This is a subtask of MCOL-4525 Implement select_handler=AUTO.
Server performs outer join to inner join conversion using simplify_joins()
in sql/sql_select.cc, by updating the TABLE_LIST::outer_join variable.
In order to perform this conversion, permanent changes are made in some
cases to the SELECT_LEX::JOIN::conds and/or TABLE_LIST::on_expr.
This is undesirable for MCOL-4525 which will attemp to fallback and execute
the query inside the server, in case the query execution fails in ColumnStore
using the select_handler.
For a query such as:
SELECT * FROM t1 LEFT JOIN t2 ON expr1 LEFT JOIN t3 ON expr2
In some cases, server can update the original SELECT_LEX::JOIN::conds
and/or TABLE_LIST::on_expr and create new Item_cond_and objects
(e.g. with 2 Item's expr1 and expr2 in Item_cond_and::list).
Instead of making changes to the original query structs, we use
gp_walk_info::tableOnExprList and gp_walk_info::condList. 2 Item's,
expr1 and expr2, in the condList, mean Item_cond_and(expr1, expr2), and
hence avoid permanent transformations to the SELECT_LEX.
We also define a new member variable
ha_columnstore_select_handler::tableOuterJoinMap
which saves the original TABLE_LIST::outer_join values before they are
updated. This member variable will be used later on to restore to the original
state of TABLE_LIST::outer_join in case of a query fallback to server execution.
The original simplify_joins() implementation in the server also performs a
flattening of the JOIN nest, however we don't perform this operation in
convertOuterJoinToInnerJoin() since it is not required for ColumnStore.
InSub::handleFunc() was incorrectly exiting early for an IN subquery
containing an isnull predicate in the OR operation in the WHERE clause.
This patch properly handles the OR predicate containing an isnull/isnotnull
predicate in the WHERE clause. We don't remove the isnull operand from the
filter ParseTree in 6.x as the server no longer injects the isnull predicate
in the IN subquery due to MCOL-4617, where we moved the creation and injection
of in-to-exists predicate into the engine.
mcsconfig.h and my_config.h have the following
pre-processor definitions:
1. Conflicting definitions coming from the standard cmake definitions:
- PACKAGE
- PACKAGE_BUGREPORT
- PACKAGE_NAME
- PACKAGE_STRING
- PACKAGE_TARNAME
- PACKAGE_VERSION
- VERSION
2. Conflicting definitions of other kinds:
- HAVE_STRTOLL - this is a dirt in MariaDB headers.
Should be fixed in the server code. my_config.h erroneously
performs "#define HAVE_STRTOLL" instead of "#define HAVE_STRTOLL 1".
in some cases. The former is not CMake compatible style. The latter is.
3. Non-conflicting definitions:
Otherwise, mcsconfig.h and my_config.h should be mutually compatible,
because both are generated by cmake on the same host machine. So
they should have exactly equal definitions like "HAVE_XXX", "SIZEOF_XXX", etc.
Observations:
- It's OK to include both mcsconfig.h and my_config.h providing that we
suppress duplicate definition of the above conflicting types #1 and #2.
- There is no a need to suppress duplicate definitions mentioned in #3,
as they are compatible!
- my_sys.h and m_ctype.h must always follow a CMake configuation header,
either my_config.h or mcsconfig.h (or both).
They must never be included without any preceeding configuration header.
This change make sure that we resolve conflicts by:
- either disallowing inclusion of mcsconfig.h and my_config.h
at the same time
- or by hiding conflicting definitions #1 and #2
(with their later restoring).
- also, by making sure that my_sys.h and m_ctype.h always follow
a CMake configuration file.
Details:
- idb_mysql.h can now only be included only after my_config.h
An attempt to use idb_mysql.h with mcsconfig.h instead of
my_config.h is caught by the "#error" preprocessor directive.
- mariadb_my_sys.h can now be only included after mcsconfig.h.
An attempt to use mariadb_my_sys.h without mcscofig.h
(e.g. with my_config.h) is also caught by "#error".
- collation.h now can now be included in two ways.
It now has the following effective structure:
#if defined(PREFER_MY_CONFIG_H) && defined(MY_CONFIG_H)
// Remember current conflicting definitions on the preprocessor stack
// Undefine current conflicting definitions
#endif
#include "mcsconfig.h"
#include "m_ctype.h"
#if defined(PREFER_MY_CONFIG_H) && defined(MY_CONFIG_H)
# Restore conflicting definitions from the preprocessor stack
#endif
and can be included as follows:
a. using only mcsconfig.h as a configuration header:
// my_config.h must not be included so far
#include "collation.h"
b. using my_config.h as the first included configuration file:
#define PREFER_MY_CONFIG_H // Force conflict resolution
#include "my_config.h" // can be included directly or indirectly
...
#include "collation.h"
Other changes:
- Adding helper header files
utils/common/mcsconfig_conflicting_defs_remember.h
utils/common/mcsconfig_conflicting_defs_restore.h
utils/common/mcsconfig_conflicting_defs_undef.h
to perform conflict resolution easier.
- Removing `#include "collation.h"` from a number of files,
as it's automatically included from rowgroup.h.
- Removing redundant `#include "utils_utf8.h"`.
This change is not directly related to the problem being fixed,
but it's nice to remove redundant directives for both collation.h
and utils_utf8.h from all the files that do not really need them.
(this change could probably have gone as a separate commit)
- Changing my_init() to MY_INIT(argv[0]) in the MCS services sources.
