Monitor Queries

      +
      Monitoring and profiling SQL++ queries, query service engines, and corresponding system resources is very important for smoother operational performance and efficiency of the system. In fact, often it is vital for diagnosing and troubleshooting issues such as query performance, resource bottlenecks, and overloading of various services.

      System keyspaces provide various monitoring details and statistics about individual queries and query service. When running on a cluster with multiple query nodes, stats about all queries on all query nodes are collected in these system keyspaces.

      For example, this can help identify:

      • The top 10 slow or fast queries running on a particular query engine or the cluster.

      • Resource usage statistics of the query service, or resources used for a particular query.

      • Details about the active, completed, and prepared queries.

      • Find long running queries that are running for more than 2 minutes.

      These system keyspaces are like virtual keyspaces that are transient in nature, and are not persisted to disk or permanent storage. Hence, the information in the keyspaces pertains to the current instantiation of the query service. You can access the keyspaces using any of the following:

      • SQL++ language (from the cbq shell or Query Workbench)

      • REST API

      • Monitoring SDK

      All the power of the SQL++ query language can be applied on the keyspaces to obtain various insights.

      The following diagnostics are provided:

      System Catalogs

      Monitoring Catalogs

      Security Catalogs

      Other

      These are only available using REST APIs.

      Authentication and Client Privileges

      Client applications must be authenticated with sufficient privileges to access system keyspaces.

      • Users must have the Query System Catalog role to access restricted system keyspaces. For more details about user roles, see Authorization.

      • In addition, users must have permission to access a bucket, scope, or collection to be able to view that item in the system catalog. Similarly, users must have SELECT permission on the target of an index to be able to view that index in the system catalog.

      • The following system keyspaces are considered open, that is, all users can access them without any special privileges:

        • system:dual

        • system:datastores

        • system:namespaces

      Query Monitoring Settings

      The monitoring settings can be set for each query engine (using the REST API) or for each query statement (using the cbq command line tool). Both settings are actually set via REST endpoints: using the Admin REST API (/admin/settings endpoint) and the Query REST API (/query/service endpoint).

      The cbq shell and Query Workbench use the Query REST API to set monitoring at the request level. The Query Workbench automatically enables the profiling and timings. It can be disabled using the Preferences option. For more information refer to the Query Workbench section.

      Use the following query parameters to enable, disable, and control the monitoring capabilities, and the level of monitoring and profiling details for each query or globally at a query engine level:

      • profile

      • controls

      For more details and examples, refer to the Query Settings section.

      Enable Settings for a Query Engine

      You can enable profile settings for each query engine. These examples use local host IP address and default port numbers. You need to provide correct credentials, IP address, and port details of your setup.

      1. Get the current query settings:

        curl http://localhost:8093/admin/settings -u user:pword -o ./query_settings.json
        cat  ./query_settings.json
        {
          "atrcollection": "",
          "auto-prepare": false,
          "cleanupclientattempts": true,
          "cleanuplostattempts": true,
          "cleanupwindow": "1m0s",
          "completed": {
            "aborted": null,
            "threshold": 1000
          },
          "completed-limit": 4000,
          "completed-threshold": 1000,
          "controls": false,
          "cpuprofile": "",
          "debug": false,
          "functions-limit": 16384,
          "keep-alive-length": 16384,
          "loglevel": "INFO",
          "max-index-api": 4,
          "max-parallelism": 1,
          "memory-quota": 0,
          "memprofile": "",
          "mutexprofile": false,
          "n1ql-feat-ctrl": 76,
          "numatrs": 1024,
          "pipeline-batch": 16,
          "pipeline-cap": 512,
          "plus-servicers": 16,
          "prepared-limit": 16384,
          "pretty": false,
          "profile": "off",
          "request-size-cap": 67108864,
          "scan-cap": 512,
          "servicers": 4,
          "timeout": 0,
          "txtimeout": "0s",
          "use-cbo": true
        }
      2. Set current query settings profile:

