- Added missing information about database of corresponding table for various types of commands
- Update some typos
- Reviewed by: <vicentiu@mariadb.org>
UNION ALL queries are a subject of optimization introduced in MDEV-334
when creation of a temporary table is skipped.
While there is a check for this optimization in Explain_union::print_explain()
there was no such in Explain_union::print_explain_json(). This resulted in
printing irrelevant data like:
"union_result": {
"table_name": "<union2,3>",
"access_type": "ALL",
"r_loops": 0,
"r_rows": null
in case when creation of the temporary table was actually optimized out.
This commits adds a check whether the temporary table was actually created
during the UNION ALL processing and eliminates printing of the irrelevant data.
This bug caused crashes of the server when processing queries with table
value constructors (TVC) that contained subqueries and were used itself as
subselects. For such TVCs the following transformation is applied at the
prepare stage:
VALUES (v1), ... (vn) => SELECT * FROM (VALUES (v1), ... (vn)) tvc_x.
This transformation allows to reduce the problem of evaluation of TVCs used
as subselects to the problem of evaluation of regular subselects.
The transformation is implemented in the wrap_tvc(). The code the function
to mimic the behaviour of the parser when processing the result of the
transformation. However this imitation was not free of some flaws. First
the function called the method exclude() that completely destroyed the
select tree structures below the transformed TVC. Second the function
used the procedure mysql_new_select to create st_select_lex nodes for
both wrapping select of the transformation and TVC. This also led to
constructing of invalid select tree structures.
The patch actually re-engineers the code of wrap_tvc().
Approved by Oleksandr Byelkin <sanja@mariadb.com>
- Adding optional qualifiers to data types:
CREATE TABLE t1 (a schema.DATE);
Qualifiers now work only for three pre-defined schemas:
mariadb_schema
oracle_schema
maxdb_schema
These schemas are virtual (hard-coded) for now, but may turn into real
databases on disk in the future.
- mariadb_schema.TYPE now always resolves to a true MariaDB data
type TYPE without sql_mode specific translations.
- oracle_schema.DATE translates to MariaDB DATETIME.
- maxdb_schema.TIMESTAMP translates to MariaDB DATETIME.
- Fixing SHOW CREATE TABLE to use a qualifier for a data type TYPE
if the current sql_mode translates TYPE to something else.
The above changes fix the reported problem, so this script:
SET sql_mode=ORACLE;
CREATE TABLE t2 AS SELECT mariadb_date_column FROM t1;
is now replicated as:
SET sql_mode=ORACLE;
CREATE TABLE t2 (mariadb_date_column mariadb_schema.DATE);
and the slave can unambiguously treat DATE as the true MariaDB DATE
without ORACLE specific translation to DATETIME.
Similar,
SET sql_mode=MAXDB;
CREATE TABLE t2 AS SELECT mariadb_timestamp_column FROM t1;
is now replicated as:
SET sql_mode=MAXDB;
CREATE TABLE t2 (mariadb_timestamp_column mariadb_schema.TIMESTAMP);
so the slave treats TIMESTAMP as the true MariaDB TIMESTAMP
without MAXDB specific translation to DATETIME.
Problem:
========
During point in time recovery of binary log syntax error is reported for
BEGIN statement and recovery fails.
Analysis:
=========
In MariaDB 10.3 and later, setting the sql_mode system variable to Oracle
allows the server to understand a subset of Oracle's PL/SQL language. When
sql_mode=ORACLE is set, it switches the parser from the MariaDB parser to
Oracle compatible parser. With this change 'BEGIN' is not considered as
'START TRANSACTION'. Hence the syntax error is reported.
