~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2006 MySQL AB

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*

  Single table and multi table updates of tables.

  Multi-table updates were introduced by Sinisa & Monty

*/

#include "mysql_priv.h"

#include "sql_select.h"

/* Return 0 if row hasn't changed */

bool compare_record(TABLE *table)

{

  if (table->s->blob_fields + table->s->varchar_fields == 0)

    return cmp_record(table,record[1]);

  /* Compare null bits */

  if (memcmp(table->null_flags,

	     table->null_flags+table->s->rec_buff_length,

	     table->s->null_bytes))

    return true;				// Diff in NULL value

  /* Compare updated fields */

  for (Field **ptr= table->field ; *ptr ; ptr++)

  {

    if (bitmap_is_set(table->write_set, (*ptr)->field_index) &&

	(*ptr)->cmp_binary_offset(table->s->rec_buff_length))

      return true;

  }

  return false;

}

/*

  check that all fields are real fields

  SYNOPSIS

    check_fields()

    thd             thread handler

    items           Items for check

  RETURN

    true  Items can't be used in UPDATE

    false Items are OK

*/

static bool check_fields(THD *thd, List<Item> &items)

{

  List_iterator<Item> it(items);

  Item *item;

  Item_field *field;

  while ((item= it++))

  {

    if (!(field= item->filed_for_view_update()))

    {

      /* item has name, because it comes from VIEW SELECT list */

      my_error(ER_NONUPDATEABLE_COLUMN, MYF(0), item->name);

      return true;

    }

    /*

      we make temporary copy of Item_field, to avoid influence of changing

      result_field on Item_ref which refer on this field

    */

    thd->change_item_tree(it.ref(), new Item_field(thd, field));

  }

  return false;

}

/**

  Re-read record if more columns are needed for error message.

  If we got a duplicate key error, we want to write an error

  message containing the value of the duplicate key. If we do not have

  all fields of the key value in record[0], we need to re-read the

  record with a proper read_set.

  @param[in] error   error number

  @param[in] table   table

*/

static void prepare_record_for_error_message(int error, TABLE *table)

{

  Field **field_p;

  Field *field;

  uint keynr;

  MY_BITMAP unique_map; /* Fields in offended unique. */

  my_bitmap_map unique_map_buf[bitmap_buffer_size(MAX_FIELDS)];

  /*

    Only duplicate key errors print the key value.

    If storage engine does always read all columns, we have the value alraedy.

  */

  if ((error != HA_ERR_FOUND_DUPP_KEY) ||

      !(table->file->ha_table_flags() & HA_PARTIAL_COLUMN_READ))

    return;

  /*

    Get the number of the offended index.

    We will see MAX_KEY if the engine cannot determine the affected index.

  */

  if ((keynr= table->file->get_dup_key(error)) >= MAX_KEY)

    return;

  /* Create unique_map with all fields used by that index. */

  bitmap_init(&unique_map, unique_map_buf, table->s->fields, false);

  table->mark_columns_used_by_index_no_reset(keynr, &unique_map);

  /* Subtract read_set and write_set. */

  bitmap_subtract(&unique_map, table->read_set);

  bitmap_subtract(&unique_map, table->write_set);

  /*

    If the unique index uses columns that are neither in read_set

    nor in write_set, we must re-read the record.

    Otherwise no need to do anything.

  */

  if (bitmap_is_clear_all(&unique_map))

    return;

  /* Get identifier of last read record into table->file->ref. */

  table->file->position(table->record[0]);

  /* Add all fields used by unique index to read_set. */

  bitmap_union(table->read_set, &unique_map);

  /* Tell the engine about the new set. */

  table->file->column_bitmaps_signal();

  /* Read record that is identified by table->file->ref. */

  (void) table->file->rnd_pos(table->record[1], table->file->ref);

  /* Copy the newly read columns into the new record. */

  for (field_p= table->field; (field= *field_p); field_p++)

    if (bitmap_is_set(&unique_map, field->field_index))

      field->copy_from_tmp(table->s->rec_buff_length);

  return;