        1. To set the query settings saved in a file ./query_settings.json, enter the following query:

          curl http://localhost:8093/admin/settings -u user:pword \
            -X POST \
            -d@./query_settings.json
        2. To explicitly specify the settings, enter the following query:

          curl http://localhost:8093/admin/settings -u user:pword \
            -H 'Content-Type: application/json' \
            -d '{"profile": "phases"}'
      3. Verify the settings are changed as specified:

        curl http://localhost:8093/admin/settings -u user:pword
        {
          // ...
          "profile":"phases",
          "request-size-cap": 67108864,
          "scan-cap": 512,
          "servicers": 4,
          "timeout": 0,
          "txtimeout": "0s",
          "use-cbo": true
        }

      Enable Settings per Session or per Query

      You can enable monitoring and profiling settings for each query statement. To set query settings using the cbq shell, use the \SET command:

      \set -profile "timings";
      \set;
       Query Parameters :
       Parameter name : profile
       Value : ["timings"]
       ...

      To set query settings using the REST API, specify the parameters in the request body:

      curl http://localhost:8093/query/service -u user:pword \
        -d 'profile=timings&statement=SELECT * FROM "world" AS hello'

      Monitoring and Profiling Details

      Couchbase Server provides detailed query monitoring and profiling information. The profiling and finer query execution timing details can be obtained for any query.

      When a query executes a user-defined function, profiling information is available for the SQL++ queries within the user-defined function as well.

      Attribute Profile in Query Response

      When profiling is enabled, a query response includes the profile attribute. The attribute details are as follows:

      Table 1. Attribute Details
      Attribute Example

      phaseTimes — Cumulative execution times for various phases involved in the query execution, such as authorize, indexscan, fetch, parse, plan, run, etc.

      This value will be dynamic, depending on the documents processed by various phases up to this moment in time.

      A new query on system:active_requests will return different values.

      "phaseTimes": {
        "authorize": "823.631µs",
        "fetch": "656.873µs",
        "indexScan": "29.146543ms",
        "instantiate": "236.221µs",
        "parse": "826.382µs",
        "plan": "11.831101ms",
        "run": "16.892181ms"
      }

      phaseCounts — Count of documents processed at selective phases involved in the query execution, such as authorize, indexscan, fetch, parse, plan, run, etc.

      This value will be dynamic, depending on the documents processed by various phases up to this moment in time.

      A new query on system:active_requests will return different values.

      "phaseCounts": {
        "fetch": 16,
        "indexScan": 187
      }

      phaseOperators — Indicates the number of each kind of query operators involved in different phases of the query processing. For instance, this example, one non covering index path was taken, which involves 1 indexScan and 1 fetch operator.

      A join would have probably involved 2 fetches (1 per keyspace)

      A union select would have twice as many operator counts (1 per each branch of the union).

      This is in essence the count of all the operators in the executionTimings field.

      "phaseOperators": {
        "authorize": 1,
        "fetch": 1,
        "indexScan": 2
      }

      executionTimings — The execution details such as kernel and service execution times, number of documents processed at each query operator in each phase, and number of phase switches, for various phases involved in the query execution.

      The following statistics are collected for each operator:

      #operator

      Name of the operator.

      #stats

      These values will be dynamic, depending on the documents processed by various phases up to this moment in time.

      A new query on system:active_requests will return different values.

      #itemsIn

      Number of input documents to the operator.

      #itemsOut

      Number of output documents after the operator processing.

      #phaseSwitches

      Number of switches between executing, waiting for services, or waiting for the goroutine scheduler.

      execTime

      Time spent executing the operator code inside SQL++ query engine.

      kernTime

      Time spent waiting to be scheduled for CPU time.

      servTime

      Time spent waiting for another service, such as index or data.

      • For index scan, it is time spent waiting for GSI/indexer.

      • For fetch, it is time spent waiting on the KV store.

      "executionTimings": {
        // …
        [{
          "#operator": "Fetch",
          "#stats": {
            "#itemsIn": 187,
            "#itemsOut": 16,
            "#phaseSwitches": 413,
            "execTime": "128.434µs",
            "kernTime": "15.027879ms",
            "servTime": "1.590934ms",
            "state": "services"
          },
          "keyspace": "travel-sample",
          "namespace": "default"
        },
        {
          "#operator": "IntersectScan",
          "#stats": {
          "#itemsIn": 187,
          "#itemsOut": 187,
          "#phaseSwitches": 749,
          "execTime": "449.944µs",
          "kernTime": "14.625524ms"
          }
        // …
        ]}

      These statistics (kernTime, servTime, and execTime) can be very helpful in troubleshooting query performance issues, such as:

      • A high servTime for a low number of items processed is an indication that the indexer or KV store is stressed.

