Engine specific parameters - Amazon MemoryDB (original) (raw)
If you do not specify a parameter group for your Valkey or Redis OSS cluster, then a default parameter group appropriate to your engine version will be used. You can't change the values of any parameters in the default parameter group. However, you can create a custom parameter group and assign it to your cluster at any time as long as the values of conditionally modifiable parameters are the same in both parameter groups. For more information, see Creating a parameter group.
Note
MemoryDB introduced Vector search that includes a new immutable parameter groupdefault.memorydb-valkey7.search. This parameter group is available in the MemoryDB console and when creating a new vector-search-enabled cluster using the create-cluster CLI command. The preview release is available in the following AWS Regions: US East (N. Virginia), US East (Ohio), US West (Oregon), Asia Pacific (Tokyo), and Europe (Ireland).
Parameters added in Valkey 7 and Redis OSS 7 are as follows.
| Name | Details | Description |
|---|---|---|
| latency-tracking | Permitted values: yes, no Default: no Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | When set to yes tracks the per command latencies and enables exporting the percentile distribution via theINFO latency statistics command, and cumulative latency distributions (histograms) via the LATENCY command. |
| hash-max-listpack-entries | Permitted values: 0+ Default: 512 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | The maximum number of hash entries in order for the dataset to be compressed. |
| hash-max-listpack-value | Permitted values: 0+ Default: 64 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | The threshold of biggest hash entries in order for the dataset to be compressed. |
| zset-max-listpack-entries | Permitted values: 0+ Default: 128 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | The maximum number of sorted set entries in order for the dataset to be compressed. |
| zset-max-listpack-value | Permitted values: 0+ Default: 64 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | The threshold of biggest sorted set entries in order for the dataset to be compressed. |
| search-enabled | Permitted values: yes, no Default: no Type: string Modifiable: Yes Changes take effect: For new clusters only. Minimum engine version: 7.1 | When set to yes, it enables the Search capabilities. |
| search-query-timeout-ms | Permitted values: 1 - 60,000 Default: 10,000 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. Minimum engine version: 7.1 | The maximum amount of time in milliseconds that a search query is allowed to run. |
Parameters changed in Redis OSS 7 are as follows.
| Name | Details | Description |
|---|---|---|
| activerehashing | Modifiable: no. In Redis OSS 7, this parameter is hidden and enabled by default. In order to disable it, you need to create a support case. | Modifiable was yes. |
Parameters removed in Redis OSS 7 are as follows.
| Name | Details | Description |
|---|---|---|
| hash-max-ziplist-entries | Permitted values: 0+ Default: 512 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | Use listpack instead of ziplist for representing small hash encoding |
| hash-max-ziplist-value | Permitted values: 0+ Default: 64 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | Use listpack instead of ziplist for representing small hash encoding |
| zset-max-ziplist-entries | Permitted values: 0+ Default: 128 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | Use listpack instead of ziplist for representing small hash encoding. |
| zset-max-ziplist-value | Permitted values: 0+ Default: 64 Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster. | Use listpack instead of ziplist for representing small hash encoding. |
Note
In Redis OSS engine version 6.2, when the r6gd node family was introduced for use with Data tiering, only noeviction, volatile-lru and allkeys-lru max-memory policies are supported with r6gd node types.
Parameters added in Redis OSS 6 are as follows.
