Programmability

• Lua scripts no longer have access to the print() function (#10651) - The print function was removed from Lua because it can potentially cause the Redis processes to get stuck (if no one reads from stdout). Users should use redis.log. An alternative is to override the print implementation and print the message to the log file.

• Block PFCOUNT and PUBLISH in read-only scripts (*_RO commands, no-writes) (#10744) - Consider PFCOUNT and PUBLISH as write commands in scripts, in addition to EVAL; meaning:

  • They can never be used in scripts with shebang (#!) and no no-writes flag
  • They are blocked in EVAL_RO and _RO variants, (even in scripts without shebang (#!) flags)
  • Allow no-write scripts in EVAL (not just in EVAL_RO), even during CLIENT PAUSE WRITE

• Hide the may_replicate flag from the COMMAND command response (#10744) - As part of the change to treat may_replicate commands PFCOUNT and PUBLISH as write commands in scripts, in addition to EVAL, the may_replicate flag has been removed from the COMMAND response.

Error handling

• Rephrased some error responses about invalid commands or arguments (#10612) -

  • Error response for unknown command introduced a case change (Unknown to unknown)
  • Errors for module commands extended to cover subcommands, updated syntax to match Redis Server syntax
  • Arity errors for module commands introduce a case change (Wrong to wrong); will consider full command name

• Corrected error codes returned from EVAL scripts (#10218, #10329).

  These examples show changes in behavior:

    1: config set maxmemory 1
    2: +OK
    3: eval "return redis.call('set','x','y')" 0
  - 4: -ERR Error running script (call to 71e6319f97b0fe8bdfa1c5df3ce4489946dda479): @user_script:1: @user_script: 1: -OOM command not allowed when used memory > 'maxmemory'.
  + 4: -ERR Error running script (call to 71e6319f97b0fe8bdfa1c5df3ce4489946dda479): @user_script:1: OOM command not allowed when used memory > 'maxmemory'.
    5: eval "return redis.pcall('set','x','y')" 0
  - 6: -@user_script: 1: -OOM command not allowed when used memory > 'maxmemory'.
  + 6: -OOM command not allowed when used memory > 'maxmemory'.
    7: eval "return redis.call('select',99)" 0
    8: -ERR Error running script (call to 4ad5abfc50bbccb484223905f9a16f09cd043ba8): @user_script:1: ERR DB index is out of range
    9: eval "return redis.pcall('select',99)" 0
   10: -ERR DB index is out of range
   11: eval_ro "return redis.call('set','x','y')" 0
  -12: -ERR Error running script (call to 71e6319f97b0fe8bdfa1c5df3ce4489946dda479): @user_script:1: @user_script: 1: Write commands are not allowed from read-only scripts.
  +12: -ERR Error running script (call to 71e6319f97b0fe8bdfa1c5df3ce4489946dda479): @user_script:1: ERR Write commands are not allowed from read-only scripts.
   13: eval_ro "return redis.pcall('set','x','y')" 0
  -14: -@user_script: 1: Write commands are not allowed from read-only scripts.
  +14: -ERR Write commands are not allowed from read-only scripts.
  

• ZPOPMIN/ZPOPMAX used to produce wrong replies when count is 0 with non-zset #9711):

  • ZPOPMIN/ZPOPMAX used to produce an (empty array) when key was not a sorted set and the optional count argument was set to 0 and now produces a WRONGTYPE error response instead.
  • The optional count argument must be positive. A negative value produces a value is out of range error.

  These examples show changes in behavior:

    1: zadd myzset 1 "one"
    2: (integer) 1
    3: zadd myzset 2 "two"
    4: (integer) 1
    5: zadd myzset 3 "three"
    6: (integer) 1
    7: zpopmin myzset -1
  - 8: (empty array)
  + 8: (error) ERR value is out of range, must be positive
    9: 127.0.0.1:6379> set foo bar
   10: OK
   11: zpopmin foo 0
  -12: (empty array)
  +12: (error) WRONGTYPE Operation against a key holding the wrong kind of value
  

• LPOP/RPOP with count against a nonexistent list returns a null array instead of (nil)(#10095). This change was backported to 6.2.

• LPOP/RPOP used to produce (nil) when count is 0, now produces a null array (#9692). This change was backported to 6.2.

• XCLAIM/XAUTOCLAIM skips deleted entries instead of replying with nil and deletes them from the pending entry list (#10227) - XCLAIM/XAUTOCLAIM now behaves in the following way:

  • If you try to claim a deleted entry, it is deleted from the pending entry list (PEL) where it is found (as well as the group PEL). Therefore, such an entry is not claimed, just cleared from PEL (because it doesn't exist in the stream anyway).
  • Because deleted entries are not claimed, X[AUTO]CLAIM does not return "nil" instead of an entry.
  • Added an array of all the deleted stream IDs to XAUTOCLAIM response.