      • A high kernTime means there is a downstream issue in the query plan or the query server having many requests to process (so the scheduled waiting time will be more for CPU time).

      Example 1. Phases Profile

      The cbq engine must be started with authorization, for example:

      ./cbq -engine=http://localhost:8091/ -u Administrator -p pword

      Using the cbq shell, show the statistics collected when the profile is set to phases:

      \set -profile "phases";
      SELECT * FROM `travel-sample`.inventory.airline LIMIT 1;
      {
        "requestID": "06d6c1c2-1a8a-4989-a856-7314f9eddee5",
        "signature": {
          "*": "*"
        },
        "results": [
          {
            "airline": {
              "callsign": "MILE-AIR",
              "country": "United States",
              "iata": "Q5",
              "icao": "MLA",
              "id": 10,
              "name": "40-Mile Air",
              "type": "airline"
            }
          }
        ],
        "status": "success",
        "metrics": {
          "elapsedTime": "12.77927ms",
          "executionTime": "12.570648ms",
          "resultCount": 1,
          "resultSize": 254,
          "serviceLoad": 12
        },
        "profile": {
          "phaseTimes": {
            "authorize": "19.629µs",
            "fetch": "401.997µs",
            "instantiate": "147.686µs",
            "parse": "4.545234ms",
            "plan": "409.364µs",
            "primaryScan": "6.103775ms",
            "run": "6.699056ms"
          },
          "phaseCounts": {
            "fetch": 1,
            "primaryScan": 1
          },
          "phaseOperators": {
            "authorize": 1,
            "fetch": 1,
            "primaryScan": 1
          },
          "requestTime": "2021-04-30T18:37:56.394Z",
          "servicingHost": "127.0.0.1:8091"
        }
      }
      Example 2. Timings Profile

      Using the cbq shell, show the statistics collected when profile is set to timings:

