1. 06 Oct, 2017 3 commits
    • Eugene Kosov's avatar
      fix a data race in debug build (#456) · e59d080f
      Eugene Kosov authored
      fix a data race in debug build
      
      This particular one flooded TSAN report.
      e59d080f
    • Marko Mäkelä's avatar
      MDEV-11369 Instant ADD COLUMN for InnoDB · a4948daf
      Marko Mäkelä authored
      For InnoDB tables, adding, dropping and reordering columns has
      required a rebuild of the table and all its indexes. Since MySQL 5.6
      (and MariaDB 10.0) this has been supported online (LOCK=NONE), allowing
      concurrent modification of the tables.
      
      This work revises the InnoDB ROW_FORMAT=REDUNDANT, ROW_FORMAT=COMPACT
      and ROW_FORMAT=DYNAMIC so that columns can be appended instantaneously,
      with only minor changes performed to the table structure. The counter
      innodb_instant_alter_column in INFORMATION_SCHEMA.GLOBAL_STATUS
      is incremented whenever a table rebuild operation is converted into
      an instant ADD COLUMN operation.
      
      ROW_FORMAT=COMPRESSED tables will not support instant ADD COLUMN.
      
      Some usability limitations will be addressed in subsequent work:
      
      MDEV-13134 Introduce ALTER TABLE attributes ALGORITHM=NOCOPY
      and ALGORITHM=INSTANT
      MDEV-14016 Allow instant ADD COLUMN, ADD INDEX, LOCK=NONE
      
      The format of the clustered index (PRIMARY KEY) is changed as follows:
      
      (1) The FIL_PAGE_TYPE of the root page will be FIL_PAGE_TYPE_INSTANT,
      and a new field PAGE_INSTANT will contain the original number of fields
      in the clustered index ('core' fields).
      If instant ADD COLUMN has not been used or the table becomes empty,
      or the very first instant ADD COLUMN operation is rolled back,
      the fields PAGE_INSTANT and FIL_PAGE_TYPE will be reset
      to 0 and FIL_PAGE_INDEX.
      
      (2) A special 'default row' record is inserted into the leftmost leaf,
      between the page infimum and the first user record. This record is
      distinguished by the REC_INFO_MIN_REC_FLAG, and it is otherwise in the
      same format as records that contain values for the instantly added
      columns. This 'default row' always has the same number of fields as
      the clustered index according to the table definition. The values of
      'core' fields are to be ignored. For other fields, the 'default row'
      will contain the default values as they were during the ALTER TABLE
      statement. (If the column default values are changed later, those
      values will only be stored in the .frm file. The 'default row' will
      contain the original evaluated values, which must be the same for
      every row.) The 'default row' must be completely hidden from
      higher-level access routines. Assertions have been added to ensure
      that no 'default row' is ever present in the adaptive hash index
      or in locked records. The 'default row' is never delete-marked.
      
      (3) In clustered index leaf page records, the number of fields must
      reside between the number of 'core' fields (dict_index_t::n_core_fields
      introduced in this work) and dict_index_t::n_fields. If the number
      of fields is less than dict_index_t::n_fields, the missing fields
      are replaced with the column value of the 'default row'.
      Note: The number of fields in the record may shrink if some of the
      last instantly added columns are updated to the value that is
      in the 'default row'. The function btr_cur_trim() implements this
      'compression' on update and rollback; dtuple::trim() implements it
      on insert.
      
      (4) In ROW_FORMAT=COMPACT and ROW_FORMAT=DYNAMIC records, the new
      status value REC_STATUS_COLUMNS_ADDED will indicate the presence of
      a new record header that will encode n_fields-n_core_fields-1 in
      1 or 2 bytes. (In ROW_FORMAT=REDUNDANT records, the record header
      always explicitly encodes the number of fields.)
      
      We introduce the undo log record type TRX_UNDO_INSERT_DEFAULT for
      covering the insert of the 'default row' record when instant ADD COLUMN
      is used for the first time. Subsequent instant ADD COLUMN can use
      TRX_UNDO_UPD_EXIST_REC.
      
      This is joint work with Vin Chen (陈福荣) from Tencent. The design
      that was discussed in April 2017 would not have allowed import or
      export of data files, because instead of the 'default row' it would
      have introduced a data dictionary table. The test
      rpl.rpl_alter_instant is exactly as contributed in pull request #408.
      The test innodb.instant_alter is based on a contributed test.
      
      The redo log record format changes for ROW_FORMAT=DYNAMIC and
      ROW_FORMAT=COMPACT are as contributed. (With this change present,
      crash recovery from MariaDB 10.3.1 will fail in spectacular ways!)
      Also the semantics of higher-level redo log records that modify the
      PAGE_INSTANT field is changed. The redo log format version identifier
      was already changed to LOG_HEADER_FORMAT_CURRENT=103 in MariaDB 10.3.1.
      
      Everything else has been rewritten by me. Thanks to Elena Stepanova,
      the code has been tested extensively.
      