After the fix of the complitation failure it appeared that ColumnStore
services compiled with the debug build crash due to recent changes in
safemalloc. The crash happened in strcmp() with `my_progname` as an argument
(where my_progname is a mysys global variable). This problem should
probably be fixed on the server side as well to avoid passing NULL.
But, the majority of MariaDB executable programs also use MY_INIT(argv[0])
rather than my_init(). So let's make MCS do like the other programs do.
in the query projection list.
With this patch, we enable SELECT/DERIVED handler execution for
queries involving 'get_user_var' function. Whereas for 'set_user_var'
function, the handlers are still disabled and the query execution
fallsback to the server, except for some edges case described in
the test file mcol-4410.test, in which case, an appropriate error
message is returned to the client.
Main theme of the patch is to fix joins processing in the plugin
code. We now use SELECT_LEX::top_join_list and process the nested
joins recursively, instead of SELECT_LEX::table_list struct which
we earlier used to build the join filters. The earlier approach
did not process certain nested join ON expressions, causing certain
queries to incorrectly error out such as that described in MCOL-4680.
In addition, some legacy code is also removed.
We earlier leveraged the server functionality provided by
Item_in_subselect::create_in_to_exists_cond and
Item_in_subselect::inject_in_to_exists_cond
to create and inject the in-to-exists predicate into an IN
subquery's JOIN struct. With this patch, we leave the IN subquery's
JOIN unaltered and instead directly perform this predicate creation
and injection into ColumnStore's select execution plan.
For a query of the form:
SELECT COUNT(c2) FROM (SELECT * FROM t1) q;
where t1 contains 10 columns c1, c2, ... , c10.
We currently create an intermediate RowGroup in ExeMgr with
a row of the form (1, c2_value1, 1, 1, 1, 1, 1, 1, 1, 1), i.e.
for all the columns of the subquery which are not referenced in
the outer query, we substitute a constant value, which is wasteful.
With this optimization, we are trimming the RowGroup to a row
of the form (1, c2_value1). This can have non-trivial query
execution time improvements if the subquery contains large number
of columns (such as a "select *" on a very wide table) and the outer
query is only referencing a subset of these columns with lower
index values from the subquery (as an example, c1 or c2 above).
That is, the current limitation of this optimization is we are not
removing those non-referenced subquery columns (c1 in the query above)
which are to the left of a referenced column.
After the cleanup work done for FETCH FIRST ... WITH TIES
SELECT_LEX members select_limit, explicit_limit and offset_limit are now moved
to SELECT_LEX::limit_params.
type is not LEFT/RIGHT.
In buildOuterJoin(), do not add ON expressions for WHERE
processing when the JOIN type is not LEFT/RIGHT.
Test cases to check correct processing of INNER JOIN ON expressions
with possible/impossible WHERE conditions are added for
1. One side of the LEFT JOIN being INNER JOIN.
2. One side of the LEFT JOIN being an INNER JOIN inside an INNER JOIN.
3. Both sides of the LEFT JOIN being an INNER JOIN.
An INSERT .. SELECT performed on a master node caused an infinite
loop on the slave node with columnstore_replication_slave=OFF.
The issue was ha_mcs_impl_select_next() was returning 0 if
the executing thread is a slave and returning early to avoid DML
execution on the slave. The calling code in select_handler::execute()
ran into an infinite loop due to this as it checked the return code
of the function as 0, and incorrectly thought there are more rows
to process.
The fix is to return HA_ERR_END_OF_FILE as the return value,
instead of 0. This is for the case of the query running on the
slave node with columnstore_replication_slave=OFF.
For TIMESTAMP, it should do similar. However, it didn't work. For some reason, MDB has the function set as DATETIME, which for cs, isn't the same thing. Added a kludge to ha_mcs_execplan.cpp to handle it.
1. This patch adds support for wide decimals with/without scale
to cpimport. In addition, INSERT ... SELECT and LDI are also
now supported.
2. Logic to compute the number of bytes to convert a binary
representation in the buffer to a narrow decimal is also
simplified.
for a generated replacement statements of original statements:
* `CREATE TABLE .. LIKE ..`
* `ALTER TABLE .. ENGINE=Columnstore`
* `CREATE TABLE .. AS ..`
MCOL-2000 Process charset definitions in the ALTER TABLE .. ADD COLUMN
MCOL-2000 Yet another fixes for column charsets
* make respect for column (including table/db/server default) charsets
for the TEXT(n) fields
* round TEXT(n) column length up to the next default length of TEXT-like
subtypes, 255 (TINYTEXT), 65535 (TEXT) and so on up to 2100000000
(LONGTEXT)
1. Add wide decimal support to AggregateColumn::evaluate
and TreeNode::getDecimalVal().
2. Use the pm aggregate attributes to determine um aggregate
attributes in TupleAggregateStep::prep2PhasesAggregate.
MCOL-4409 This patch combines VDecimal and Decimal and makes
IDB_Decimal an alias for the result class
MCOL-4409 More boilerplate reduction in Func_mod
Removed couple TSInt128::toType() methods
- The code in ha_mcs_partition.cpp erroneously printed data
to a temporary ostringstream "oss" instead of "output".
- The left-side adjustfield (applied when printing the range values)
unintentionally disappeared during MCOL-4174 refactoring.
Restoring left adjustfield in TypeHandler::PrintPartitionValue*().
For now it consists of only:
using int128_t = __int128;
using uint128_t = unsigned __int128;
All new privitive data types should go into this file in the future.
1. Perform type promotion to wide decimal if the result
of an arithmetic operation has a precision > 18.
2. Only set the decimal width of an arithmetic operation to wide
if both the LHS and RHS of the operation are decimal types.
