Fixes#2892
IMPORTANT NOTICE: this CL makes incompatible changes to V2 storage format, developers need to create new tables for test.
This CL refactors the metadata and page format for segment_v2 in order to
* make it easy to extend existing page type
* make it easy to add new page type while not sacrificing code reuse
* make it possible to use SIMD to speed up page decoding
Here we summary the main code changes
* Page and index metadata is redesigned, please see `segment_v2.proto`
* The new class `PageIO` is the single place for reading and writing all pages. This removes lots of duplicated code. `PageCompressor` and `PageDecompressor` are now useless and removed.
* The type of value ordinal is changed from `rowid_t` to 64-bits `ordinal_t`, this affects ordinal index as well.
* Column's ordinal index is now implemented by IndexPage, the same with IndexedColumn.
* Zone map index is now implemented by IndexedColumn
After replacing Arena with MemPool, we can achieve one copy for string
value read from segment v2. We can exchange MemPool's chunk between
RowBlockV2 and RowBlock. This change only replace Arena, this work will
be done in other change list.
We create a new segment format for BetaRowset. New format merge
data file and index file into one file. And we create a new format
for short key index. In origin code index is stored in format like
RowCusor which is not efficient to compare. Now we encode multiple
column into binary, and we assure that this binary is sorted same
with the key columns.