Fix:
===
At preset 'BEGIN' query is generated from 'Gtid_log_event::print'. The current
session specific 'sql_mode' information is not present as part of
'Gtid_log_event'. If it was available then, mysqlbinlog tool can make use of
'sql_mode == ORACLE' and can output "START TRANSACTION" in this particular
mode and for other sql_modes it will write "BEGIN" as part of output. Since it
is not available 'mysqlbinlog' tool will output all 'BEGIN' statements as
'START TRANSACTION' irrespective of 'sql_mode'.
When backpatching a forward GOTO label, the old code erroneously
used CURSOR/HANDLER difference between context frames "c" and "a" to tune
a cpop/hpop command. So the cpop/hpop command later tried to pop
all cursors/handlers declared between "a" and "c", but those between
"b" and "c" were not cpushed/hpoped yet during the execution of "GOTO x".
Fixing the code to use the difference between frames "b" and "a" only.
BEGIN -- a
...
GOTO x; -- b
...
<<x>> -- c
...
END -- d
(Backported to 10.3, addressed review input)
Sj_materialization_picker::check_qep(): fix error in cost/fanout
calculations:
- for each join prefix, add #prefix_rows / TIME_FOR_COMPARE to the cost,
like best_extension_by_limited_search does
- Remove the fanout produced by the subquery tables.
- Also take into account join condition selectivity
optimize_wo_join_buffering() (used by LooseScan and FirstMatch)
- also add #prefix_rows / TIME_FOR_COMPARE to the cost of each prefix.
- Also take into account join condition selectivity
In collaboration with Sergey Vojtovich <svoj@mariadb.org>
The COMPRESSED clause is now a part of the data type and goes immediately
after the data type and length, but before the CHARACTER SET clause,
and before column attributes such as DEFAULT, COLLATE, ON UPDATE,
SYSTEM VERSIONING, engine specific column attributes.
In the old reduction, the COMPRESSED clause was a column attribute.
New syntax:
<varchar or text data type> <length> <compression> <character set> <column attributes>
<varbinary or blob data type> <length> <compression> <column attributes>
New syntax examples:
VARCHAR(1000) COMPRESSED CHARACTER SET latin1 DEFAULT ''
BLOB COMPRESSED DEFAULT ''
Deprecate syntax examples:
VARCHAR(1000) CHARACTER SET latin1 COMPRESSED DEFAULT ''
TEXT CHARACTER SET latin1 DEFAULT '' COMPRESSED
VARBINARY(1000) DEFAULT '' COMPRESSED
As a side effect:
- COMPRESSED is not valid as an SP label name in SQL/PSM routines any more
(but it's still valid as an SP label name in sql_mode=ORACLE)
- COMPRESSED is now allowed in combination with GENERATED ALWAYS AS:
TEXT COMPRESSED GENERATED ALWAYS AS REPEAT('a',1000)
query with VALUES()
A table value constructor can be used in all contexts where a select
can be used. In particular an ORDER BY clause or a LIMIT clause or both
of them can be attached to a table value constructor to produce a new
query. Unfortunately execution of such queries was not supported.
This patch fixes the problem.
This patch was originally made by Anel Husakovic.
Skip `PACKAGE` and `PACKAGE BODY` records quickly.
These stored objects do not have any parameters or return values
(only procedures and functions have).
So no needs to build a `CREATE` statement
(in `Sp_handler::sp_load_for_information_schema()`) and parse it:
this won't give us any data useful for `INFORMATION_SCHEMA.PARAMETERS`.
sp_instr_cursor_copy_struct::exec_core() created TYPELIBs on a wrong mem_root,
the one which is initialized in sp_head::execute(), this code:
/* init per-instruction memroot */
init_sql_alloc(&execute_mem_root, "per_instruction_memroot",
MEM_ROOT_BLOCK_SIZE, 0, MYF(0));
This memory root cleans up after every sp_instr_xxx executed, so later
sp_instr_cfetch::execute() tried to use already freed and trashed memory.
