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MDEV-28846 Poor performance when rowid filter contains no elements

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When a range rowid filter was used with an index ref access the cost of
accessing the index entries for the records rejected by the filter was not
taken into account. For a ref access by an index with big average number
of records per key this led to poor execution plans if selectivity of the
used filter was high.
The patch resolves this problem. It also introduces a minor optimization
that skips look-ups into a filter that turns out to be empty.
With this patch the output of ANALYZE stmt reports the number of look-ups
into used rowid filters.
The patch also back-ports from 10.5 the code that properly sets the field
TABLE::file::table for opened temporary tables.

The test cases that were supposed to use rowid filters have been adjusted
in order to use similar execution plans after this fix.

Approved by Oleksandr Byelkin <sanja@mariadb.com>
This commit is contained in:
Igor Babaev
2022-10-17 16:44:10 -07:00
parent f1bbc1cd19
commit 58cd0bd59e
21 changed files with 1797 additions and 170 deletions
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6
sql/handler.h
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@ -3156,6 +3156,11 @@ public:
DBUG_ASSERT(m_lock_type == F_UNLCK);
DBUG_ASSERT(inited == NONE);
}
/* To check if table has been properely opened */
bool is_open()
{
return ref != 0;
}
virtual handler *clone(const char *name, MEM_ROOT *mem_root);
/** This is called after create to allow us to set up cached variables */
void init()
@ -4804,6 +4809,7 @@ public:
ha_share= arg_ha_share;
return false;
}
void set_table(TABLE* table_arg) { table= table_arg; }
int get_lock_type() const { return m_lock_type; }
public:
/* XXX to be removed, see ha_partition::partition_ht() */