- Describe the lifetime of EXPLAIN data structures in
sql_explain.h:ExplainDataStructureLifetime.
- Make Item_field::set_field() call set_refers_to_temp_table()
when it refers to a temp. table.
- Introduce QT_DONT_ACCESS_TMP_TABLES flag for Item::print.
It directs Item_field::print to not try access its the
temp table.
- Introduce Explain_query::notify_tables_are_closed()
and call it right before the query closes its tables.
- Make Explain data stuctures' print_explain_json() methods
accept "no_tmp_tbl" parameter which means pass
QT_DONT_ACCESS_TMP_TABLES when printing items.
- Make Show_explain_request::call_in_target_thread() not call
set_current_thd(). This wasn't needed as the code inside
lex->print_explain() uses output->thd anyway. output->thd
refers to the SHOW command's THD object.
1. Add explicit indication that the output is produced by
SHOW EXPLAIN/ANALYZE FORMAT=JSON command.
2. Remove useless "r_total_time_ms" field from SHOW ANALYZE FORMAT=JSON
output when there is no timed statistics gathered.
3. Add "r_query_time_in_progress_ms" to the output of SHOW ANALYZE FORMAT=JSON.
EXPLAIN FOR CONNECTION is a MySQL-compatible syntax for SHOW EXPLAIN.
This commit also adds support for FORMAT=JSON to SHOW EXPLAIN,
so the possible options to get JSON-formatted output are:
- SHOW EXPLAIN FORMAT=JSON FOR $con
- EXPLAIN FORMAT=JSON FOR CONNECTION $con
As agreed with Serg, renaming class Yesno to Yes_or_empty,
to reflect better its behavior.
This helper class is used to define INFORMATION_SCHEMA columns
that return either "Yes" or an empty string.
Analysis: There are 2 server variables- "old_mode" and "old". "old" is no
longer needed as "old_mode" has replaced it (however still used in some places
in the code). "old_mode" and "old" has same purpose- emulate behavior from
previous MariaDB versions. So they can be merged to avoid confusion.
Fix: Deprecate "old" variable and create another mode for @@old_mode to mimic
behavior of previous "old" variable. Create specific modes for specifix task
that --old sql variable was doing earlier and use the new modes instead.
`m_status == DA_ERROR' failed on SELECT after setting tmp_disk_table_size.
Analysis: Mismatch in number of warnings between "194 warnings" vs
"64 rows in set" is because of max_error_count variable which has default
value of 64.
About the corrupted tables, the error that occurs because of insufficient
tmp_disk_table_size variable is not reported correctly and we continue to
execute the statement. But because the previous error (about table being
full)is not reported correctly, this error moves up the stack and is
wrongly reported as parsing error later on while parsing frm file of one
of the information schema table. This parsing error gives corrupted table
error.
As for the innodb error, it occurs even when tmp_disk_table_size is not
insufficient is default but the internal error handler takes care of it
and the error doesn't show. But when tmp_disk_table_size is insufficient,
the fatal error which wasn't reported correctly moves up the stack so
internal error handler is not called. So it shows errors.
Fix: Report the error correctly.
Problem:
DECIMAL columns in I_S must be explicitly set of some value.
I_S columns do not have `DEFAULT 0` (after MDEV-18918), so during
restore_record() their record fragments pointed by Field::ptr are
initialized to zero bytes 0x00.
But an array of 0x00's is not a valid binary DECIMAL value.
So val_decimal() called for such Field_new_decimal generated a warning
when seeing a wrong binary encoded DECIMAL value in the record.
Fix:
Explicitly setting INFORMATION_SCHEMA.PROCESSLIST.PROGRESS
to the decimal value of 0 if no progress information is available.
