mariadb/storage/maria/ma_delete_all.c

/* Copyright (C) 2006 MySQL AB & MySQL Finland AB & TCX DataKonsult 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 */

/* Remove all rows from a MARIA table */
/* This clears the status information and truncates files */

#include "maria_def.h"
#include "trnman.h"

/**
   @brief deletes all rows from a table

   @param  info             Maria handler

   @return Operation status
     @retval 0      ok
     @retval 1      error
*/

int maria_delete_all_rows(MARIA_HA *info)
{
  MARIA_SHARE *share=info->s;
  my_bool log_record;
  DBUG_ENTER("maria_delete_all_rows");

  if (share->options & HA_OPTION_READ_ONLY_DATA)
  {
    DBUG_RETURN(my_errno=EACCES);
  }
  /**
     @todo LOCK take X-lock on table here.
     When we have versioning, if some other thread is looking at this table,
     we cannot shrink the file like this.
  */
  if (_ma_readinfo(info,F_WRLCK,1))
    DBUG_RETURN(my_errno);
  log_record= share->now_transactional && !share->temporary;
  if (_ma_mark_file_changed(info))
    goto err;

  if (log_record)
  {
    /*
      This record will be used by Recovery to finish the deletion if it
      crashed. We force it because it's a non-undoable operation.
    */
    LSN lsn;
    LEX_STRING log_array[TRANSLOG_INTERNAL_PARTS + 1];
    uchar log_data[FILEID_STORE_SIZE];
    log_array[TRANSLOG_INTERNAL_PARTS + 0].str=    (char*) log_data;
    log_array[TRANSLOG_INTERNAL_PARTS + 0].length= sizeof(log_data);
    if (unlikely(translog_write_record(&lsn, LOGREC_REDO_DELETE_ALL,
                                       info->trn, info, 0,
                                       sizeof(log_array)/sizeof(log_array[0]),
                                       log_array, log_data, NULL) ||
                 translog_flush(lsn)))
      goto err;
  }

  /*
    For recovery it matters that this is called after writing the log record,
    so that resetting state.records and state.checksum actually happens under
    log's mutex.
  */
  _ma_reset_status(info);

  /*
    If we are using delayed keys or if the user has done changes to the tables
    since it was locked then there may be key blocks in the page cache. Or
    there may be data blocks there. We need to throw them away or they may
    re-enter the emptied table later.
  */
  if (_ma_flush_table_files(info, MARIA_FLUSH_DATA|MARIA_FLUSH_INDEX,
                            FLUSH_IGNORE_CHANGED, FLUSH_IGNORE_CHANGED) ||
      my_chsize(info->dfile.file, 0, 0, MYF(MY_WME)) ||
      my_chsize(share->kfile.file, share->base.keystart, 0, MYF(MY_WME))  )
    goto err;

  if (_ma_initialize_data_file(share, info->dfile.file))
    goto err;

  /*
    The operations above on the index/data file will be forced to disk at
    Checkpoint or maria_close() time. So we can reset:
  */
  if (log_record)
    info->trn->rec_lsn= LSN_IMPOSSIBLE;

  VOID(_ma_writeinfo(info,WRITEINFO_UPDATE_KEYFILE));
#ifdef HAVE_MMAP
  /* Resize mmaped area */
  rw_wrlock(&info->s->mmap_lock);
  _ma_remap_file(info, (my_off_t)0);
  rw_unlock(&info->s->mmap_lock);
#endif
  allow_break();			/* Allow SIGHUP & SIGINT */
  DBUG_RETURN(0);

err:
  {
    int save_errno=my_errno;
    VOID(_ma_writeinfo(info,WRITEINFO_UPDATE_KEYFILE));
    info->update|=HA_STATE_WRITTEN;	/* Buffer changed */
    /**
       @todo RECOVERY if we come here, Recovery may later apply the REDO above,
       which may be wrong. Not fixing it now, as anyway this way of deleting
       rows will have to be re-examined when we have versioning.
    */
    allow_break();			/* Allow SIGHUP & SIGINT */
    DBUG_RETURN(my_errno=save_errno);
  }
} /* maria_delete_all_rows */


/*
  Reset status information

  SYNOPSIS
    _ma_reset_status()
    maria	Maria handler

  DESCRIPTION
    Resets data and index file information as if the file would be empty
    Files are not touched.
*/

void _ma_reset_status(MARIA_HA *info)
{
  MARIA_SHARE *share= info->s;
  MARIA_STATE_INFO *state= &share->state;
  uint i;

  info->state->records= info->state->del= state->split= 0;
  state->changed=  0;                            /* File is optimized */
  state->dellink= HA_OFFSET_ERROR;
  state->sortkey=  (ushort) ~0;
  info->state->key_file_length= share->base.keystart;
  info->state->data_file_length= 0;
  info->state->empty= info->state->key_empty= 0;
  info->state->checksum= 0;

  /* Drop the delete key chain. */
  state->key_del= HA_OFFSET_ERROR;
  /* Clear all keys */
  for (i=0 ; i < share->base.keys ; i++)
    state->key_root[i]= HA_OFFSET_ERROR;
}