HashMapGenerator¶

HashMapGenerator is an abstraction of HashMap generators that can generate an append-only row-based hash map for extremely fast key-value lookups while evaluating aggregates.

Contract¶

generateEquals¶

generateEquals(): String

Used when:

• HashMapGenerator is requested to generate a Java code

generateFindOrInsert¶

generateFindOrInsert(): String

Used when:

• HashMapGenerator is requested to generate a Java code

generateRowIterator¶

generateRowIterator(): String

Used when:

• HashMapGenerator is requested to generate a Java code

initializeAggregateHashMap¶

initializeAggregateHashMap(): String

Used when:

• HashMapGenerator is requested to generate a Java code

Implementations¶

• RowBasedHashMapGenerator
• VectorizedHashMapGenerator

Generating Java Code¶

generate(): String

generate creates a source code of a Java class with the following (in that order):

1. generatedClassName
2. initializeAggregateHashMap
3. generateFindOrInsert
4. generateEquals
5. generateHashFunction
6. generateRowIterator
7. generateClose

generate is used when:

• HashAggregateExec physical operator is requested to doProduceWithKeys