo to retrieve new cache elements.
      Parameters:
      schema - Table schema
      table - Table name
      auths - Scan authorizations
      family - Accumulo column family
      qualifier - Accumulo column qualifier
      colValues - All range values to summarize for the cardinality
      Returns:
      The cardinality of the column
      Throws:
      ExecutionException