UPDATE gets access to history records because versioning conditions
are not set for VIEW. This leads to endless loop of inserting history
records when clustered index is rebuilt and ha_rnd_next() returns
newly inserted history record.
Return back original behavior of failing on write-locked table in
historical query.
35b679b9 assumed that SELECT_LEX::lock_type influences anything, but
actually at this point table is already locked. Original bug report
was tempesta-tech/mariadb#102
A temporary table is needed for window function computation but if only a NAMED WINDOW SPEC
is used and there is no window function, then there is no need to create a temporary
table as there is no stage to compute WINDOW FUNCTION
1. Code simplification:
Item_default_value handled all these values:
a. DEFAULT(field)
b. DEFAULT
c. IGNORE
and had various conditions to distinguish (a) from (b) and from (c).
Introducing a new abstract class Item_contextually_typed_value_specification,
to handle (b) and (c), so the hierarchy now looks as follows:
Item
Item_result_field
Item_ident
Item_field
Item_default_value - DEFAULT(field)
Item_contextually_typed_value_specification
Item_default_specification - DEFAULT
Item_ignore_specification - IGNORE
2. Introducing a new virtual method is_evaluable_expression() to
determine if an Item is:
- a normal expression, so its val_xxx()/get_date() methods can be called
- or a just an expression substitute, whose value methods cannot be called.
3. Disallowing Items that are not evalualble expressions in table value
constructors.
For a unique key if all the keyparts are NOT NULL or the predicates involving
the keyparts is NULL rejecting, then we can use EQ_REF access instead of ref
access with the unique key
The reason for this is to make all temporary file names similar and
also to be able to figure out from where a #sql-xxx name orginates.
New format is for most cases:
'#sql-name-current_pid-thread_id[-increment]'
Where name is one of subselect, alter, exchange, temptable or backup
The exceptions are:
ALTER PARTITION shadow files:
'#sql-shadow-thread_id-'original_table_name'
Names used with temp pool:
'#sql-name-current_pid-pool_number'
- Print the rowid filters that are available for use with each table.
- Make print_best_access_for_table() print which filter it has picked.
- Make best_access_path() print the filter for considered ref accesses.
* rename to a generic name
* move remaning initializations from query exec to prepare time
* simplify/unify key handling in open_table_from_share and delayed
* remove dead code
* move tests where they belong
- multi_range_read_info_const now uses the new records_in_range interface
- Added handler::avg_io_cost()
- Don't calculate avg_io_cost() in get_sweep_read_cost if avg_io_cost is
not 1.0. In this case we trust the avg_io_cost() from the handler.
- Changed test_quick_select to use TIME_FOR_COMPARE instead of
TIME_FOR_COMPARE_IDX to align this with the rest of the code.
- Fixed bug when using test_if_cheaper_ordering where we didn't use
keyread if index was changed
- Fixed a bug where we didn't use index only read when using order-by-index
- Added keyread_time() to HEAP.
The default keyread_time() was optimized for blocks and not suitable for
HEAP. The effect was the HEAP prefered table scans over ranges for btree
indexes.
- Fixed get_sweep_read_cost() for HEAP tables
- Ensure that range and ref have same cost for simple ranges
Added a small cost (MULTI_RANGE_READ_SETUP_COST) to ranges to ensure
we favior ref for range for simple queries.
- Fixed that matching_candidates_in_table() uses same number of records
as the rest of the optimizer
- Added avg_io_cost() to JT_EQ_REF cost. This helps calculate the cost for
HEAP and temporary tables better. A few tests changed because of this.
- heap::read_time() and heap::keyread_time() adjusted to not add +1.
This was to ensure that handler::keyread_time() doesn't give
higher cost for heap tables than for normal tables. One effect of
this is that heap and derived tables stored in heap will prefer
key access as this is now regarded as cheap.
- Changed cost for index read in sql_select.cc to match
multi_range_read_info_const(). All index cost calculation is now
done trough one function.
- 'ref' will now use quick_cost for keys if it exists. This is done
so that for '=' ranges, 'ref' is prefered over 'range'.