}

/*

  Process usual UPDATE

  SYNOPSIS

    mysql_update()

    thd			thread handler

    fields		fields for update

    values		values of fields for update

    conds		WHERE clause expression

    order_num		number of elemen in ORDER BY clause

    order		ORDER BY clause list

    limit		limit clause

    handle_duplicates	how to handle duplicates

  RETURN

    0  - OK

    2  - privilege check and openning table passed, but we need to convert to

         multi-update because of view substitution

    1  - error

*/

int mysql_update(THD *thd,

                 TABLE_LIST *table_list,

                 List<Item> &fields,

                 List<Item> &values,

                 COND *conds,

                 uint order_num, ORDER *order,

                 ha_rows limit,

                 enum enum_duplicates handle_duplicates __attribute__((unused)),

                 bool ignore)

{

  bool		using_limit= limit != HA_POS_ERROR;

  bool		safe_update= test(thd->options & OPTION_SAFE_UPDATES);

  bool		used_key_is_modified, transactional_table, will_batch;

  bool		can_compare_record;

  int		error, loc_error;

  uint		used_index= MAX_KEY, dup_key_found;

  bool          need_sort= true;

  uint          table_count= 0;

  ha_rows	updated, found;

  key_map	old_covering_keys;

  TABLE		*table;

  SQL_SELECT	*select;

  READ_RECORD	info;

  SELECT_LEX    *select_lex= &thd->lex->select_lex;

  bool          need_reopen;

  uint64_t     id;

  List<Item> all_fields;

  THD::killed_state killed_status= THD::NOT_KILLED;

  for ( ; ; )

  {

    if (open_tables(thd, &table_list, &table_count, 0))

      return(1);

    if (!lock_tables(thd, table_list, table_count, &need_reopen))

      break;

    if (!need_reopen)

      return(1);

    close_tables_for_reopen(thd, &table_list);

  }

  if (mysql_handle_derived(thd->lex, &mysql_derived_prepare) ||

      (thd->fill_derived_tables() &&

       mysql_handle_derived(thd->lex, &mysql_derived_filling)))

    return(1);

  MYSQL_UPDATE_START();

  thd_proc_info(thd, "init");

  table= table_list->table;

  /* Calculate "table->covering_keys" based on the WHERE */

  table->covering_keys= table->s->keys_in_use;

  table->quick_keys.clear_all();

  if (mysql_prepare_update(thd, table_list, &conds, order_num, order))

    goto abort;

  old_covering_keys= table->covering_keys;		// Keys used in WHERE

  /* Check the fields we are going to modify */

  if (setup_fields_with_no_wrap(thd, 0, fields, MARK_COLUMNS_WRITE, 0, 0))

    goto abort;                               /* purecov: inspected */

  if (table->timestamp_field)

  {

    // Don't set timestamp column if this is modified

    if (bitmap_is_set(table->write_set,

                      table->timestamp_field->field_index))

      table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;

    else

    {

      if (table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_UPDATE ||

          table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_BOTH)

        bitmap_set_bit(table->write_set,

                       table->timestamp_field->field_index);

    }

  }

  if (setup_fields(thd, 0, values, MARK_COLUMNS_READ, 0, 0))

  {

    free_underlaid_joins(thd, select_lex);

    goto abort;                               /* purecov: inspected */

  }

  if (select_lex->inner_refs_list.elements &&

    fix_inner_refs(thd, all_fields, select_lex, select_lex->ref_pointer_array))

  {

    MYSQL_UPDATE_END();

    return(-1);

  }

  if (conds)

  {

    Item::cond_result cond_value;

    conds= remove_eq_conds(thd, conds, &cond_value);

    if (cond_value == Item::COND_FALSE)

      limit= 0;                                   // Impossible WHERE

  }

  /*

    If a timestamp field settable on UPDATE is present then to avoid wrong

    update force the table handler to retrieve write-only fields to be able

    to compare records and detect data change.