      \set -profile "timings";
      SELECT * FROM `travel-sample`.inventory.airline LIMIT 1;
      {
        "requestID": "268a1240-6864-43a2-af13-ccb8d1e50abf",
        "signature": {
          "*": "*"
        },
        "results": [
          {
            "airline": {
              "callsign": "MILE-AIR",
              "country": "United States",
              "iata": "Q5",
              "icao": "MLA",
              "id": 10,
              "name": "40-Mile Air",
              "type": "airline"
            }
          }
        ],
        "status": "success",
        "metrics": {
          "elapsedTime": "2.915245ms",
          "executionTime": "2.755355ms",
          "resultCount": 1,
          "resultSize": 254,
          "serviceLoad": 12
        },
        "profile": {
          "phaseTimes": {
            "authorize": "18.096µs",
            "fetch": "388.122µs",
            "instantiate": "31.702µs",
            "parse": "646.157µs",
            "plan": "120.427µs",
            "primaryScan": "1.402918ms",
            "run": "1.936852ms"
          },
          "phaseCounts": {
            "fetch": 1,
            "primaryScan": 1
          },
          "phaseOperators": {
            "authorize": 1,
            "fetch": 1,
            "primaryScan": 1
          },
          "requestTime": "2021-04-30T18:40:13.239Z",
          "servicingHost": "127.0.0.1:8091",
          "executionTimings": {
            "#operator": "Authorize",
            "#stats": {
              "#phaseSwitches": 4,
              "execTime": "1.084µs",
              "servTime": "17.012µs"
            },
            "privileges": {
              "List": [
                {
                  "Target": "default:travel-sample.inventory.airline",
                  "Priv": 7,
                  "Props": 0
                }
              ]
            },
            "~child": {
              "#operator": "Sequence",
              "#stats": {
                "#phaseSwitches": 1,
                "execTime": "2.474µs"
              },
              "~children": [
                {
                  "#operator": "PrimaryScan3",
                  "#stats": {
                    "#itemsOut": 1,
                    "#phaseSwitches": 7,
                    "execTime": "18.584µs",
                    "kernTime": "8.869µs",
                    "servTime": "1.384334ms"
                  },
                  "bucket": "travel-sample",
                  "index": "def_inventory_airline_primary",
                  "index_projection": {
                    "primary_key": true
                  },
                  "keyspace": "airline",
                  "limit": "1",
                  "namespace": "default",
                  "scope": "inventory",
                  "using": "gsi"
                },
                {
                  "#operator": "Fetch",
                  "#stats": {
                    "#itemsIn": 1,
                    "#itemsOut": 1,
                    "#phaseSwitches": 10,
                    "execTime": "25.64µs",
                    "kernTime": "1.427752ms",
                    "servTime": "362.482µs"
                  },
                  "bucket": "travel-sample",
                  "keyspace": "airline",
                  "namespace": "default",
                  "scope": "inventory"
                },
                {
                  "#operator": "InitialProject",
                  "#stats": {
                    "#itemsIn": 1,
                    "#itemsOut": 1,
                    "#phaseSwitches": 9,
                    "execTime": "6.006µs",
                    "kernTime": "1.825917ms"
                  },
                  "result_terms": [
                    {
                      "expr": "self",
                      "star": true
                    }
                  ]
                },
                {
                  "#operator": "Limit",
                  "#stats": {
                    "#itemsIn": 1,
                    "#itemsOut": 1,
                    "#phaseSwitches": 4,
                    "execTime": "2.409µs",
                    "kernTime": "2.094µs"
                  },
                  "expr": "1"
                },
                {
                  "#operator": "Stream",
                  "#stats": {
                    "#itemsIn": 1,
                    "#itemsOut": 1,
                    "#phaseSwitches": 6,
                    "execTime": "46.964µs",
                    "kernTime": "1.844828ms"
                  }
                }
              ]
            },
            "~versions": [
              "7.0.0-N1QL",
              "7.0.0-4960-enterprise"
            ]
          }
        }
      }

      Attribute Meta in System Keyspaces

      The meta().plan virtual attribute captures the whole query plan, and monitoring stats of various phases and involved query operators. The meta().plan must be explicitly called in the SELECT query projection list.

      The meta().plan attribute is enabled only for individual requests that are running (active_requests) or completed (completed_requests) when the profile is set to timings (profile ="timings") for each individual request. If at the engine level, the profile is set to off and individual requests have been run with profile ="timings", then the system keyspaces will return the plan only for those requests.

      Since there may be a combination of profile settings for all of the requests reported by the system keyspaces, not all requests returned will have a meta().plan attachment.

      For the system:prepareds requests, the meta().plan is available at all times since the PREPARE statement is not dependant on the profile setting.

      This attribute is enabled for the following system keyspaces:

      For a detailed example, see Example 5.

      Monitor Query Clusters

      Couchbase Server allows you to monitor many aspects of an active cluster: cluster-aware operations, diagnostics, and more system keyspaces features that cover multiple nodes. Functionalities include:

      • Ability to access active / completed / prepared requests across all Query nodes from SQL++.

      • Ability to list nodes by type and with status from SQL++.

      • Ability to list system keyspaces from system:keyspaces.

      • Extra fields in system:active_requests and system:completed_requests.

      • Counters to keep track of specific requests, such as cancelled requests.

      • Killing request for CREATE INDEX.

      System Keyspaces

      • The system:keyspaces keyspace can be augmented to list system keyspaces with a static map. The small disadvantage of this is that it has to be maintained as new system keyspaces are added.

      • The system:active_requests and system:completed_requests keyspaces can report scan consistency.

      • The system:prepareds keyspace can list min and max execution and service times, as well as average times.

      cbq-engine-cbauth

      cbq-engine-cbauth is an internal user that the query service uses to allow Query Workbench clients to query across multiple query nodes.

      Since Query Workbench can connect to the same node only when cbq-engine is running, Query Workbench cannot do any query-clustered operations.

      To get around this block, once the Query Workbench clients connect to a query node, this internal user (cbq-engine-cbauth) will be used to do any further inter-node user verification.