- scan_time() now takes avg_io_costs() into account
- get_delayed_table_estimates() uses block_size and avg_io_cost()
- Removed default argument to test_if_order_by_key(); simplifies code
This was done to both simplify the code and also to be easier to handle
storage engines that are clustered on some other index than the primary
key.
As pk_is_clustering_key() and is_clustering_key now are using only
index_flags, these where removed from all storage engines.
MDEV-21606 Improve update handler (long unique keys on blobs)
MDEV-21470 MyISAM and Aria start_bulk_insert doesn't work with long unique
MDEV-21606 Bug fix for previous version of this code
MDEV-21819 2 Assertion `inited == NONE || update_handler != this'
- Move update_handler from TABLE to handler
- Move out initialization of update handler from ha_write_row() to
prepare_for_insert()
- Fixed that INSERT DELAYED works with update handler
- Give an error if using long unique with an autoincrement column
- Added handler function to check if table has long unique hash indexes
- Disable write cache in MyISAM and Aria when using update_handler as
if cache is used, the row will not be inserted until end of statement
and update_handler would not find conflicting rows.
- Removed not used handler argument from
check_duplicate_long_entries_update()
- Syntax cleanups
- Indentation fixes
- Don't use single character indentifiers for arguments
e.g.
- dont -> don't
- occurence -> occurrence
- succesfully -> successfully
- easyly -> easily
Also remove trailing space in selected files.
These changes span:
- server core
- Connect and Innobase storage engine code
- OQgraph, Sphinx and TokuDB storage engines
Related to MDEV-21769.
Create_tmp_table::add_fields(): Initialize uneven_delta= 0
to suppress the warning from GCC 9.2.1 and 10.0.1,
and consistently indent the code with spaces.
It was:
implicit conversion from 'ha_rows' (aka 'unsigned long long') to 'double'
changes value from 18446744073709551615 to 18446744073709551616
Follow what JOIN::get_examined_rows() does for similar code.
This task deals with packing the sort key inside the sort buffer, which would
lead to efficient usage of the memory allocated for the sort buffer.
The changes brought by this feature are
1) Sort buffers would have sort keys of variable length
2) The format for sort keys inside the sort buffer would look like
|<sort_length><null_byte><key_part1><null_byte><key_part2>.......|
sort_length is the extra bytes that are required to store the variable
length of a sort key.
3) When packing of sort key is done we store the ORIGINAL VALUES inside
the sort buffer and not the STRXFRM form (mem-comparable sort keys).
4) Special comparison function packed_keys_comparison() is introduced
to compare 2 sort keys.
This patch also contains contributions from Sergei Petrunia.
- Added unlikely() to optimize for not having optimizer trace enabled
- Made THD::trace_started() inline
- Added 'if (trace_enabled())' around some potentially expensive code
(not many found)
- Added ASSERT's to ensure we don't call expensive optimizer trace calls
if optimizer trace is not enabled
- Added length to Json_writer functions to speed up buffer writes
when optimizer trace is enabled.
- Changed LEX_CSTRING argument handling to not send full struct to writer
function on_add_str() functions now trusts length arguments
[Variant 2 of the fix: collect the attached conditions]
Problem:
make_join_select() has a section of code which starts with
"We plan to scan all rows. Check again if we should use an index."
the code in that section will [unnecessarily] re-run the range
optimizer using this condition:
condition_attached_to_current_table AND current_table's_ON_expr
Note that the original invocation of range optimizer in
make_join_statistics was done using the whole select's WHERE condition.
Taking the whole select's WHERE condition and using multiple-equalities
allowed the range optimizer to infer more range restrictions.
The fix:
- Do range optimization using a condition that is an AND of this table's
condition and all of the previous tables' conditions.
- Also, fix the range optimizer to prefer SEL_ARGs with type=KEY_RANGE
over SEL_ARGS with type=MAYBE_KEY, regardless of the key part.
Computing
key_and(
SEL_ARG(type=MAYBE_KEY key_part=1),
SEL_ARG(type=KEY_RANGE, key_part=2)
)
will now produce the SEL_ARG with type=KEY_RANGE.