| Name | Details | Description |
|---|---|---|
| maxmemory-policy | Type: STRING Permitted values: volatile-lru,allkeys-lru,volatile-lfu,allkeys-lfu,volatile-random,allkeys-random,volatile-ttl,noeviction Default: noeviction | The eviction policy for keys when maximum memory usage is reached.For more information, see Using Redis OSS as an LRU cache Using Redis OSS as an LRU cache. |
| list-compress-depth | Type: INTEGER Permitted values: 0- Default: 0 | Compress depth is the number of quicklist ziplist nodes from each side of the list to exclude from compression. The head and tail of the list are always uncompressed for fast push and pop operations. Settings are: 0: Disable all compression.1: Start compressing with the 1st node in from the head and tail. [head]->node->node->...->node->[tail] All nodes except [head] and [tail] compress.2: Start compressing with the 2nd node in from the head and tail. [head]->[next]->node->node->...->node->[prev]->[tail] [head], [next], [prev], [tail] do not compress. All other nodes compress.Etc. |
| hll-sparse-max-bytes | Type: INTEGER Permitted values: 1-16000 Default: 3000 | HyperLogLog sparse representation bytes limit. The limit includes the 16 byte header. When a HyperLogLog using the sparse representation crosses this limit, it is converted into the dense representation. A value greater than 16000 is not recommended, because at that point the dense representation is more memory efficient. We recommend a value of about 3000 to have the benefits of the space-efficient encoding without slowing down PFADD too much, which is O(N) with the sparse encoding. The value can be raised to ~10000 when CPU is not a concern, but space is, and the data set is composed of many HyperLogLogs with cardinality in the 0 - 15000 range. |
| lfu-log-factor | Type: INTEGER Permitted values: 1- Default: 10 | The log factor for incrementing key counter for LFU eviction policy. |
| lfu-decay-time | Type: INTEGER Permitted values: 0- Default: 1 | The amount of time in minutes to decrement the key counter for LFU eviction policy. |
| active-defrag-max-scan-fields | Type: INTEGER Permitted values: 1-1000000 Default: 1000 | Maximum number of set/hash/zset/list fields that will be processed from the main dictionary scan during active defragmentation. |
| active-defrag-threshold-upper | Type: INTEGER Permitted values: 1-100 Default: 100 | Maximum percentage of fragmentation at which we use maximum effort. |
| client-output-buffer-limit-pubsub-hard-limit | Type: INTEGER Permitted values: 0- Default: 33554432 | For Redis OSS publish/subscribe clients: If a client's output buffer reaches the specified number of bytes, the client will be disconnected. |
| client-output-buffer-limit-pubsub-soft-limit | Type: INTEGER Permitted values: 0- Default: 8388608 | For Redis OSS publish/subscribe clients: If a client's output buffer reaches the specified number of bytes, the client will be disconnected, but only if this condition persists for client-output-buffer-limit-pubsub-soft-seconds. |
| client-output-buffer-limit-pubsub-soft-seconds | Type: INTEGER Permitted values: 0- Default: 60 | For Redis OSS publish/subscribe clients: If a client's output buffer remains at client-output-buffer-limit-pubsub-soft-limit bytes for longer than this number of seconds, the client will be disconnected. |
| timeout | Type: INTEGER Permitted values: 0,20- Default: 0 | The number of seconds a node waits before timing out. Values are: 0 – never disconnect an idle client.1-19 – invalid values.>=20 – the number of seconds a node waits before disconnecting an idle client. |
| notify-keyspace-events | Type: STRING Permitted values: NULL Default: NULL | The keyspace events for Redis OSS to notify Pub/Sub clients about. By default all notifications are disabled. |
| maxmemory-samples | Type: INTEGER Permitted values: 1- Default: 3 | For least-recently-used (LRU) and time-to-live (TTL) calculations, this parameter represents the sample size of keys to check. By default, Redis OSS chooses 3 keys and uses the one that was used least recently. |
| slowlog-max-len | Type: INTEGER Permitted values: 0- Default: 128 | The maximum length of the Redis OSS Slow Log. There is no limit to this length. Just be aware that it will consume memory. You can reclaim memory used by the slow log with SLOWLOG RESET. |
| activerehashing | Type: STRING Permitted values: yes,no Default: yes | The main hash table is rehashed ten times per second; each rehash operation consumes 1 millisecond of CPU time. This value is set when you create the parameter group. When assigning a new parameter group to a cluster, this value must be the same in both the old and new parameter groups. |
| client-output-buffer-limit-normal-hard-limit | Type: INTEGER Permitted values: 0- Default: 0 | If a client's output buffer reaches the specified number of bytes, the client will be disconnected. The default is zero (no hard limit). |
| client-output-buffer-limit-normal-soft-limit | Type: INTEGER Permitted values: 0- Default: 0 | If a client's output buffer reaches the specified number of bytes, the client will be disconnected, but only if this condition persists for client-output-buffer-limit-normal-soft-seconds. The default is zero (no soft limit). |
| client-output-buffer-limit-normal-soft-seconds | Type: INTEGER Permitted values: 0- Default: 0 | If a client's output buffer remains at client-output-buffer-limit-normal-soft-limit bytes for longer than this number of seconds, the client will be disconnected. The default is zero (no time limit). |
| tcp-keepalive | Type: INTEGER Permitted values: 0- Default: 300 | If this is set to a nonzero value (N), node clients are polled every N seconds to ensure that they are still connected. With the default setting of 0, no such polling occurs. |