  */

  if (table->file->ha_table_flags() & HA_PARTIAL_COLUMN_READ &&

      table->timestamp_field &&

      (table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_UPDATE ||

       table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_BOTH))

    bitmap_union(table->read_set, table->write_set);

  // Don't count on usage of 'only index' when calculating which key to use

  table->covering_keys.clear_all();

  /* Update the table->file->stats.records number */

  table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);

  select= make_select(table, 0, 0, conds, 0, &error);

  if (error || !limit ||

      (select && select->check_quick(thd, safe_update, limit)))

  {

    delete select;

    free_underlaid_joins(thd, select_lex);

    if (error)

      goto abort;				// Error in where

    MYSQL_UPDATE_END();

    my_ok(thd);				// No matching records

    return(0);

  }

  if (!select && limit != HA_POS_ERROR)

  {

    if ((used_index= get_index_for_order(table, order, limit)) != MAX_KEY)

      need_sort= false;

  }

  /* If running in safe sql mode, don't allow updates without keys */

  if (table->quick_keys.is_clear_all())

  {

    thd->server_status|=SERVER_QUERY_NO_INDEX_USED;

    if (safe_update && !using_limit)

    {

      my_message(ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE,

		 ER(ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE), MYF(0));

      goto err;

    }

  }

  table->mark_columns_needed_for_update();

  /* Check if we are modifying a key that we are used to search with */

  if (select && select->quick)

  {

    used_index= select->quick->index;

    used_key_is_modified= (!select->quick->unique_key_range() &&

                          select->quick->is_keys_used(table->write_set));

  }

  else

  {

    used_key_is_modified= 0;

    if (used_index == MAX_KEY)                  // no index for sort order

      used_index= table->file->key_used_on_scan;

    if (used_index != MAX_KEY)

      used_key_is_modified= is_key_used(table, used_index, table->write_set);

  }

  if (used_key_is_modified || order)

  {

    /*

      We can't update table directly;  We must first search after all

      matching rows before updating the table!

    */

    if (used_index < MAX_KEY && old_covering_keys.is_set(used_index))

    {

      table->key_read=1;

      table->mark_columns_used_by_index(used_index);

    }

    else

    {

      table->use_all_columns();

    }

    /* note: We avoid sorting avoid if we sort on the used index */

    if (order && (need_sort || used_key_is_modified))

    {

      /*

	Doing an ORDER BY;  Let filesort find and sort the rows we are going

	to update

        NOTE: filesort will call table->prepare_for_position()

      */

      uint         length= 0;

      SORT_FIELD  *sortorder;

      ha_rows examined_rows;

      table->sort.io_cache = (IO_CACHE *) my_malloc(sizeof(IO_CACHE),

						    MYF(MY_FAE | MY_ZEROFILL));

      if (!(sortorder=make_unireg_sortorder(order, &length, NULL)) ||

          (table->sort.found_records= filesort(thd, table, sortorder, length,

                                               select, limit, 1,

                                               &examined_rows))

          == HA_POS_ERROR)

      {

	goto err;

      }

      /*

	Filesort has already found and selected the rows we want to update,

	so we don't need the where clause

      */

      delete select;

      select= 0;

    }

    else

    {

      /*

	We are doing a search on a key that is updated. In this case

	we go trough the matching rows, save a pointer to them and

	update these in a separate loop based on the pointer.

      */

      IO_CACHE tempfile;

      if (open_cached_file(&tempfile, mysql_tmpdir,TEMP_PREFIX,

			   DISK_BUFFER_SIZE, MYF(MY_WME)))

	goto err;

      /* If quick select is used, initialize it before retrieving rows. */

      if (select && select->quick && select->quick->reset())

        goto err;

      table->file->try_semi_consistent_read(1);

      /*

        When we get here, we have one of the following options:

        A. used_index == MAX_KEY

           This means we should use full table scan, and start it with

           init_read_record call

        B. used_index != MAX_KEY

           B.1 quick select is used, start the scan with init_read_record

           B.2 quick select is not used, this is full index scan (with LIMIT)

