Increment the floating point value of a key by a number. Uses 0 as initial value if the key doesn’t exist.
INCRBYFLOAT
key
increment
Increment the string representing a floating point number stored at
key
by the specified increment
. By using a
negative increment
value, the result is that the value
stored at the key is decremented (by the obvious properties of
addition). If the key does not exist, it is set to 0
before
performing the operation. An error is returned if one of the following
conditions occur:
If the command is successful the new incremented value is stored as the new value of the key (replacing the old one), and returned to the caller as a string.
Both the value already contained in the string key and the increment argument can be optionally provided in exponential notation, however the value computed after the increment is stored consistently in the same format, that is, an integer number followed (if needed) by a dot, and a variable number of digits representing the decimal part of the number. Trailing zeroes are always removed.
The precision of the output is fixed at 17 digits after the decimal point regardless of the actual internal precision of the computation.
Bulk string reply: the value of the key after the increment.
O(1)
@fast @string @write
127.0.0.1:6379> SET mykey 10.50
OK
127.0.0.1:6379> INCRBYFLOAT mykey 0.1
"10.6"
127.0.0.1:6379> INCRBYFLOAT mykey -5
"5.6"
127.0.0.1:6379> SET mykey 5.0e3
OK
127.0.0.1:6379> INCRBYFLOAT mykey 2.0e2
"5200"
The command is always propagated in the replication link and the
Append Only File as a SET
operation, so that differences in
the underlying floating point math implementation will not be sources of
inconsistency.
APPEND, DECR, DECRBY, GET, GETDEL, GETEX, GETRANGE, INCR, INCRBY, LCS, MGET, MSET, MSETNX, SET, SETRANGE, STRLEN.