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mariadb/sql/create_tmp_table.h
Arcadiy Ivanov 11f859d9d3 Fix CI regressions from MDEV-38975 forward-port to main
Seven code fixes, a new test, and test re-recordings for issues found
by CI on PR #5222.

**NULL dereference in `create_tmp_field()`**: `SYS_REFCURSOR` plugin
returns NULL from `make_new_field()` (cursor values cannot be
materialized). The feature added `result->flags |= FIELD_PART_OF_TMP_UNIQUE`
without a NULL check. Added `if (result)` guard.

**xmltype identity loss and recursive CTE reclength mismatch in
`Item_type_holder::create_tmp_field_ex()`**: the blob_key dispatch now
requires both: (1) `type_handler_for_tmp_table()` returns
`blob_key_type_handler()`, AND (2) `dynamic_cast<Type_handler_blob_common*>`
confirms the original type is a native blob. Condition 1 excludes xmltype
(its override returns itself). Condition 2 excludes VARCHAR types promoted
via `varstring_type_handler()` -> `too_big_for_varchar()` ->
`blob_type_handler()`. Without condition 2, wide VARCHAR in recursive CTEs
(e.g. `cast('...' as varchar(1000))`) was promoted to `Field_blob_key` in
the main UNION DISTINCT table (`part_of_unique_key=true`) but stayed as
`Field_varchar` in the incremental table (`part_of_unique_key=false`),
causing a `reclength` mismatch assertion in
`select_union_recursive::send_data()` (`main.json_equals` crash).

**Spurious `reclength > HA_MAX_REC_LENGTH` in `pick_engine()`**: the
original `choose_engine()` (both 10.11 and upstream/main) never had a
reclength check. MDEV-38975 introduced it when replacing the
`blob_fields` condition. HEAP has no internal reclength limit --
`hp_create.c` stores `uint reclength` and allocates blocks of that size;
`max_supported_record_length()` is only checked in `unireg.cc` during
user-facing CREATE TABLE. I_S tables like SLAVE_STATUS routinely have
reclength ~880KB (13 bare `Varchar()` columns). The check forced them to
Aria where `fill_slave_status()` returned 0 rows. Removed the check and
the unused `reclength` parameter from `pick_engine()`.

**Multi-update `tmp_memory_table_size` override**: the 10.11 feature
overrode `big_tables=FALSE` for multi-update dedup tables. The forward-port
translated this as `tmp_memory_table_size=SIZE_T_MAX` when the variable
was 0. But `big_tables=FALSE` was a soft "don't force disk" hint, while
`tmp_memory_table_size=SIZE_T_MAX` overrides the user's explicit
`tmp_memory_table_size=0` directive. Since main removed `big_tables`
entirely (MDEV-19713), the override is not needed. Removed.

**Zero-length key rejection in `check_tmp_key()`**: reject `key_len == 0`
to prevent useless zero-length keys from being created by `add_tmp_key()`.
Reachable when all key parts are CHAR(0) NOT NULL: `key_length()` returns
0, the field is not nullable (no HA_KEY_NULL_LENGTH) and not
VARCHAR/BLOB/GEOMETRY (no HA_KEY_BLOB_LENGTH), so `fld_store_len` is 0
for every part. Without this guard, `check_tmp_key()` would accept the
key (0 <= max_key_length), and the optimizer would create a ref key that
cannot distinguish any rows. Added `heap.char0_key` test exercising this
via a materialized derived table with CHAR(0) NOT NULL join columns.

**Non-deterministic `column_compression` test**: HEAP blob support allows
compressed VARCHAR/TEXT temp tables to stay in HEAP instead of falling to
Aria, changing row iteration order. Added `--sorted_result` to the two
MDEV-24726 subqueries that lack `ORDER BY`.

Test changes:
- `spatial_utility_function_collect`: added ORDER BY to window function
  that lacked it (results were engine-row-order-dependent)
- `tmp_space_usage`: removed multi-update override; forced disk for
  MDEV-34016/34060 Aria-specific test sections (blob I_S tables now
  stay in MEMORY)
- `blob_update_overflow`: replaced `SHOW STATUS LIKE 'Created_tmp_%'`
  with targeted I_S query (Created_tmp_files varies on sanitizer builds)
- 'funcs_1.is_tables_is' ; re-recorded test as
  INFORMATION_SCHEMA.SLAVE_STATUS is now back as MEMORY table
- `column_compression`: added `--sorted_result` for MDEV-24726 queries
- `char0_key` (new): CHAR(0) NOT NULL derived table ref key rejection
- Re-recorded 8 tests for expected "temp table stays in MEMORY" changes
2026-10-11 18:42:13 +03:00

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2.8 KiB
C++

#ifndef CREATE_TMP_TABLE_INCLUDED
#define CREATE_TMP_TABLE_INCLUDED
/* Copyright (c) 2021, MariaDB Corporation.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
/*
Class for creating internal tempory tables in sql_select.cc
*/
class Create_tmp_table: public Data_type_statistics
{
protected:
// The following members are initialized only in start()
Field **m_from_field, **m_default_field;
KEY_PART_INFO *m_key_part_info;
uchar *m_group_buff, *m_bitmaps;
// The following members are initialized in ctor
uint m_alloced_field_count;
bool m_using_unique_constraint;
bool m_heap_expected;
uint m_temp_pool_slot;
ORDER *m_group;
bool m_distinct;
bool m_save_sum_fields;
bool m_with_cycle;
ulonglong m_select_options;
ha_rows m_rows_limit;
uint m_group_null_items;
// counter for distinct/other fields
uint m_field_count[2];
// counter for distinct/other fields which can be NULL
uint m_null_count[2];
// counter for distinct/other blob fields
uint m_blobs_count[2];
// counter for "tails" of bit fields which do not fit in a byte
uint m_uneven_bit[2];
public:
enum counter {distinct, other};
/*
shows which field we are processing: distinct/other (set in processing
cycles)
*/
counter current_counter;
Create_tmp_table(ORDER *group, bool distinct, bool save_sum_fields,
ulonglong select_options, ha_rows rows_limit);
virtual ~Create_tmp_table() {}
handlerton *pick_engine(THD *thd);
virtual bool choose_engine(THD *thd, TABLE *table, TMP_TABLE_PARAM *param);
void add_field(TABLE *table, Field *field, uint fieldnr,
bool force_not_null_cols);
TABLE *start(THD *thd,
TMP_TABLE_PARAM *param,
const LEX_CSTRING *table_alias);
bool add_fields(THD *thd, TABLE *table,
TMP_TABLE_PARAM *param, List<Item> &fields);
bool add_schema_fields(THD *thd, TABLE *table,
TMP_TABLE_PARAM *param,
const ST_SCHEMA_TABLE &schema_table);
bool finalize(THD *thd, TABLE *table, TMP_TABLE_PARAM *param,
bool do_not_open, bool keep_row_order);
void cleanup_on_failure(THD *thd, TABLE *table);
};
#endif /* CREATE_TMP_TABLE_INCLUDED */