Changing sp_instr_cursor_copy_struct::exec_core() to call tmp.export_structure()
inside this block (not outside of it):
thd->set_n_backup_active_arena(thd->spcont->callers_arena, ¤t_arena);
...
thd->restore_active_arena(thd->spcont->callers_arena, ¤t_arena);
So now TYPELIBs created by sp_instr_cursor_copy_struct::exec_core() are
still available and valid when sp_instr_cfetch::execute() is called.
They are freed at the end of dispatch_command() corresponding to
the "CALL p1" statement.
MDEV-17660 sql_mode=ORACLE: Some keywords do not work as label names: history, system, versioning, without
MDEV-17661 Add sql_mode specific tokens for the keyword DECODE
Changing the way how a cursor is opened to fetch its structure only,
e.g. for a cursor FOR loop record variable.
The old methods with setting thd->lex->limit_rows_examined to an Item_uint(0)
was not reliable and could push these messages into diagnostics area:
The query examined at least 1 rows, which exceeds LIMIT ROWS EXAMINED (0)
The new method should be more reliable, as it completely prevents the call
of do_select() in JOIN::exec_inner() during the cursor structure discovery,
so the execution of the cursor SELECT query returns immediately after the
preparation step (when the result row structure becomes known),
without even entering the code that fetches the result rows.
1. Adding LEX::make_item_sysvar() and reusing it
in sql_yacc.yy and sql_yacc_ora.yy.
Removing the "opt_component" rule.
2. Renaming rules to better reflect their purpose:
- keyword to keyword_ident
- keyword_sp to keyword_label
- keyword_sp_not_data_type to keyword_sp_var_and_label
Also renaming:
- sp_decl_ident_keyword to keyword_sp_decl for naming consistency
- keyword_alias to keyword_table_alias,
for consistency with ident_table_alias
- keyword_sp_data_type to keyword_data_type,
as it has nothing SP-specific.
3. Moving GLOBAL_SYM, LOCAL_SYM, SESSION_SYM from
keyword_sp_var_and_label to a separate rule keyword_sysvar_type.
We don't have system variables with these names anyway.
Adding ident_sysvar_name and using it in the grammar that needs
a system variable name instead of ident_or_text.
This removed a number of shift/reduce conflicts
between GLOBAL_SYM/LOCAL_SYM/SESSION_SYM as a variable scope and
as a variable name.
4. Moving keywords BEGIN_SYM, END (in both *.yy fiels)
and EXCEPTION_SYM (in sql_yacc_ora.yy) into a separate
rule keyword_sp_block_section, because in Oracle verb keywords
(COMMIT, DO, HANDLER, OPEN, REPAIR, ROLLBACK, SAVEPOINT, SHUTDOWN, TRUNCATE)
are good variables names and can appear in e.g. DECLARE,
while block keywords (BEGIN, END, EXCEPTION) are not good variable names
and cannot appear in DECLARE.
5. Further splitting keyword_directly_not_assignable in sql_yacc_ora.yy:
moving keyword_sp_verb_clause out. Renaming the rest of
keyword_directly_not_assignable to keyword_sp_head,
which represents keywords that can appear in optional
clauses in CREATE PROCEDURE/FUNCTION/TRIGGER.
6. Renaming keyword_sp_verb_clause to keyword_verb_clause,
as now it does not contains anything SP-specific.
As a result or #4,#5,#6, the rule keyword_directly_not_assignable
was replaced to three separate rules:
- keyword_sp_block
- keyword_sp_head
- keyword_verb_clause
Adding the same rules in sql_yacc.yy, for unification.
6. Adding keyword_sp_head and keyword_verb_clause into keyword_sp_decl.
This fixes MDEV-16244.
7. Reorganizing the rest of keyword related rules into two groups:
a. Rules defining a list of keywords and consisting of only terminal symbols:
- keyword_sp_var_not_label
- keyword_sp_head
- keyword_sp_verb_clause
- keyword_sp_block_section
- keyword_sysvar_type
b. Rules that combine the above lists into keyword places:
- keyword_table_alias
- keyword_ident
- keyword_label
- keyword_sysvar_name
- keyword_sp_decl
Rules from the group "b" use on the right side only rules
from the group "a" (with optional terminal symbols added).