               Full index scan must be started with init_read_record_idx

      */

      if (used_index == MAX_KEY || (select && select->quick))

        init_read_record(&info,thd,table,select,0,1);

      else

        init_read_record_idx(&info, thd, table, 1, used_index);

      thd_proc_info(thd, "Searching rows for update");

      ha_rows tmp_limit= limit;

      while (!(error=info.read_record(&info)) && !thd->killed)

      {

	if (!(select && select->skip_record()))

	{

          if (table->file->was_semi_consistent_read())

	    continue;  /* repeat the read of the same row if it still exists */

	  table->file->position(table->record[0]);

	  if (my_b_write(&tempfile,table->file->ref,

			 table->file->ref_length))

	  {

	    error=1; /* purecov: inspected */

	    break; /* purecov: inspected */

	  }

	  if (!--limit && using_limit)

	  {

	    error= -1;

	    break;

	  }

	}

	else

	  table->file->unlock_row();

      }

      if (thd->killed && !error)

	error= 1;				// Aborted

      limit= tmp_limit;

      table->file->try_semi_consistent_read(0);

      end_read_record(&info);

      /* Change select to use tempfile */

      if (select)

      {

	delete select->quick;

	if (select->free_cond)

	  delete select->cond;

	select->quick=0;

	select->cond=0;

      }

      else

      {

	select= new SQL_SELECT;

	select->head=table;

      }

      if (reinit_io_cache(&tempfile,READ_CACHE,0L,0,0))

	error=1; /* purecov: inspected */

      select->file=tempfile;			// Read row ptrs from this file

      if (error >= 0)

	goto err;

    }

    if (table->key_read)

      table->restore_column_maps_after_mark_index();

  }

  if (ignore)

    table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);

  if (select && select->quick && select->quick->reset())

    goto err;

  table->file->try_semi_consistent_read(1);

  init_read_record(&info,thd,table,select,0,1);

  updated= found= 0;

  /* Generate an error when trying to set a NOT NULL field to NULL. */

  thd->count_cuted_fields= ignore ? CHECK_FIELD_WARN

                                  : CHECK_FIELD_ERROR_FOR_NULL;

  thd->cuted_fields=0L;

  thd_proc_info(thd, "Updating");

  transactional_table= table->file->has_transactions();

  thd->abort_on_warning= test(!ignore &&

                              (thd->variables.sql_mode &

                               (MODE_STRICT_TRANS_TABLES |

                                MODE_STRICT_ALL_TABLES)));

  will_batch= !table->file->start_bulk_update();

  /*

    Assure that we can use position()

    if we need to create an error message.

  */

  if (table->file->ha_table_flags() & HA_PARTIAL_COLUMN_READ)

    table->prepare_for_position();

  /*

    We can use compare_record() to optimize away updates if

    the table handler is returning all columns OR if

    if all updated columns are read

  */

  can_compare_record= (!(table->file->ha_table_flags() &

                         HA_PARTIAL_COLUMN_READ) ||

                       bitmap_is_subset(table->write_set, table->read_set));

  while (!(error=info.read_record(&info)) && !thd->killed)

  {

    if (!(select && select->skip_record()))

    {

      if (table->file->was_semi_consistent_read())

        continue;  /* repeat the read of the same row if it still exists */

      store_record(table,record[1]);

      if (fill_record(thd, fields, values, 0))

        break; /* purecov: inspected */

      found++;

      if (!can_compare_record || compare_record(table))

      {

        if (will_batch)

        {

          /*

            Typically a batched handler can execute the batched jobs when:

            1) When specifically told to do so

            2) When it is not a good idea to batch anymore

            3) When it is necessary to send batch for other reasons

               (One such reason is when READ's must be performed)

            1) is covered by exec_bulk_update calls.

            2) and 3) is handled by the bulk_update_row method.

            bulk_update_row can execute the updates including the one

            defined in the bulk_update_row or not including the row

            in the call. This is up to the handler implementation and can

            vary from call to call.

