redis commands common object

OBJECT encoding

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Get information about a key

Usage is OBJECT encoding key.

encoding data type

• Strings: int, embstr, raw
• Lists: before version 3.2.0 ziplist (small lists), linkedlist
  From version 3.2.0 unified as a single quicklist.
• Sets: intset(integers and small sets), hashtable
• Sorted Sets: ziplist(small zsets), skiplist
• Hashes: ziplist(small hashes), hashtable

Strings data type : int(integer), embstr(small string), raw

• int: indicates the value is an integer. Integers with a decimal point are classified as string. If the number starts with 0 it is a string. For example 123 is int and 0123 is embstr.
• embstr: indicates the value is a string of 44 characters or less. embedded string; embstr is shown from 3.0. Earlier versions showed raw.
• raw: indicates the value is a string of 45 characters or more.

Lists data type : ziplist(small lists), linkedlist

• ziplist: used when there are up to 512 members or the value length is up to 64.
• linkedlist: used when there are 513 or more members or the value length is 65 or more.
• This can be set in redis.conf with list-max-ziplist-entries 512, list-max-ziplist-value 64.
• Before Redis version 3.2.0 these two encoding types were used; from 3.2.0 they are combined into a single quicklist.

Sets: intset(integers and small sets), hashtable

• intset: used when all values are integers and there are up to 512 members. If a value starts with 0 or includes a decimal point, it is converted to hashtable.
• hashtable: used when the value is a string, or there are 513 or more members.
• This can be set in redis.conf with set-max-intset-entries 512.

Sorted Sets: ziplist(small zsets), skiplist

• ziplist: used when there are up to 128 members or the value length is up to 64.
• skiplist: used when there are 129 or more members or the value length is 65 or more.
• This can be set in redis.conf with zset-max-ziplist-entries 128, zset-max-ziplist-value 64.

Hashes: ziplist(small hashes), hashtable

• ziplist: used when there are up to 512 members or the value length is up to 64.
• hashtable: used when there are 513 or more members or the value length is 65 or more.
• This can be set in redis.conf with hash-max-ziplist-entries 512, hash-max-ziplist-value 64.

Syntax

OBJECT encoding key

• Available since version 2.2.3.
• Time complexity is O(1)