This simplifies the code and the access to the min/max
metadata. Before we used a custom type, but now the min/max
are just the same type as the underlying column and stored as two
columns.
This also removes the custom type that was used before.
- Fix declaration of functions wrt TSDLLEXPORT consistency
- Empty structs need to be created with '{ 0 }' syntax.
- Alignment sentinels have to use uint64 instead of a struct
with a 0-size member
- Add some more ORDER BY clauses in the tests to constrain
the order of results
- Add ANALYZE after running compression in
transparent-decompression test
This commit pushes down quals or order_by columns to make
use of the SegmentMetaMinMax objects. Namely =,<,<=,>,>= quals
can now be pushed down.
We also remove filters from decompress node for quals that
have been pushed down and don't need a recheck.
This commit also changes tests to add more segment by and
order-by columns.
Finally, we rename segment meta accessor functions to be smaller
Add a sequence id to the compressed table. This id increments
monotonically for each compressed row in a way that follows
the order by clause. We leave gaps to allow for the
possibility to fill in rows due to e.g. inserts down
the line.
The sequence id is global to the entire chunk and does not reset
for each segment-by-group-change since this has the potential
to allow some micro optimizations when ordering by a segment by
columns as well.
The sequence number is a INT32, which allows up to 200 billion
uncompressed rows per chunk to be supported (assuming 1000 rows
per compressed row and a gap of 10). Overflow is checked in the
code and will error if this is breached.
This commit integrates the SegmentMetaMinMax into the
compression logic. It adds metadata columns to the compressed table
and correctly sets it upon compression.
We also fix several errors with datum detoasting in SegmentMetaMinMax
This patch adds a DecompressChunk custom scan node, which will be
used when querying hypertables with compressed chunks to transparently
decompress chunks.
This is useful, if some or all compressed columns are NULL.
The count reflects the number of uncompressed rows that are
in the compressed row. Stored as a 32-bit integer.
Add support for compress_chunks function.
This also adds support for compress_orderby and compress_segmentby
parameters in ALTER TABLE. These parameteres are used by the
compress_chunks function.
The parsing code will most likely be changed to use PG raw_parser
function.