            The dup_key_found reports the number of duplicate keys found

            in those updates actually executed. It only reports those if

            the extra call with HA_EXTRA_IGNORE_DUP_KEY have been issued.

            If this hasn't been issued it returns an error code and can

            ignore this number. Thus any handler that implements batching

            for UPDATE IGNORE must also handle this extra call properly.

            If a duplicate key is found on the record included in this

            call then it should be included in the count of dup_key_found

            and error should be set to 0 (only if these errors are ignored).

          */

          error= table->file->ha_bulk_update_row(table->record[1],

                                                 table->record[0],

                                                 &dup_key_found);

          limit+= dup_key_found;

          updated-= dup_key_found;

        }

        else

        {

          /* Non-batched update */

	  error= table->file->ha_update_row(table->record[1],

                                            table->record[0]);

        }

        if (!error || error == HA_ERR_RECORD_IS_THE_SAME)

	{

          if (error != HA_ERR_RECORD_IS_THE_SAME)

            updated++;

          else

            error= 0;

	}

 	else if (!ignore ||

                 table->file->is_fatal_error(error, HA_CHECK_DUP_KEY))

	{

          /*

            If (ignore && error is ignorable) we don't have to

            do anything; otherwise...

          */

          myf flags= 0;

          if (table->file->is_fatal_error(error, HA_CHECK_DUP_KEY))

            flags|= ME_FATALERROR; /* Other handler errors are fatal */

          prepare_record_for_error_message(error, table);

	  table->file->print_error(error,MYF(flags));

	  error= 1;

	  break;

	}

      }

      if (!--limit && using_limit)

      {

        /*

          We have reached end-of-file in most common situations where no

          batching has occurred and if batching was supposed to occur but

          no updates were made and finally when the batch execution was

          performed without error and without finding any duplicate keys.

          If the batched updates were performed with errors we need to

          check and if no error but duplicate key's found we need to

          continue since those are not counted for in limit.

        */

        if (will_batch &&

            ((error= table->file->exec_bulk_update(&dup_key_found)) ||

             dup_key_found))

        {

 	  if (error)

          {

            /* purecov: begin inspected */

            /*

              The handler should not report error of duplicate keys if they

              are ignored. This is a requirement on batching handlers.

            */

            prepare_record_for_error_message(error, table);

            table->file->print_error(error,MYF(0));

            error= 1;

            break;

            /* purecov: end */

          }

          /*

            Either an error was found and we are ignoring errors or there

            were duplicate keys found. In both cases we need to correct

            the counters and continue the loop.

          */

          limit= dup_key_found; //limit is 0 when we get here so need to +

          updated-= dup_key_found;

        }

        else

        {

	  error= -1;				// Simulate end of file

	  break;

        }

      }

    }

    else

      table->file->unlock_row();

    thd->row_count++;

  }

  dup_key_found= 0;

  /*

    Caching the killed status to pass as the arg to query event constuctor;

    The cached value can not change whereas the killed status can

    (externally) since this point and change of the latter won't affect

    binlogging.

    It's assumed that if an error was set in combination with an effective

    killed status then the error is due to killing.

  */

  killed_status= thd->killed; // get the status of the volatile

  // simulated killing after the loop must be ineffective for binlogging

  error= (killed_status == THD::NOT_KILLED)?  error : 1;

  if (error &&

      will_batch &&

      (loc_error= table->file->exec_bulk_update(&dup_key_found)))

    /*

      An error has occurred when a batched update was performed and returned

      an error indication. It cannot be an allowed duplicate key error since

      we require the batching handler to treat this as a normal behavior.

      Otherwise we simply remove the number of duplicate keys records found

      in the batched update.

