Commit 5c1f8d18 authored by Kristofer Pettersson's avatar Kristofer Pettersson
Browse files

Bug#38002 table_cache consumes too much memory with blobs 

     
Tables in the table definition cache are keeping a cache buffer for blob
fields which can consume a lot of memory.
    
This patch introduces a maximum size threshold for these buffers.
parent 58daa8d5

sql/field.h

+1 −1
Original line number Diff line number Diff line
@@ -13,7 +13,6 @@ 
   along with this program; if not, write to the Free Software

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





/*

  Because of the function new_field() all field classes that have static

  variables must declare the size_of() member function.
@@ -1669,6 +1668,7 @@ class Field_blob :public Field_longstr { 
  }

  int reset(void) { bzero(ptr, packlength+sizeof(uchar*)); return 0; }

  void reset_fields() { bzero((uchar*) &value,sizeof(value)); }

  uint32 get_field_buffer_size(void) { return value.alloced_length(); }

#ifndef WORDS_BIGENDIAN

  static

#endif

sql/mysql_priv.h

+1 −0
Original line number Diff line number Diff line
@@ -2130,6 +2130,7 @@ int writefrm(const char* name, const uchar* data, size_t len); 
int closefrm(TABLE *table, bool free_share);

int read_string(File file, uchar* *to, size_t length);

void free_blobs(TABLE *table);

void free_field_buffers_larger_than(TABLE *table, uint32 size);

int set_zone(int nr,int min_zone,int max_zone);

ulong convert_period_to_month(ulong period);

ulong convert_month_to_period(ulong month);

sql/sql_base.cc

+2 −0
Original line number Diff line number Diff line
@@ -1369,6 +1369,8 @@ bool close_thread_table(THD *thd, TABLE **table_ptr) 
    DBUG_ASSERT(!table->is_children_attached());



    /* Free memory and reset for next loop */

    free_field_buffers_larger_than(table,MAX_TDC_BLOB_SIZE);

    

    table->file->ha_reset();

    table->in_use=0;

    if (unused_tables)

sql/table.cc

+22 −0
Original line number Diff line number Diff line
@@ -1999,6 +1999,28 @@ void free_blobs(register TABLE *table) 
}





/**

  Reclaim temporary blob storage which is bigger than 

  a threshold.

 

  @param table A handle to the TABLE object containing blob fields

  @param size The threshold value.

 

*/



void free_field_buffers_larger_than(TABLE *table, uint32 size)

{

  uint *ptr, *end;

  for (ptr= table->s->blob_field, end=ptr + table->s->blob_fields ;

       ptr != end ;

       ptr++)

  {

    Field_blob *blob= (Field_blob*) table->field[*ptr];

    if (blob->get_field_buffer_size() > size)

        blob->free();

  }

}



	/* Find where a form starts */

	/* if formname is NullS then only formnames is read */

sql/table.h

+3 −0
Original line number Diff line number Diff line
@@ -935,6 +935,9 @@ typedef struct st_schema_table 
#define VIEW_CHECK_ERROR      1

#define VIEW_CHECK_SKIP       2



/** The threshold size a blob field buffer before it is freed */

#define MAX_TDC_BLOB_SIZE 65536



struct st_lex;

class select_union;

class TMP_TABLE_PARAM;