| active-defrag-cycle-min | Type: INTEGER Permitted values: 1-75 Default: 5 | Minimal effort for defrag in CPU percentage. |
| stream-node-max-bytes | Type: INTEGER Permitted values: 0- Default: 4096 | The stream data structure is a radix tree of nodes that encode multiple items inside. Use this configuration to specify the maximum size of a single node in radix tree in Bytes. If set to 0, the size of the tree node is unlimited. |
| stream-node-max-entries | Type: INTEGER Permitted values: 0- Default: 100 | The stream data structure is a radix tree of nodes that encode multiple items inside. Use this configuration to specify the maximum number of items a single node can contain before switching to a new node when appending new stream entries. If set to 0, the number of items in the tree node is unlimited. |
| lazyfree-lazy-eviction | Type: STRING Permitted values: yes,no Default: no | Perform an asynchronous delete on evictions. |
| active-defrag-ignore-bytes | Type: INTEGER Permitted values: 1048576- Default: 104857600 | Minimum amount of fragmentation waste to start active defrag. |
| lazyfree-lazy-expire | Type: STRING Permitted values: yes,no Default: no | Perform an asynchronous delete on expired keys. |
| active-defrag-threshold-lower | Type: INTEGER Permitted values: 1-100 Default: 10 | Minimum percentage of fragmentation to start active defrag. |
| active-defrag-cycle-max | Type: INTEGER Permitted values: 1-75 Default: 75 | Maximal effort for defrag in CPU percentage. |
| lazyfree-lazy-server-del | Type: STRING Permitted values: yes,no Default: no | Performs an asynchronous delete for commands which update values. |
| slowlog-log-slower-than | Type: INTEGER Permitted values: 0- Default: 10000 | The maximum execution time, in microseconds, to exceed in order for the command to get logged by the Redis OSS Slow Log feature. Note that a negative number disables the slow log, while a value of zero forces the logging of every command. |
| hash-max-ziplist-entries | Type: INTEGER Permitted values: 0- Default: 512 | Determines the amount of memory used for hashes. Hashes with fewer than the specified number of entries are stored using a special encoding that saves space. |
| hash-max-ziplist-value | Type: INTEGER Permitted values: 0- Default: 64 | Determines the amount of memory used for hashes. Hashes with entries that are smaller than the specified number of bytes are stored using a special encoding that saves space. |
| set-max-intset-entries | Type: INTEGER Permitted values: 0- Default: 512 | Determines the amount of memory used for certain kinds of sets (strings that are integers in radix 10 in the range of 64 bit signed integers). Such sets with fewer than the specified number of entries are stored using a special encoding that saves space. |
| zset-max-ziplist-entries | Type: INTEGER Permitted values: 0- Default: 128 | Determines the amount of memory used for sorted sets. Sorted sets with fewer than the specified number of elements are stored using a special encoding that saves space. |
| zset-max-ziplist-value | Type: INTEGER Permitted values: 0- Default: 64 | Determines the amount of memory used for sorted sets. Sorted sets with entries that are smaller than the specified number of bytes are stored using a special encoding that saves space. |
| tracking-table-max-keys | Type: INTEGER Permitted values: 1-100000000 Default: 1000000 | To assist client-side caching, Redis OSS supports tracking which clients have accessed which keys. When the tracked key is modified, invalidation messages are sent to all clients to notify them their cached values are no longer valid. This value enables you to specify the upper bound of this table. |
| acllog-max-len | Type: INTEGER Permitted values: 1-10000 Default: 128 | The maximum number of entries in the ACL Log. |
| active-expire-effort | Type: INTEGER Permitted values: 1-10 Default: 1 | Redis OSS deletes keys that have exceeded their time to live by two mechanisms. In one, a key is accessed and is found to be expired. In the other, a periodic job samples keys and causes those that have exceeded their time to live to expire. This parameter defines the amount of effort that Redis OSS uses to expire items in the periodic job. The default value of 1 tries to avoid having more than 10 percent of expired keys still in memory. It also tries to avoid consuming more than 25 percent of total memory and to add latency to the system. You can increase this value up to 10 to increase the amount of effort spent on expiring keys. The tradeoff is higher CPU and potentially higher latency. We recommend a value of 1 unless you are seeing high memory usage and can tolerate an increase in CPU utilization. |
| lazyfree-lazy-user-del | Type: STRING Permitted values: yes,no Default: no | Specifies whether the default behavior of DEL command acts the same as UNLINK. |
| activedefrag | Type: STRING Permitted values: yes,no Default: no | Enabled active memory defragmentation. |
| maxclients | Type: INTEGER Permitted values: 65000 Default: 65000 | The maximum number of clients that can be connected at one time. Non modifiable. |
| client-query-buffer-limit | Type: INTEGER Permitted values: 1048576-1073741824 Default: 1073741824 | Max size of a single client query buffer. Change takes place immediately. |
| proto-max-bulk-len | Type: INTEGER Permitted values: 1048576-536870912 Default: 536870912 | Max size of a single element request. Change takes place immediately. |
Although most parameters have a single value, some parameters have different values depending on the node type used. The following table shows the default value for the maxmemory for each node type. The value of maxmemory is the maximum number of bytes available to you for use, data and other uses, on the node.