      When rolling back an instant ADD COLUMN operation, we must empty the
      PAGE_FREE list after deleting or shortening the 'default row' record,
      by calling either btr_page_empty() or btr_page_reorganize(). We must
      know the size of each entry in the PAGE_FREE list. If rollback left a
      freed copy of the 'default row' in the PAGE_FREE list, we would be
      unable to determine its size (if it is in ROW_FORMAT=COMPACT or
      ROW_FORMAT=DYNAMIC) because it would contain more fields than the
      rolled-back definition of the clustered index.
      
      UNIV_SQL_DEFAULT: A new special constant that designates an instantly
      added column that is not present in the clustered index record.
      
      len_is_stored(): Check if a length is an actual length. There are
      two magic length values: UNIV_SQL_DEFAULT, UNIV_SQL_NULL.
      
      dict_col_t::def_val: The 'default row' value of the column.  If the
      column is not added instantly, def_val.len will be UNIV_SQL_DEFAULT.
      
      dict_col_t: Add the accessors is_virtual(), is_nullable(), is_instant(),
      instant_value().
      
      dict_col_t::remove_instant(): Remove the 'instant ADD' status of
      a column.
      
      dict_col_t::name(const dict_table_t& table): Replaces
      dict_table_get_col_name().
      
      dict_index_t::n_core_fields: The original number of fields.
      For secondary indexes and if instant ADD COLUMN has not been used,
      this will be equal to dict_index_t::n_fields.
      
      dict_index_t::n_core_null_bytes: Number of bytes needed to
      represent the null flags; usually equal to UT_BITS_IN_BYTES(n_nullable).
      
      dict_index_t::NO_CORE_NULL_BYTES: Magic value signalling that
      n_core_null_bytes was not initialized yet from the clustered index
      root page.
      
      dict_index_t: Add the accessors is_instant(), is_clust(),
      get_n_nullable(), instant_field_value().
      
      dict_index_t::instant_add_field(): Adjust clustered index metadata
      for instant ADD COLUMN.
      
      dict_index_t::remove_instant(): Remove the 'instant ADD' status
      of a clustered index when the table becomes empty, or the very first
      instant ADD COLUMN operation is rolled back.
      
      dict_table_t: Add the accessors is_instant(), is_temporary(),
      supports_instant().
      
      dict_table_t::instant_add_column(): Adjust metadata for
      instant ADD COLUMN.
      
      dict_table_t::rollback_instant(): Adjust metadata on the rollback
      of instant ADD COLUMN.
      
      prepare_inplace_alter_table_dict(): First create the ctx->new_table,
      and only then decide if the table really needs to be rebuilt.
      We must split the creation of table or index metadata from the
      creation of the dictionary table records and the creation of
      the data. In this way, we can transform a table-rebuilding operation
      into an instant ADD COLUMN operation. Dictionary objects will only
      be added to cache when table rebuilding or index creation is needed.
      The ctx->instant_table will never be added to cache.
      
      dict_table_t::add_to_cache(): Modified and renamed from
      dict_table_add_to_cache(). Do not modify the table metadata.
      Let the callers invoke dict_table_add_system_columns() and if needed,
      set can_be_evicted.
      
      dict_create_sys_tables_tuple(), dict_create_table_step(): Omit the
      system columns (which will now exist in the dict_table_t object
      already at this point).
      
      dict_create_table_step(): Expect the callers to invoke
      dict_table_add_system_columns().
      
      pars_create_table(): Before creating the table creation execution
      graph, invoke dict_table_add_system_columns().
      
      row_create_table_for_mysql(): Expect all callers to invoke
      dict_table_add_system_columns().
      
      create_index_dict(): Replaces row_merge_create_index_graph().
      
      innodb_update_n_cols(): Renamed from innobase_update_n_virtual().
      Call my_error() if an error occurs.
      
      btr_cur_instant_init(), btr_cur_instant_init_low(),
      btr_cur_instant_root_init():
      Load additional metadata from the clustered index and set
      dict_index_t::n_core_null_bytes. This is invoked
      when table metadata is first loaded into the data dictionary.
      
      dict_boot(): Initialize n_core_null_bytes for the four hard-coded
      dictionary tables.
      
      dict_create_index_step(): Initialize n_core_null_bytes. This is
      executed as part of CREATE TABLE.
      
      dict_index_build_internal_clust(): Initialize n_core_null_bytes to
      NO_CORE_NULL_BYTES if table->supports_instant().
      
      row_create_index_for_mysql(): Initialize n_core_null_bytes for
      CREATE TEMPORARY TABLE.
      
      commit_cache_norebuild(): Call the code to rename or enlarge columns
      in the cache only if instant ADD COLUMN is not being used.
      (Instant ADD COLUMN would copy all column metadata from
      instant_table to old_table, including the names and lengths.)
      
