Index Statistics

Following is the definition of the mco_index_stat_t structure which provides memory usage statistics for an index:

 
    typedef struct mco_index_stat_t_ 
    {
        uint2         class_code;             /* class code to which the index belongs */
        uint4         type;                   /* type, MCO_IDXST_ flags */
        char        * plabel;                 /* the index label */
        mco_counter_t keys_num;               /* number of keys in the index */
        mco_counter_t pages_num;              /* number of pages used by the index */
        mco_counter_t avg_cmp;                /* average number of comparisons needed to locate an element */
        mco_counter_t max_cmp;                /* maximum number of comparisons needed to locate an element */
        union {
            mco_index_stat_tree_t   btree;     /* specific btree stats */
            mco_index_stat_kdtree_t kdtree;    /* specific kdtree stats */
            mco_index_stat_hash_t   hash;      /* specific hash stats */
            mco_index_stat_tree_t   ptree;     /* specific patricia trie stats */
            mco_index_stat_rtree_t  rtree;     /* specific r-tree stats */
            mco_index_stat_meta_t   meta;      /* specific meta-index stats */
        } spec;
    } mco_index_stat_t, * mco_index_stat_h;
     

 

class_code	The class code to which the index belongs
type	A bitmap of MCO_IDXST_ flags as defined below
plabel	The index label
keys_num	The number of keys in the index
pages_num	The number of pages used by the index
avg_cmp	The average number of comparisons needed to locate an element
max_cmp	The maximum number of comparisons needed to locate an element
spec	A union containing specific statistics depending on the type of index (see table below).

 

The element type is defined by a combination of the following bit values:

Type
MCO_IDXST_TYPE_MEM	In-memory index
MCO_IDXST_TYPE_DISK	Persistent index
Nature
MCO_IDXST_NATURE_BTREE	Binary tree
MCO_IDXST_NATURE_PTREE	Patricia trie
MCO_IDXST_NATURE_KDTREE	KD-tree
MCO_IDXST_NATURE_HASH	Hash index
MCO_IDXST_NATURE_META	Meta-index
MCO_IDXST_NATURE_RTREE	R-tree
Feature
MCO_IDXST_FEATURE_UNIQUE	Unique
MCO_IDXST_FEATURE_UDF	User-defined
MCO_IDXST_FEATURE_THICK	Thick index
MCO_IDXST_FEATURE_OPTIMIZED	Uses optimized compare & hash functions
Function
MCO_IDXST_FUNCTION_REGULAR	Regular class index
MCO_IDXST_FUNCTION_OID	Object-ID meta-index
MCO_IDXST_FUNCTION_AUTOOID	Auto object-ID meta-index
MCO_IDXST_FUNCTION_AUTOID	Auto id meta-index
MCO_IDXST_FUNCTION_LIST	List meta-index

 

The union element spec is one of the following depending on the type of index: