When an outer query filter accesses an subquery column that contains an aggregate or a window function, certain optimizations can't be performed. We had been looking at the surface of the returned column. We now iterate into any functions or operations looking for aggregates and window functions.
column width
RTSCommand was modified to use a fabric that produces CC class based on column width
NB this patch doesn't affect PseudoCC that also leverages ColumnCommand
1. Add a new system variable, columnstore_use_cpimport_for_cache_inserts,
that when set to ON, uses cpimport for the cache flush into ColumnStore.
This variable is set to OFF by default. By default, we perform batch inserts
for the cache flush.
2. Disable DMLProc logging of the SQL statement text for the cache
flush operation in case of batch inserts. Under certain heavy loads
involving INSERT statements, this logging becomes a bottleneck for
the cache flush, causing subsequent inserts into the cache table to hang.
* Adds CompressInterfaceLZ4 which uses LZ4 API for compress/uncompress.
* Adds CMake machinery to search LZ4 on running host.
* All methods which use static data and do not modify any internal data - become `static`,
so we can use them without creation of the specific object. This is possible, because
the header specification has not been modified. We still use 2 sections in header, first
one with file meta data, the second one with pointers for compressed chunks.
* Methods `compress`, `uncompress`, `maxCompressedSize`, `getUncompressedSize` - become
pure virtual, so we can override them for the other compression algos.
* Adds method `getChunkMagicNumber`, so we can verify chunk magic number
for each compression algo.
* Renames "s/IDBCompressInterface/CompressInterface/g" according to requirement.
For queries of the form:
SELECT col1 FROM t1 WHERE col2 = (SELECT 2);
We fix the execution plan which earlier had an empty filters
expression. For this query, we now build a SimpleFilter with a
SimpleColumn and a ConstantColumn as the LHS and the RHS operands
respectively.
For queries of the form:
SELECT ... WHERE col1 NOT IN (SELECT <const_item>);
The execution plan earlier built a SimpleFilter with an "=" as
the predicate operator of the filter. We fix this by assigning
the correct "<>" operator instead.
cross-engine join with a ColumnStore table errors out.
ColumnStore cannot directly update a foreign table. We detect whether
a multi-table UPDATE operation is performed on a foreign table, if so,
do not create the select_handler and let the server execute the UPDATE
operation instead.
