--- weight: 7 title: How to delete or replace metrics in VictoriaMetrics menu: docs: parent: "guides" weight: 7 aliases: - /guides/guide-delete-or-replace-metrics.html --- # How to delete or replace metrics in VictoriaMetrics Data deletion is an operation people expect a database to have. [VictoriaMetrics](https://victoriametrics.com) supports [delete operation](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-delete-time-series) but to a limited extent. Due to implementation details, VictoriaMetrics remains an [append-only database](https://en.wikipedia.org/wiki/Append-only), which perfectly fits the case for storing time series data. But the drawback of such architecture is that it is extremely expensive to mutate the data. Hence, `delete` or `update` operations support is very limited. In this guide, we'll walk through the possible workarounds for deleting or changing already written data in VictoriaMetrics. ### Precondition - [Single-node VictoriaMetrics](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html); - [Cluster version of VictoriaMetrics](https://docs.victoriametrics.com/cluster-victoriametrics/); - [curl](https://curl.se/docs/manual.html) - [jq tool](https://stedolan.github.io/jq/) ## How to delete metrics _Warning: time series deletion is not recommended to use on a regular basis. Each call to delete API could have a performance penalty. The API was provided for one-off operations to deleting malformed data or to satisfy GDPR compliance._ [Delete API](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-delete-time-series) expects from user to specify [time series selector](https://prometheus.io/docs/prometheus/latest/querying/basics/#time-series-selectors). So the first thing to do before the deletion is to verify whether the selector matches the correct series. To check that metrics are present in **VictoriaMetrics Cluster** run the following command: _Warning: response can return many metrics, so be careful with series selector._ ```curl curl -s 'http://vmselect:8481/select/0/prometheus/api/v1/series?match[]=process_cpu_cores_available' | jq ``` The expected output: ```json { "status": "success", "isPartial": false, "data": [ { "__name__": "process_cpu_cores_available", "job": "vmagent", "instance": "vmagent:8429" }, { "__name__": "process_cpu_cores_available", "job": "vmalert", "instance": "vmalert:8880" }, { "__name__": "process_cpu_cores_available", "job": "vminsert", "instance": "vminsert:8480" }, { "__name__": "process_cpu_cores_available", "job": "vmselect", "instance": "vmselect:8481" }, { "__name__": "process_cpu_cores_available", "job": "vmstorage", "instance": "vmstorage-1:8482" }, { "__name__": "process_cpu_cores_available", "job": "vmstorage", "instance": "vmstorage-2:8482" } ] } ``` When you're sure [time series selector](https://prometheus.io/docs/prometheus/latest/querying/basics/#time-series-selectors) is correct, send a POST request to [delete API](https://docs.victoriametrics.com/url-examples.html#apiv1admintsdbdelete_series) with [`match[]=<time-series-selector>`](https://prometheus.io/docs/prometheus/latest/querying/basics/#time-series-selectors) argument. For example: ```curl curl -s 'http://vmselect:8481/delete/0/prometheus/api/v1/admin/tsdb/delete_series?match[]=process_cpu_cores_available' ``` If operation was successful, the deleted series will stop being [queryable](https://docs.victoriametrics.com/keyconcepts/#query-data). Storage space for the deleted time series isn't freed instantly - it is freed during subsequent [background merges of data files](https://medium.com/@valyala/how-victoriametrics-makes-instant-snapshots-for-multi-terabyte-time-series-data-e1f3fb0e0282). The background merges may never occur for data from previous months, so storage space won't be freed for historical data. In this case [forced merge](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#forced-merge) may help freeing up storage space. To trigger [forced merge](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#forced-merge) on VictoriaMetrics Cluster run the following command: ```curl curl -v -X POST http://vmstorage:8482/internal/force_merge ``` After the merge is complete, the data will be permanently deleted from the disk. ## How to update metrics By default, VictoriaMetrics doesn't provide a mechanism for replacing or updating data. As a workaround, take the following actions: - [export time series to a file](https://docs.victoriametrics.com/url-examples.html#apiv1export); - change the values of time series in the file and save it; - [delete time series from a database](https://docs.victoriametrics.com/url-examples.html#apiv1admintsdbdelete_series); - [import saved file to VictoriaMetrics](https://docs.victoriametrics.com/url-examples.html#apiv1import). ### Export metrics For example, let's export metric for `node_memory_MemTotal_bytes` with labels `instance="node-exporter:9100"` and `job="hostname.com"`: ```curl curl -X POST -g http://vmselect:8481/select/0/prometheus/api/v1/export -d 'match[]=node_memory_MemTotal_bytes{instance="node-exporter:9100", job="hostname.com"}' > data.jsonl ``` To check that exported file contains time series we can use [cat](https://man7.org/linux/man-pages/man1/cat.1.html) and [jq](https://stedolan.github.io/jq/download/) ```curl cat data.jsonl | jq ``` The expected output will look like: ```json { "metric": { "__name__": "node_memory_MemTotal_bytes", "job": "hostname.com", "instance": "node-exporter:9100" }, "values": [ 33604390912, 33604390912, 33604390912, 33604390912 ], "timestamps": [ 1656669031378, 1656669032378, 1656669033378, 1656669034378 ] } ``` In this example, we will replace the values of `node_memory_MemTotal_bytes` from `33604390912` to `17179869184` (from 32Gb to 16Gb) via [sed](https://linux.die.net/man/1/sed), but it can be done in any of the available ways. ```sh sed -i 's/33604390912/17179869184/g' data.jsonl ``` Let's check the changes in data.jsonl with `cat`: ```sh cat data.jsonl | jq ``` The expected output will be the next: ```json { "metric": { "__name__": "node_memory_MemTotal_bytes", "job": "hostname.com", "instance": "node-exporter:9100" }, "values": [ 17179869184, 17179869184, 17179869184, 17179869184 ], "timestamps": [ 1656669031378, 1656669032378, 1656669033378, 1656669034378 ] } ``` ### Delete metrics See [How-to-delete-metrics](https://docs.victoriametrics.com/guides/guide-delete-or-replace-metrics.html#how-to-delete-metrics) from the previous paragraph ### Import metrics Victoriametrics supports a lot of [ingestion protocols](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-time-series-data) and we will use [import from JSON line format](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-data-in-json-line-format). The next command will import metrics from `data.jsonl` to VictoriaMetrics: ```curl curl -v -X POST http://vminsert:8480/insert/0/prometheus/api/v1/import -T data.jsonl ``` ### Check imported metrics ```curk curl -X POST -g http://vmselect:8481/select/0/prometheus/api/v1/export -d match[]=node_memory_MemTotal_bytes ``` The expected output will look like: ```json { "metric": { "__name__": "node_memory_MemTotal_bytes", "job": "hostname.com", "instance": "node-exporter:9100" }, "values": [ 17179869184, 17179869184, 17179869184, 17179869184 ], "timestamps": [ 1656669031378, 1656669032378, 1656669033378, 1656669034378 ] } ```