      System Vitals

      The Vitals API provides data about the running state and health of the query engine, such as number of logical cores, active threads, queued threads, CPU utilization, memory usage, network utilization, garbage collection percentage, and so on. This information can be very useful to assess the current workload and performance characteristics of a query engine, and hence load-balance the requests being sent to various query engines.

      For field names and meanings, refer to Vitals.

      Get System Vitals

      curl -u Administrator:pword http://localhost:8093/admin/vitals
      {
        "uptime": "7h39m32.668577197s",
        "local.time": "2021-04-30 18:42:39.517208807 +0000 UTC m=+27573.945319668",
        "version": "7.0.0-N1QL",
        "total.threads": 191,
        "cores": 2,
        "gc.num": 669810600,
        "gc.pause.time": "57.586373ms",
        "gc.pause.percent": 0,
        "memory.usage": 247985184,
        "memory.total": 11132383704,
        "memory.system": 495554808,
        "cpu.user.percent": 0,
        "cpu.sys.percent": 0,
        "request.completed.count": 140,
        "request.active.count": 0,
        "request.per.sec.1min": 0.0018,
        "request.per.sec.5min": 0.0055,
        "request.per.sec.15min": 0.0033,
        "request_time.mean": "536.348163ms",
        "request_time.median": "54.065567ms",
        "request_time.80percentile": "981.869933ms",
        "request_time.95percentile": "2.543128455s",
        "request_time.99percentile": "4.627922799s",
        "request.prepared.percent": 0
      }

      Monitor and Manage Active Requests

      The system:active_requests catalog lists all currently executing active requests or queries.

      For field names and meanings, refer to Requests. The profile related attributes are described in the section Attribute profile in Query Response.

      Get Active Requests

      To view active requests with Admin REST API:

      curl -u Administrator:pword http://localhost:8093/admin/active_requests

      To view active requests with SQL++, including the query plan:

      SELECT *, meta().plan FROM system:active_requests;

      Terminate an Active Request

      The DELETE command can be used to terminate an active request, for instance, a non-responding or a long-running query.

      To terminate an active request uuid with the Admin REST API:

      curl -u Administrator:pword -X DELETE http://localhost:8093/admin/active_requests/uuid

      To terminate an active request uuid with SQL++:

      DELETE FROM system:active_requests WHERE requestId = "uuid";