      PAGE_INSTANT: A new 13-bit field for storing dict_index_t::n_core_fields.
      This is repurposing the 16-bit field PAGE_DIRECTION, of which only the
      least significant 3 bits were used. The original byte containing
      PAGE_DIRECTION will be accessible via the new constant PAGE_DIRECTION_B.
      
      page_get_instant(), page_set_instant(): Accessors for the PAGE_INSTANT.
      
      page_ptr_get_direction(), page_get_direction(),
      page_ptr_set_direction(): Accessors for PAGE_DIRECTION.
      
      page_direction_reset(): Reset PAGE_DIRECTION, PAGE_N_DIRECTION.
      
      page_direction_increment(): Increment PAGE_N_DIRECTION
      and set PAGE_DIRECTION.
      
      rec_get_offsets(): Use the 'leaf' parameter for non-debug purposes,
      and assume that heap_no is always set.
      Initialize all dict_index_t::n_fields for ROW_FORMAT=REDUNDANT records,
      even if the record contains fewer fields.
      
      rec_offs_make_valid(): Add the parameter 'leaf'.
      
      rec_copy_prefix_to_dtuple(): Assert that the tuple is only built
      on the core fields. Instant ADD COLUMN only applies to the
      clustered index, and we should never build a search key that has
      more than the PRIMARY KEY and possibly DB_TRX_ID,DB_ROLL_PTR.
      All these columns are always present.
      
      dict_index_build_data_tuple(): Remove assertions that would be
      duplicated in rec_copy_prefix_to_dtuple().
      
      rec_init_offsets(): Support ROW_FORMAT=REDUNDANT records whose
      number of fields is between n_core_fields and n_fields.
      
      cmp_rec_rec_with_match(): Implement the comparison between two
      MIN_REC_FLAG records.
      
      trx_t::in_rollback: Make the field available in non-debug builds.
      
      trx_start_for_ddl_low(): Remove dangerous error-tolerance.
      A dictionary transaction must be flagged as such before it has generated
      any undo log records. This is because trx_undo_assign_undo() will mark
      the transaction as a dictionary transaction in the undo log header
      right before the very first undo log record is being written.
      
      btr_index_rec_validate(): Account for instant ADD COLUMN
      
      row_undo_ins_remove_clust_rec(): On the rollback of an insert into
      SYS_COLUMNS, revert instant ADD COLUMN in the cache by removing the
      last column from the table and the clustered index.
      
      row_search_on_row_ref(), row_undo_mod_parse_undo_rec(), row_undo_mod(),
      trx_undo_update_rec_get_update(): Handle the 'default row'
      as a special case.
      
      dtuple_t::trim(index): Omit a redundant suffix of an index tuple right
      before insert or update. After instant ADD COLUMN, if the last fields
      of a clustered index tuple match the 'default row', there is no
      need to store them. While trimming the entry, we must hold a page latch,
      so that the table cannot be emptied and the 'default row' be deleted.
      
      btr_cur_optimistic_update(), btr_cur_pessimistic_update(),
      row_upd_clust_rec_by_insert(), row_ins_clust_index_entry_low():
      Invoke dtuple_t::trim() if needed.
      
      row_ins_clust_index_entry(): Restore dtuple_t::n_fields after calling
      row_ins_clust_index_entry_low().
      
      rec_get_converted_size(), rec_get_converted_size_comp(): Allow the number
      of fields to be between n_core_fields and n_fields. Do not support
      infimum,supremum. They are never supposed to be stored in dtuple_t,
      because page creation nowadays uses a lower-level method for initializing
      them.
      
      rec_convert_dtuple_to_rec_comp(): Assign the status bits based on the
      number of fields.
      
      btr_cur_trim(): In an update, trim the index entry as needed. For the
      'default row', handle rollback specially. For user records, omit
      fields that match the 'default row'.
      
      btr_cur_optimistic_delete_func(), btr_cur_pessimistic_delete():
      Skip locking and adaptive hash index for the 'default row'.
      
      row_log_table_apply_convert_mrec(): Replace 'default row' values if needed.
      In the temporary file that is applied by row_log_table_apply(),
      we must identify whether the records contain the extra header for
      instantly added columns. For now, we will allocate an additional byte
      for this for ROW_T_INSERT and ROW_T_UPDATE records when the source table
      has been subject to instant ADD COLUMN. The ROW_T_DELETE records are
      fine, as they will be converted and will only contain 'core' columns
      (PRIMARY KEY and some system columns) that are converted from dtuple_t.
      
      rec_get_converted_size_temp(), rec_init_offsets_temp(),
      rec_convert_dtuple_to_temp(): Add the parameter 'status'.
      
      REC_INFO_DEFAULT_ROW = REC_INFO_MIN_REC_FLAG | REC_STATUS_COLUMNS_ADDED:
      An info_bits constant for distinguishing the 'default row' record.
      
      rec_comp_status_t: An enum of the status bit values.
      
      rec_leaf_format: An enum that replaces the bool parameter of
      rec_init_offsets_comp_ordinary().
      a4948daf
    • Eugene Kosov's avatar
      fix TSAN build with Clang · 3a418242
      Eugene Kosov authored
      3a418242
  2. 05 Oct, 2017 2 commits
  3. 04 Oct, 2017 10 commits
  4. 03 Oct, 2017 16 commits
  5. 02 Oct, 2017 9 commits