Efficient hash table

A method, comprising:

• applying a hash function to values in an index column of a database table yielding hash values defining a plurality of buckets of a hash table;
• copying data from rows of the database table into the hash table as a plurality of tuples, each tuple including:
• a respective key from the index column of the database table;
• or the respective key from the index column of the database table and at least one value from a row of the database table including the respective key;
• arranging the plurality of tuples among the plurality of buckets in the hash table, a given bucket of the plurality of buckets including multiple tuples of the plurality of tuples;
• and
• storing the multiple tuples of the given bucket back-to-back in the hash table in memory without any pointer between the tuples to find at least one next tuple of the multiple tuples, wherein the storing the multiple tuples back-to-back in the hash table without pointers reduces memory usage compared to storing the tuples with pointers.

A software product, comprising a non-transient computer-readable medium in which program instructions are stored, which instructions, when read by a central processing unit (CPU), cause the CPU to:

• apply a hash function to values in an index column of a database table yielding hash values defining a plurality of buckets of a hash table;
• copy data from rows of the database table into the hash table as a plurality of tuples, each tuple including:
• a respective key from the index column of the database table;
• or the respective key from the index column of the database table and at least one value from a row of the database table including the respective key;
• arrange the plurality of tuples among the plurality of buckets in the hash table, a given bucket of the plurality of buckets including multiple tuples of the plurality of tuples;
• and
• store the multiple tuples of the given bucket back-to-back in the hash table in memory without any pointer between the tuples to find at least one next tuple of the multiple tuples, wherein the storing the multiple tuples back-to-back in the hash table without pointers reduces memory usage compared to storing the tuples with pointers.