{
  "schema_version": 2,
  "id": "commands/topk.reserve",
  "title": "TOPK.RESERVE",
  "url": "https://redis.io/docs/latest/commands/topk.reserve/",
  "summary": "Initializes a Top-K sketch with specified parameters",
  "since": "2.0.0",
  "tags": [
    "docs",
    "develop",
    "stack",
    "oss",
    "rs",
    "rc",
    "oss",
    "kubernetes",
    "clients"
  ],
  "last_updated": "2026-09-18T09:48:54+01:00",
  "page_type": "content",
  "content_hash": "fd9bca5d41c3420fca75ab309f9b8b3f0287491afc1caeedadd0a2f17f0919a7",
  "sections": [
    {
      "id": "overview",
      "title": "Overview",
      "role": "overview",
      "text": "Initializes a Top-K sketch with specified parameters."
    },
    {
      "id": "required-arguments",
      "title": "Required arguments",
      "role": "content",
      "text": "<details open><summary><code>key</code></summary>\n\nthe name of the Top-k sketch.\n\n</details>\n\n<details open><summary><code>topk</code></summary>\n\nthe number of top (k) occurring items to keep.\n\n</details>"
    },
    {
      "id": "optional-arguments",
      "title": "Optional arguments",
      "role": "parameters",
      "text": "<details open><summary><code>width</code></summary>\n\nNumber of counters kept in each array. (Default 8)\n\n</details>\n\n<details open><summary><code>depth</code></summary>\n\nNumber of arrays. (Default 7)\n\n</details>\n\n<details open><summary><code>decay</code></summary>\n\nThe probability of reducing a counter in an occupied bucket (decay ^ bucket[i].counter). As the counter gets higher, the likelihood of a reduction is lower. (Default 0.9)\n\n</details>"
    },
    {
      "id": "examples",
      "title": "Examples",
      "role": "example",
      "text": "[code example]"
    },
    {
      "id": "redis-software-and-redis-cloud-compatibility",
      "title": "Redis Software and Redis Cloud compatibility",
      "role": "content",
      "text": "| Redis<br />Software | Redis<br />Cloud | <span style=\"min-width: 9em; display: table-cell\">Notes</span> |\n|:----------------------|:-----------------|:------|\n| <span title=\"Supported\">&#x2705; Supported</span><br /> | <span title=\"Supported\">&#x2705; Flexible & Annual</span><br /><span title=\"Supported\">&#x2705; Free & Fixed</nobr></span> |  |"
    },
    {
      "id": "return-information",
      "title": "Return information",
      "role": "returns",
      "text": "**RESP2:**\n\nOne of the following:\n\n* [Simple string reply](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-strings) `OK` if executed correctly.\n* [Simple error reply](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-errors) in these cases: incorrect number of arguments, invalid decay value, or key already exists.\n\n**RESP3:**\n\nOne of the following:\n\n* [Simple string reply](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-strings) `OK` if executed correctly.\n* [Simple error reply](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-errors) in these cases: incorrect number of arguments, invalid decay value, or key already exists."
    }
  ],
  "examples": [
    {
      "id": "examples-ex0",
      "language": "plaintext",
      "code": "redis> TOPK.RESERVE topk 50 2000 7 0.925\nOK",
      "section_id": "examples"
    }
  ]
}