[[index-modules-slowlog]] == Slow Log [float] [[search-slow-log]] === Search Slow Log Shard level slow search log allows to log slow search (query and fetch phases) into a dedicated log file. Thresholds can be set for both the query phase of the execution, and fetch phase, here is a sample: [source,yaml] -------------------------------------------------- index.search.slowlog.threshold.query.warn: 10s index.search.slowlog.threshold.query.info: 5s index.search.slowlog.threshold.query.debug: 2s index.search.slowlog.threshold.query.trace: 500ms index.search.slowlog.threshold.fetch.warn: 1s index.search.slowlog.threshold.fetch.info: 800ms index.search.slowlog.threshold.fetch.debug: 500ms index.search.slowlog.threshold.fetch.trace: 200ms index.search.slowlog.level: info -------------------------------------------------- All of the above settings are _dynamic_ and can be set for each index using the <> API. For example: [source,console] -------------------------------------------------- PUT /twitter/_settings { "index.search.slowlog.threshold.query.warn": "10s", "index.search.slowlog.threshold.query.info": "5s", "index.search.slowlog.threshold.query.debug": "2s", "index.search.slowlog.threshold.query.trace": "500ms", "index.search.slowlog.threshold.fetch.warn": "1s", "index.search.slowlog.threshold.fetch.info": "800ms", "index.search.slowlog.threshold.fetch.debug": "500ms", "index.search.slowlog.threshold.fetch.trace": "200ms", "index.search.slowlog.level": "info" } -------------------------------------------------- // TEST[setup:twitter] By default, none are enabled (set to `-1`). Levels (`warn`, `info`, `debug`, `trace`) allow to control under which logging level the log will be logged. Not all are required to be configured (for example, only `warn` threshold can be set). The benefit of several levels is the ability to quickly "grep" for specific thresholds breached. The logging is done on the shard level scope, meaning the execution of a search request within a specific shard. It does not encompass the whole search request, which can be broadcast to several shards in order to execute. Some of the benefits of shard level logging is the association of the actual execution on the specific machine, compared with request level. The logging file is configured by default using the following configuration (found in `log4j2.properties`): [source,properties] -------------------------------------------------- appender.index_search_slowlog_rolling.type = RollingFile appender.index_search_slowlog_rolling.name = index_search_slowlog_rolling appender.index_search_slowlog_rolling.fileName = ${sys:es.logs.base_path}${sys:file.separator}${sys:es.logs.cluster_name}_index_search_slowlog.log appender.index_search_slowlog_rolling.layout.type = PatternLayout appender.index_search_slowlog_rolling.layout.pattern = [%d{ISO8601}][%-5p][%-25c] [%node_name]%marker %.-10000m%n appender.index_search_slowlog_rolling.filePattern = ${sys:es.logs.base_path}${sys:file.separator}${sys:es.logs.cluster_name}_index_search_slowlog-%i.log.gz appender.index_search_slowlog_rolling.policies.type = Policies appender.index_search_slowlog_rolling.policies.size.type = SizeBasedTriggeringPolicy appender.index_search_slowlog_rolling.policies.size.size = 1GB appender.index_search_slowlog_rolling.strategy.type = DefaultRolloverStrategy appender.index_search_slowlog_rolling.strategy.max = 4 logger.index_search_slowlog_rolling.name = index.search.slowlog logger.index_search_slowlog_rolling.level = trace logger.index_search_slowlog_rolling.appenderRef.index_search_slowlog_rolling.ref = index_search_slowlog_rolling logger.index_search_slowlog_rolling.additivity = false -------------------------------------------------- [float] ==== Identifying search slow log origin It is often useful to identify what triggered a slow running query. If a call was initiated with an `X-Opaque-ID` header, then the user ID is included in Search Slow logs as an additional **id** field (scroll to the right). [source,txt] --------------------------- [2030-08-30T11:59:37,786][WARN ][i.s.s.query ] [node-0] [index6][0] took[78.4micros], took_millis[0], total_hits[0 