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hash

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    Provides information about the vBucket hash tables.

    Syntax

    Request syntax:

    cbstats [hostname]:11210 hash
    cbstats [hostname]:11210 hash detail

    Description

    Requesting these stats does affect performance, so don’t do it too regularly, but it’s useful for debugging certain types of performance issues. For example, if your hash table is tuned to have too few buckets for the data load within it, the max_depth will be too large, and performance will suffer.

    It is also possible to get more detailed hash tables stats by using ‘hash detail’. This prints per-vbucket stats. Each stat is prefixed with vb_ followed by a number, a colon, then the individual stat name. For example, the stat representing the size of the hash table for vbucket 0 is vb_0:size=.

    Options

    None

    Examples

    Hash request

    cbstats 10.5.2.54:11210 hash

    Hash response

     avg_count:    0
     avg_max:      0
     avg_min:      0
     largest_max:  0
     largest_min:  0
     max_count:    0
     min_count:    0
     total_counts: 0
    Table 1. Hash response stats
    Stat Description

    avg_count

    The average number of items per vbucket.

    avg_max

    The average max depth of a vbucket hash table.

    avg_min

    The average min depth of a vbucket hash table.

    largest_max

    The largest hash table depth of in all vbuckets.

    largest_min

    The largest minimum hash table depth of all vbuckets.

    max_count

    The largest number of items in a vbucket.

    min_count

    The smallest number of items in a vbucket.

    total_counts

    The total number of items in all vbuckets.

    Hash detail

    cbstats 10.5.2.54:11210 hash detail

    Hash detail response

     avg_count:                0
     avg_max:                  0
     avg_min:                  0
     largest_max:              0
     largest_min:              0
     max_count:                0
     min_count:                0
     total_counts:             0
     vb_0:counted:             0
     vb_0:locks:               5
     vb_0:max_depth:           0
     vb_0:mem_size:            0
     vb_0:mem_size_counted:    0
     vb_0:min_depth:           0
     vb_0:reported:            0
     vb_0:resized:             0
     vb_0:size:                3079
     vb_0:state:               replica
     ...
    Table 2. Hash detail response stats
    Stat Description

    state

    The current state of this vbucket.

    size

    Number of hash buckets.

    locks

    Number of locks covering hash table operations.

    min_depth

    Minimum number of items found in a bucket.

    max_depth

    Maximum number of items found in a bucket.

    reported

    Number of items this hash table reports having.

    counted

    Number of items found while walking the table.

    resized

    Number of times the hash table resized.

    mem_size

    Running sum of memory used by each item.

    mem_size_counted

    Counted sum of current memory used by each item.