    */

  {

    /* purecov: begin inspected */

    prepare_record_for_error_message(loc_error, table);

    table->file->print_error(loc_error,MYF(ME_FATALERROR));

    error= 1;

    /* purecov: end */

  }

  else

    updated-= dup_key_found;

  if (will_batch)

    table->file->end_bulk_update();

  table->file->try_semi_consistent_read(0);

  if (!transactional_table && updated > 0)

    thd->transaction.stmt.modified_non_trans_table= true;

  end_read_record(&info);

  delete select;

  thd_proc_info(thd, "end");

  VOID(table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY));

  /*

    error < 0 means really no error at all: we processed all rows until the

    last one without error. error > 0 means an error (e.g. unique key

    violation and no IGNORE or REPLACE). error == 0 is also an error (if

    preparing the record or invoking before triggers fails). See

    ha_autocommit_or_rollback(error>=0) and return(error>=0) below.

    Sometimes we want to binlog even if we updated no rows, in case user used

    it to be sure master and slave are in same state.

  */

  if ((error < 0) || thd->transaction.stmt.modified_non_trans_table)

  {

    if (mysql_bin_log.is_open())

    {

      if (error < 0)

        thd->clear_error();

      if (thd->binlog_query(THD::ROW_QUERY_TYPE,

                            thd->query, thd->query_length,

                            transactional_table, false, killed_status) &&

          transactional_table)

      {

        error=1;				// Rollback update

      }

    }

    if (thd->transaction.stmt.modified_non_trans_table)

      thd->transaction.all.modified_non_trans_table= true;

  }

  assert(transactional_table || !updated || thd->transaction.stmt.modified_non_trans_table);

  free_underlaid_joins(thd, select_lex);

  /* If LAST_INSERT_ID(X) was used, report X */

  id= thd->arg_of_last_insert_id_function ?

    thd->first_successful_insert_id_in_prev_stmt : 0;

  MYSQL_UPDATE_END();

  if (error < 0)

  {

    char buff[STRING_BUFFER_USUAL_SIZE];

    sprintf(buff, ER(ER_UPDATE_INFO), (ulong) found, (ulong) updated,

	    (ulong) thd->cuted_fields);

    thd->row_count_func=

      (thd->client_capabilities & CLIENT_FOUND_ROWS) ? found : updated;

    my_ok(thd, (ulong) thd->row_count_func, id, buff);

  }

  thd->count_cuted_fields= CHECK_FIELD_IGNORE;		/* calc cuted fields */

  thd->abort_on_warning= 0;

  return((error >= 0 || thd->is_error()) ? 1 : 0);

err:

  delete select;

  free_underlaid_joins(thd, select_lex);

  if (table->key_read)

  {

    table->key_read=0;

    table->file->extra(HA_EXTRA_NO_KEYREAD);

  }

  thd->abort_on_warning= 0;

abort:

  MYSQL_UPDATE_END();

  return(1);

}

/*

  Prepare items in UPDATE statement

  SYNOPSIS

    mysql_prepare_update()

    thd			- thread handler

    table_list		- global/local table list

    conds		- conditions

    order_num		- number of ORDER BY list entries

    order		- ORDER BY clause list

  RETURN VALUE

    false OK

    true  error

*/

bool mysql_prepare_update(THD *thd, TABLE_LIST *table_list,

			 Item **conds, uint order_num, ORDER *order)

{

  List<Item> all_fields;

  SELECT_LEX *select_lex= &thd->lex->select_lex;

  /*

    Statement-based replication of UPDATE ... LIMIT is not safe as order of

    rows is not defined, so in mixed mode we go to row-based.

    Note that we may consider a statement as safe if ORDER BY primary_key

    is present. However it may confuse users to see very similiar statements

    replicated differently.

  */

  if (thd->lex->current_select->select_limit)

  {

    thd->lex->set_stmt_unsafe();

    thd->set_current_stmt_binlog_row_based_if_mixed();

  }

  thd->lex->allow_sum_func= 0;

  if (setup_tables_and_check_access(thd, &select_lex->context, 

                                    &select_lex->top_join_list,

                                    table_list,

                                    &select_lex->leaf_tables,

                                    false) ||

      setup_conds(thd, table_list, select_lex->leaf_tables, conds) ||

      select_lex->setup_ref_array(thd, order_num) ||

      setup_order(thd, select_lex->ref_pointer_array,

		  table_list, all_fields, all_fields, order))