major change
change data format of binary dict page, appending (dict page data) and (dict page offset) to binary dict page;
add new decoding method for new binary dict page format
add ut for segment test
set the elements of initial array to 0 ,when calling arena.AllocateNewBlock
hard code way to choose dict coding for string
0919 commit major change
change dict file format:when saving binary dict page, separate dict page from dict page,one dict page may have multi data pages;when reading a binary dict page,one ColumnReader keeps one dict page
loading dict when calling column_reader._read_page
3.rollback BinaryDictPage
no longer using memset(0) to inital column_zonemap.max_value
0926 17 commit major change
init column_zone_map min value column_zone_map slice's data array;
set char/varchar column_zone_map'max value size to 0
add ut for char column zone map query hit/miss
0929 10 commit major change
allocate mem for column_zone_map 's max and min value
direct copy content to column_zone_map's max and min value
8aa8e08f27