diff options
Diffstat (limited to 'include/heap.h')
| -rw-r--r-- | include/heap.h | 51 |
1 files changed, 43 insertions, 8 deletions
diff --git a/include/heap.h b/include/heap.h index 63f2abbabc7..5e83a6e2cb5 100644 --- a/include/heap.h +++ b/include/heap.h @@ -63,18 +63,48 @@ typedef struct st_heap_ptrs struct st_level_info { - uint free_ptrs_in_block,records_under_level; - HP_PTRS *last_blocks; /* pointers to HP_PTRS or records */ + /* Number of unused slots in *last_blocks HP_PTRS block (0 for 0th level) */ + uint free_ptrs_in_block; + + /* + Maximum number of records that can be 'contained' inside of each element + of last_blocks array. For level 0 - 1, for level 1 - HP_PTRS_IN_NOD, for + level 2 - HP_PTRS_IN_NOD^2 and so forth. + */ + uint records_under_level; + + /* + Ptr to last allocated HP_PTRS (or records buffer for level 0) on this + level. + */ + HP_PTRS *last_blocks; }; -typedef struct st_heap_block /* The data is saved in blocks */ + +/* + Heap table records and hash index entries are stored in HP_BLOCKs. + HP_BLOCK is used as a 'growable array' of fixed-size records. Size of record + is recbuffer bytes. + The internal representation is as follows: + HP_BLOCK is a hierarchical structure of 'blocks'. + A block at level 0 is an array records_in_block records. + A block at higher level is an HP_PTRS structure with pointers to blocks at + lower levels. + At the highest level there is one top block. It is stored in HP_BLOCK::root. + + See hp_find_block for a description of how record pointer is obtained from + its index. + See hp_get_new_block +*/ + +typedef struct st_heap_block { - HP_PTRS *root; + HP_PTRS *root; /* Top-level block */ struct st_level_info level_info[HP_MAX_LEVELS+1]; - uint levels; - uint records_in_block; /* Records in a heap-block */ + uint levels; /* number of used levels */ + uint records_in_block; /* Records in one heap-block */ uint recbuffer; /* Length of one saved record */ - ulong last_allocated; /* Blocks allocated, used by keys */ + ulong last_allocated; /* number of records there is allocated space for */ } HP_BLOCK; struct st_heap_info; /* For referense */ @@ -87,6 +117,11 @@ typedef struct st_hp_keydef /* Key definition with open */ uint8 algorithm; /* HASH / BTREE */ HA_KEYSEG *seg; HP_BLOCK block; /* Where keys are saved */ + /* + Number of buckets used in hash table. Used only to provide + #records estimates for heap key scans. + */ + ha_rows hash_buckets; TREE rb_tree; int (*write_key)(struct st_heap_info *info, struct st_hp_keydef *keyinfo, const byte *record, byte *recpos); @@ -102,7 +137,7 @@ typedef struct st_heap_share ulong min_records,max_records; /* Params to open */ ulong data_length,index_length; uint records; /* records */ - uint blength; + uint blength; /* records rounded up to 2^n */ uint deleted; /* Deleted records in database */ uint reclength; /* Length of one record */ uint changed; |