The code in create_internal_tmp_table() didn't take into account that
now temporary (derived) tables may have multiple indexes:
- one index due to duplicate removal
= In this example created by conversion of big-IN(...) into subquery
= this index might be converted into a "unique constraint" if the key
length is too large.
- one index added by derived_with_keys optimization.
Make create_internal_tmp_table() handle multiple indexes.
Before this patch, use of a unique constraint was indicated in
TABLE_SHARE::uniques. This was ok as unique constraint was the only index
in the table. Now it's no longer the case so TABLE_SHARE::uniques is removed
and replaced with an in-memory-only flag HA_UNIQUE_HASH.
This patch is based on Monty's patch.
Co-Author: Monty <monty@mariadb.org>
The problem, introduced in patch for MDEV-26301:
When check_join_cache_usage() decides not to use join buffer, it must
adjust the access method accordingly. For BNL-H joins this means switching
from pseudo-"ref access"(with index=MAX_KEY) to some other access method.
Failing to do this will cause assertions down the line when code that is
not aware of BNL-H will try to initialize index use for ref access with
index=MAX_KEY.
The fix is to follow the regular code path to disable the join buffer for
the join_tab ("goto no_join_cache") instead of just returning from
check_join_cache_usage().
Introduces @@optimizer_switch flag: hash_join_cardinality
When this option is on, use EITS statistics to produce tighter bounds
for hash join output cardinality.
This patch is an extension / replacement to a similar patch in 10.6
New features:
- optimizer_switch hash_join_cardinality is on by default
- records_out is set to fanout when HASH is used
- Fixed bug in is_eits_usable: The function did not work with views
This patch optimizes the number of refills for the lateral derived table
to which a materialized derived table subject to split optimization is
is converted. This optimized number of refills is now considered as the
expected number of refills of the materialized derived table when searching
for the best possible splitting of the table.
When processing a query over a mergeable view at some conditions checked
at prepare stage it may be decided to materialize the view rather than
to merge it. Before this patch in such case the field 'derived' of the
TABLE_LIST structure created for the view remained set to 0. As a result
the guard condition preventing range analysis for materialized views did
not work properly. This led to a call of some handler method for the
temporary table created to contain the view's records that was supposed
to be used only for opened tables. However temporary tables created for
materialization of derived tables or views are not opened yet when range
analysis is performed.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
Introduce @@optimizer_switch flag: hash_join_cardinality
When it is on, use EITS statistics to produce tighter bounds for
hash join output cardinality.
Amended by Monty.
Reviewed by: Monty <monty@mariadb.org>
Fix-up for commit 476b24d084
Author: Monty
Date: Thu Feb 16 14:19:33 2023 +0200
MDEV-20057 Distinct SUM on CROSS JOIN and grouped returns wrong result
which misses initializing of sorder->suffix_length.
In this commit the initialization is implemented by passing
MY_ZEROFILL flag to the allocation of SORT_FIELD elements
Now the same rule applied to vews and derived tables. So we should
allow merge of views (and derived) in queries with rownum, because
it do not change results, only makes query plans better.
Rewrite datetime comparison conditions into sargeable. For example,
YEAR(col) <= val -> col <= YEAR_END(val)
YEAR(col) < val -> col < YEAR_START(val)
YEAR(col) >= val -> col >= YEAR_START(val)
YEAR(col) > val -> col > YEAR_END(val)
YEAR(col) = val -> col BETWEEN YEAR_START(val) AND YEAR_END(val)
Do the same with DATE(col), for example:
DATE(col) <= val -> col <= DAY_END(val)
After such a rewrite index lookup on column "col" can be employed
This bug caused server crash when processing a multi-update statement that
used views if optimizer tracing was enabled.
The bug was introduced in the patch for MDEV-30539 that could incorrectly
detect the most top level selects of queries if views were used in them.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
After MDEV-30830 has added block-nl-join.r_unpack_time_ms, it became
apparent that there is some unaccounted-for time in BNL join operation,
namely the time that is spent after unpacking the join buffer record.
Fix this by adding a Gap_time_tracker to track the time that is spent
after unpacking the join buffer record and before any next time tracking.
The collected time is printed in block-nl-join.r_other_time_ms.
Reviewed by: Monty <monty@mariadb.org>
