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PFDEBUG

Last updated 
PFDEBUG GETREG key
PFDEBUG DECODE key
PFDEBUG ENCODING key
PFDEBUG TODENSE key
Group
HyperLogLog
Complexity
O(N) where N is the number of registers
Arity
3 (exactly, counting the command name)
Flags
write, admin
Keys
first 2, last 2, step 1
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PFDEBUG is a diagnostic command for HyperLogLog values. A HyperLogLog starts in a compact sparse representation and switches to the fixed-size dense one as it fills up (the switch point is set with hll-sparse-max-bytes). PFDEBUG lets you see which one a key uses and its raw registers. It is an administrative command, meant for debugging rather than application code.

Options

Section titled “Options”
Subcommand Effect
GETREG Return the value of every register. Converts a sparse HyperLogLog to dense first.
DECODE Return a text description of a sparse HyperLogLog’s contents.
ENCODING Return sparse or dense.
TODENSE Convert to dense if the HyperLogLog is sparse.

The subcommand comes before the key and is not case-sensitive.

Return value

Section titled “Return value”
Subcommand RESP2 RESP3
GETREG Array of 16384 integers Array
DECODE Bulk string Bulk string
ENCODING Simple string sparse or dense Simple string
TODENSE Integer 1 if it was converted, 0 if it was already dense Integer

Errors:

  • ERR The specified key does not exist for a missing key.
  • ERR HLL encoding is not sparse for DECODE on a dense HyperLogLog.
  • ERR Unknown PFDEBUG subcommand '<name>' for an unknown subcommand.
  • The WRONGTYPE and INVALIDOBJ errors of PFADD.

Examples

Section titled “Examples”
127.0.0.1:6379> PFADD visitors alice bob carol
(integer) 1
127.0.0.1:6379> PFDEBUG ENCODING visitors
sparse
127.0.0.1:6379> PFDEBUG TODENSE visitors
(integer) 1
127.0.0.1:6379> PFDEBUG ENCODING visitors
dense
127.0.0.1:6379> PFCOUNT visitors
(integer) 3

Compatibility

Section titled “Compatibility”

Same subcommands and replies as Redis 7 and Valkey 8.

See also

Section titled “See also”

PFSELFTEST, PFADD, PFCOUNT