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MDEV-10139 Support for SEQUENCE objects
Working features: CREATE OR REPLACE [TEMPORARY] SEQUENCE [IF NOT EXISTS] name [ INCREMENT [ BY | = ] increment ] [ MINVALUE [=] minvalue | NO MINVALUE ] [ MAXVALUE [=] maxvalue | NO MAXVALUE ] [ START [ WITH | = ] start ] [ CACHE [=] cache ] [ [ NO ] CYCLE ] ENGINE=xxx COMMENT=".." SELECT NEXT VALUE FOR sequence_name; SELECT NEXTVAL(sequence_name); SELECT PREVIOUS VALUE FOR sequence_name; SELECT LASTVAL(sequence_name); SHOW CREATE SEQUENCE sequence_name; SHOW CREATE TABLE sequence_name; CREATE TABLE sequence-structure ... SEQUENCE=1 ALTER TABLE sequence RENAME TO sequence2; RENAME TABLE sequence TO sequence2; DROP [TEMPORARY] SEQUENCE [IF EXISTS] sequence_names Missing features - SETVAL(value,sequence_name), to be used with replication. - Check replication, including checking that sequence tables are marked not transactional. - Check that a commit happens for NEXT VALUE that changes table data (may already work) - ALTER SEQUENCE. ANSI SQL version of setval. - Share identical sequence entries to not add things twice to table list. - testing insert/delete/update/truncate/load data - Run and fix Alibaba sequence tests (part of mysql-test/suite/sql_sequence) - Write documentation for NEXT VALUE / PREVIOUS_VALUE - NEXTVAL in DEFAULT - Ensure that NEXTVAL in DEFAULT uses database from base table - Two NEXTVAL for same row should give same answer. - Oracle syntax sequence_table.nextval, without any FOR or FROM. - Sequence tables are treated as 'not read constant tables' by SELECT; Would be better if we would have a separate list for sequence tables so that select doesn't know about them, except if refereed to with FROM. Other things done: - Improved output for safemalloc backtrack - frm_type_enum changed to Table_type - Removed lex->is_view and replaced with lex->table_type. This allows use to more easy check if item is view, sequence or table. - Added table flag HA_CAN_TABLES_WITHOUT_ROLLBACK, needed for handlers that want's to support sequences - Added handler calls: - engine_name(), to simplify getting engine name for partition and sequences - update_first_row(), to be able to do efficient sequence implementations. - Made binlog_log_row() global to be able to call it from ha_sequence.cc - Added handler variable: row_already_logged, to be able to flag that the changed row is already logging to replication log. - Added CF_DB_CHANGE and CF_SCHEMA_CHANGE flags to simplify deny_updates_if_read_only_option() - Added sp_add_cfetch() to avoid new conflicts in sql_yacc.yy - Moved code for add_table_options() out from sql_show.cc::show_create_table() - Added String::append_longlong() and used it in sql_show.cc to simplify code. - Added extra option to dd_frm_type() and ha_table_exists to indicate if the table is a sequence. Needed by DROP SQUENCE to not drop a table.
This commit is contained in:
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sql/ha_sequence.h
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138
sql/ha_sequence.h
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#ifndef HA_SEQUENCE_INCLUDED
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#define HA_SEQUENCE_INCLUDED
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/*
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Copyright (c) 2017 Aliyun and/or its affiliates.
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Copyright (c) 2017 MariaDB corporation
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "sql_sequence.h"
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#include "table.h"
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#include "handler.h"
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extern handlerton *sql_sequence_hton;
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/*
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Sequence engine handler.
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The sequence engine is a logic engine. It doesn't store any data.
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All the sequence data stored into the base table which must support
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non rollback writes (HA_CAN_TABLES_WITHOUT_ROLLBACK)
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The sequence data (SEQUENCE class) is stored in TABLE_SHARE->sequence
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TABLE RULES:
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1. When table is created, one row is automaticlly inserted into
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the table. The table will always have one and only one row.
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2. Any inserts or updates to the table will be validated.
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3. Inserts will overwrite the original row.
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4. DELETE and TRUNCATE will not affect the table.
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Instead a warning will be given.
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5. Cache will be reset for any updates.
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CACHE RULES:
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SEQUENCE class is used to cache values that sequence defined.
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1. If hit cache, we can query back the sequence nextval directly
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instead of reading the underlying table.
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2. When run out of values, the sequence engine will reserve new values
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in update the base table.
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3. The cache is invalidated if any update on based table.
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*/
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class ha_sequence :public handler
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{
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private:
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handler *file;
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SEQUENCE *sequence; /* From table_share->sequence */
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public:
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ha_sequence(handlerton *hton, TABLE_SHARE *share);
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~ha_sequence();
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/* virtual function that are re-implemented for sequence */
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int open(const char *name, int mode, uint test_if_locked);
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int create(const char *name, TABLE *form,
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HA_CREATE_INFO *create_info);
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handler *clone(const char *name, MEM_ROOT *mem_root);
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int write_row(uchar *buf);
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int update_row(const uchar *old_data, uchar *new_data);
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Table_flags table_flags() const;
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/* One can't delete from sequence engine */
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int delete_row(const uchar *buf)
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{ return HA_ERR_WRONG_COMMAND; }
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/* One can't delete from sequence engine */
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int truncate()
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{ return HA_ERR_WRONG_COMMAND; }
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/* Can't use query cache */
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uint8 table_cache_type()
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{ return HA_CACHE_TBL_NOCACHE; }
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void print_error(int error, myf errflag);
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int info(uint);
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LEX_STRING *engine_name() { return hton_name(file->ht); }
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int external_lock(THD *thd, int lock_type);
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/* Functions that are directly mapped to the underlying handler */
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int rnd_init(bool scan)
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{ return file->rnd_init(scan); }
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int rnd_next(uchar *buf)
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{ return file->rnd_next(buf); }
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int rnd_end()
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{ return file->rnd_end(); }
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int rnd_pos(uchar *buf, uchar *pos)
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{ return file->rnd_pos(buf, pos); }
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void position(const uchar *record)
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{ return file->position(record); }
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const char *table_type() const
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{ return file->table_type(); }
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ulong index_flags(uint inx, uint part, bool all_parts) const
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{ return file->index_flags(inx, part, all_parts); }
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THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
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enum thr_lock_type lock_type)
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{ return file->store_lock(thd, to, lock_type); }
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int close(void)
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{ return file->close(); }
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const char **bas_ext() const
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{ return file->bas_ext(); }
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int delete_table(const char*name)
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{ return file->delete_table(name); }
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int rename_table(const char *from, const char *to)
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{ return file->rename_table(from, to); }
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void unbind_psi()
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{ return file->unbind_psi(); }
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void rebind_psi()
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{ return file->rebind_psi(); }
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bool auto_repair(int error) const
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{ return file->auto_repair(error); }
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int repair(THD* thd, HA_CHECK_OPT* check_opt)
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{ return file->repair(thd, check_opt); }
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bool check_and_repair(THD *thd)
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{ return file->check_and_repair(thd); }
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bool is_crashed() const
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{ return file->is_crashed(); }
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/* New methods */
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void register_original_handler(handler *file_arg)
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{
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file= file_arg;
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init(); /* Update cached_table_flags */
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}
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/* To inform handler that sequence is already locked by called */
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bool sequence_locked;
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};
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#endif
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