Rules from the group "b" DO NOT mutually use each other any more.
This makes them easier to read (and see the difference between them).
Sorting the right sides of the group "b" keyword rules alphabetically,
for yet better readability.
Merging the following features from sql_yacc.yy to sql_yacc_ora.yy:
- system versioning
- column compression
- table value constructor
- spatial predicate WITHIN
- DELETE_DOMAIN_ID
The code passing positions in the query to constructors of
Rewritable_query_parameter descendants (e.g. Item_splocal)
was not reliable. It used various Lex_input_stream methods:
- get_tok_start()
- get_tok_start_prev()
- get_tok_end()
- get_ptr()
to find positions of the recently scanned tokens.
The challenge was mostly to choose between get_tok_start()
and get_tok_start_prev(), taking into account to the current
grammar (depending if lookahead takes place before
or after we read the positions in every particular rule).
But this approach did not work at all in combination
with token contractions, when MYSQLlex() translates
two tokens into one token ID, for example:
WITH ROLLUP -> WITH_ROLLUP_SYM
As a result, the tokenizer is already one more token ahead.
So in query fragment:
"GROUP BY d, spvar WITH ROLLUP"
get_tok_start() points to "ROLLUP".
get_tok_start_prev() points to "WITH".
As a result, it was "WITH" who was erroneously replaced
to NAME_CONST() instead of "spvar".
This patch modifies the code to do it a different way.
Changes:
1. For keywords and identifiers, the tokenizer now
returns LEX_CTRING pointing directly to the query
fragment. So query positions are now just available using:
- $1.str - for the beginning of a token
- $1.str+$1.length - for the end of a token
2. Identifiers are not allocated on the THD memory root
in the tokenizer any more. Allocation is now done
on later stages, in methods like LEX::create_item_ident().
3. Two LEX_CSTRING based structures were added:
- Lex_ident_cli_st - used to store the "client side"
identifier representation, pointing to the
query fragment. Note, these identifiers
are encoded in @@character_set_client
and can have broken byte sequences.
- Lex_ident_sys_st - used to store the "server side"
identifier representation, pointing to the
THD allocated memory. This representation
guarantees that the identifier was checked
for being well-formed, and is encoded in utf8.
4. To distinguish between two identifier types
in the grammar, two Bison types were added:
<ident_cli> and <ident_sys>
5. All non-reserved keywords were marked as
being of the type <ident_cli>.
All reserved keywords are still of the type NONE.
6. All curly brackets in rules collecting
non-reserved keywords into non-terminal
symbols were removed, e.g.:
Was:
keyword_sp_data_type:
BIT_SYM {}
| BOOLEAN_SYM {}
Now:
keyword_sp_data_type:
BIT_SYM
| BOOLEAN_SYM
This is important NOT to have brackets here!!!!
This is needed to make sure that the underlying
Lex_ident_cli_ststructure correctly passes up to
the calling rule.
6. The code to scan identifiers and keywords
was moved from lex_one_token() into new
Lex_input_stream methods:
scan_ident_sysvar()
scan_ident_start()
scan_ident_middle()
scan_ident_delimited()
This was done to:
- get rid of enormous amount of references to &yylval->lex_str
- and remove a lot of references like lip->xxx
7. The allocating functionality which puts identifiers on the
THD memory root now resides in methods of Lex_ident_sys_st,
and in THD::to_ident_sys_alloc().
get_quoted_token() was removed.
8. Cleanup: check_simple_select() was moved as a method to LEX.
9. Cleanup: Some more functionality was moved from *.yy
to new methods were added to LEX:
make_item_colon_ident_ident()
make_item_func_call_generic()
create_item_qualified_asterisk()
