madlib/madlib — pull request #289 by aojwang (2012-12-18 07:44:51+00:00)
Title: Compressed bitmap implementation.

JIRA: MADLIB-767
I implement the bitmap as a user defined type. The underlying storage is int4 array. The following functions are provided in this version:
1) aggregate: bitmap_agg
2) operators: |, &, ~ and #.
3) casts: int4[]/int8[] to bitmap, varbit to bitmap, bitmap to int4[] and bitmap to varbit.
4) functions: bitmap_set, bitmap_test, bitmap_nonzero_positions, bitmap_nonzero_count, and bitmap_unnest
5) comparator for btree operator class: >, <, >=, <=, =, <>.