Collecting slow search queries

The solr_slow_sub_query_log_options performance object reports distributed sub-queries (query executions on individual shards) that take longer than a specified period of time.

All objects are disabled by default.

Procedure

To identify slow search queries using the DataStax Enterprise Performance Service:

To permanently enable and configure collecting information on slow search queries, edit the dse.yaml file and uncomment the solr_slow_sub_query_log_options parameters, and define values for the CQL slow log settings:

solr_slow_sub_query_log_options:
    enabled:true
    ttl_seconds: 604800
    async_writers: 1
    threshold_ms: 100

The default parameter values minimize resource usage.

Options	Determines
enabled	Whether the object is enabled at start up.
ttl_seconds	How many seconds a record survives before it is expired from the performance object.
async_writers	For event-driven objects, such as the slow log, determines the number of possible concurrent slow query recordings. Objects like solr_result_cache_stats are updated in the background.
threshold_ms	For the slow log, the level (in milliseconds) at which a sub-query slow enough to be reported.

Options

Determines

enabled

Whether the object is enabled at start up.

ttl_seconds

How many seconds a record survives before it is expired from the performance object.

async_writers

For event-driven objects, such as the slow log, determines the number of possible concurrent slow query recordings. Objects like solr_result_cache_stats are updated in the background.

threshold_ms

For the slow log, the level (in milliseconds) at which a sub-query slow enough to be reported.

To temporarily change the running parameters for collecting information on slow Solr queries:

To temporarily enable collecting information:
```
dsetool perf solrslowlog enable
```
To temporarily disable collecting information:
```
dsetool perf solrslowlog disable
```
To temporarily change the threshold value in milliseconds:
```
dsetool perf solrslowlog 200
```

You can export slow search queries using the CQL COPY TO command:

cqlsh:dse_perf> COPY solr_slow_sub_query_log ( date, commands, duration ) TO 'slow_solr_queries.csv' WITH HEADER = true;

Collecting slow search queries

Procedure

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