hits], stats[], search_type[QUERY_THEN_FETCH], total_shards[1], source[{"query":{"match_all":{"boost":1.0}}}], id[MY_USER_ID], --------------------------- // NOTCONSOLE The user ID is also included in JSON logs. [source,js] --------------------------- { "type": "index_search_slowlog", "timestamp": "2030-08-30T11:59:37,786+02:00", "level": "WARN", "component": "i.s.s.query", "cluster.name": "distribution_run", "node.name": "node-0", "message": "[index6][0]", "took": "78.4micros", "took_millis": "0", "total_hits": "0 hits", "stats": "[]", "search_type": "QUERY_THEN_FETCH", "total_shards": "1", "source": "{\"query\":{\"match_all\":{\"boost\":1.0}}}", "id": "MY_USER_ID", "cluster.uuid": "Aq-c-PAeQiK3tfBYtig9Bw", "node.id": "D7fUYfnfTLa2D7y-xw6tZg" } --------------------------- // NOTCONSOLE [float] [[index-slow-log]] === Index Slow log The indexing slow log, similar in functionality to the search slow log. The log file name ends with `_index_indexing_slowlog.log`. Log and the thresholds are configured in the same way as the search slowlog. Index slowlog sample: [source,yaml] -------------------------------------------------- index.indexing.slowlog.threshold.index.warn: 10s index.indexing.slowlog.threshold.index.info: 5s index.indexing.slowlog.threshold.index.debug: 2s index.indexing.slowlog.threshold.index.trace: 500ms index.indexing.slowlog.level: info index.indexing.slowlog.source: 1000 -------------------------------------------------- All of the above settings are _dynamic_ and can be set for each index using the <> API. For example: [source,console] -------------------------------------------------- PUT /twitter/_settings { "index.indexing.slowlog.threshold.index.warn": "10s", "index.indexing.slowlog.threshold.index.info": "5s", "index.indexing.slowlog.threshold.index.debug": "2s", "index.indexing.slowlog.threshold.index.trace": "500ms", "index.indexing.slowlog.level": "info", "index.indexing.slowlog.source": "1000" } -------------------------------------------------- // TEST[setup:twitter] By default Elasticsearch will log the first 1000 characters of the _source in the slowlog. You can change that with `index.indexing.slowlog.source`. Setting it to `false` or `0` will skip logging the source entirely an setting it to `true` will log the entire source regardless of size. The original `_source` is reformatted by default to make sure that it fits on a single log line. If preserving the original document format is important, you can turn off reformatting by setting `index.indexing.slowlog.reformat` to `false`, which will cause the source to be logged "as is" and can potentially span multiple log lines. The index slow log file is configured by default in the `log4j2.properties` file: [source,properties] -------------------------------------------------- appender.index_indexing_slowlog_rolling.type = RollingFile appender.index_indexing_slowlog_rolling.name = index_indexing_slowlog_rolling appender.index_indexing_slowlog_rolling.fileName = ${sys:es.logs.base_path}${sys:file.separator}${sys:es.logs.cluster_name}_index_indexing_slowlog.log appender.index_indexing_slowlog_rolling.layout.type = PatternLayout appender.index_indexing_slowlog_rolling.layout.pattern = [%d{ISO8601}][%-5p][%-25c] [%node_name]%marker %.-10000m%n appender.index_indexing_slowlog_rolling.filePattern = ${sys:es.logs.base_path}${sys:file.separator}${sys:es.logs.cluster_name}_index_indexing_slowlog-%i.log.gz appender.index_indexing_slowlog_rolling.policies.type = Policies appender.index_indexing_slowlog_rolling.policies.size.type = SizeBasedTriggeringPolicy appender.index_indexing_slowlog_rolling.policies.size.size = 1GB appender.index_indexing_slowlog_rolling.strategy.type = DefaultRolloverStrategy appender.index_indexing_slowlog_rolling.strategy.max = 4 logger.index_indexing_slowlog.name = index.indexing.slowlog.index logger.index_indexing_slowlog.level = trace logger.index_indexing_slowlog.appenderRef.index_indexing_slowlog_rolling.ref = index_indexing_slowlog_rolling logger.index_indexing_slowlog.additivity = false --------------------------------------------------