      Examples

      Example 3. Get Active
      SELECT *, meta().plan FROM system:active_requests;
      [
        {
          "active_requests": {
            "clientContextID": "81984707-a9cd-4b78-9110-d130eb580d7f",
            "elapsedTime": "65.543946ms",
            "executionTime": "65.507111ms",
            "node": "127.0.0.1:8091",
            "phaseCounts": {
              "primaryScan": 1
            },
            "phaseOperators": {
              "authorize": 1,
              "fetch": 1,
              "primaryScan": 1
            },
            "phaseTimes": {
              "authorize": "2.361862ms",
              "fetch": "7.222µs",
              "instantiate": "13.233µs",
              "parse": "660.048µs",
              "plan": "52.877µs",
              "primaryScan": "41.125271ms"
            },
            "remoteAddr": "127.0.0.1:57065",
            "requestId": "27e73286-c6cc-4c26-8977-ef8d68e91c8f",
            "requestTime": "2019-05-06 09:08:42.431161361 -0700 PDT m=+6976.301141271",
            "scanConsistency": "unbounded",
            "state": "running",
            "statement": "SELECT *, meta().plan FROM system:active_requests;",
            "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:66.0) Gecko/20100101 Firefox/66.0 (Couchbase Query Workbench (6.5.0-2859-enterprise))",
            "users": "Administrator"
          },
          "plan": { (1)
            "#operator": "Sequence",
            "#stats": {
              "#phaseSwitches": 1,
              "execTime": "1.661µs"
            },
            "~children": [
              {
                "#operator": "Authorize",
                "#stats": {
                  "#phaseSwitches": 3,
                  "execTime": "4.844µs",
                  "servTime": "2.357018ms"
                },
                // ...
              }
            ]
          },
          "plan": {
            "#operator": "Sequence",
            "#stats": {
              "#phaseSwitches": 1,
              "execTime": "1.661µs"
            },
            "~children": [
              {
                "#operator": "Authorize",
                "#stats": {
                  "#phaseSwitches": 3,
                  "execTime": "4.844µs",
                  "servTime": "2.357018ms"
                },
                "privileges": {
                  "List": [
                    {
                      "Priv": 4,
                      "Target": "#system:active_requests"
                    }
                  ]
                },
                "~child": {
                  "#operator": "Sequence",
                  "#stats": {
                    "#phaseSwitches": 1,
                    "execTime": "2.71µs"
                  },
                  "~children": [
                    {
                      "#operator": "PrimaryScan",
                      "#stats": {
                        "#itemsOut": 1,
                        "#phaseSwitches": 7,
                        "execTime": "22.314µs",
                        "kernTime": "2.13µs",
                        "servTime": "41.102957ms"
                      },
                      "index": "#primary",
                      "keyspace": "active_requests",
                      "namespace": "#system",
                      "using": "system"
                    },
                    {
                      "#operator": "Fetch",
                      "#stats": {
                        "#itemsIn": 1,
                        "#phaseSwitches": 5,
                        "execTime": "7.222µs",
                        "kernTime": "41.130913ms",
                        "servTime": "22.888285ms",
                        "state": "services"
                      },
                      "keyspace": "active_requests",
                      "namespace": "#system"
                    },
                    {
                      "#operator": "Sequence",
                      "#stats": {
                        "#phaseSwitches": 1,
                        "execTime": "1.544µs"
                      },
                      "~children": [
                        {
                          "#operator": "InitialProject",
                          "#stats": {
                            "#phaseSwitches": 1,
                            "execTime": "980ns",
                            "kernTime": "64.066618ms",
                            "state": "kernel"
                          },
                          "result_terms": [
                            {
                              "expr": "self",
                              "star": true
                            },
                            {
                              "expr": "(meta(`active_requests`).`plan`)"
                            }
                          ]
                        },
                        {
                          "#operator": "FinalProject",
                          "#stats": {
                            "#phaseSwitches": 1,
                            "execTime": "827ns"
                          }
                        }
                      ]
                    }
                  ]
                }
              },
              {
                "#operator": "Stream",
                "#stats": {
                  "#phaseSwitches": 1,
                  "execTime": "1.29µs",
                  "kernTime": "66.511806ms",
                  "state": "kernel"
                }
              }
            ],
            "~versions": [
              "2.0.0-N1QL",
              "6.5.0-2859-enterprise"
            ]
          }
        }
      ]
      1 The plan section contains a tree of operators that combine to execute the SQL++ query. The root operator is a Sequence, which itself has a collection of child operators like Authorize, PrimaryScan, Fetch, and possibly even more Sequences.

      Monitor and Manage Prepared Statements

      The system:prepareds catalog provides data about the known prepared statements and their state in a query engine’s prepared statement cache. For each prepared statement, this catalog provides information such as name, statement, query plan, last use time, number of uses, and so on.

      For field names and meanings, refer to Statements. The system:prepareds catalog returns all the properties that the SQL++ Admin REST API would return for a specific prepared statement. In addition, the system:prepareds catalog also returns the following properties.

      Name Description Schema

      node
      required

      The node on which the prepared statement is stored.

      string

      namespace
      required

      The namespace in which the prepared statement is stored. Currently, only the default namespace is available.

      string

      A prepared statement is created and stored relative to the current query context. You can create multiple prepared statements with the same name, each stored relative to a different query context. This enables you to run multiple instances of the same application against different datasets.

      When there are multiple prepared statements with the same name in different query contexts, the name of the prepared statement in the system:prepareds catalog includes the associated query context in brackets.

      Get Prepared Statements

      To get a list of all known prepared statements, you can use the Admin REST API or a SQL++ query:

      curl -u Administrator:pword http://localhost:8093/admin/prepareds
      SELECT * FROM system:prepareds;

      To get information about a specific prepared statement example1, you can use the Admin REST API or a SQL++ query:

      curl -u Administrator:pword http://localhost:8093/admin/prepareds/example1
      SELECT * FROM system:prepareds WHERE name = "example1";

      Delete Prepared Statements

      To delete a specific prepared statement p1, you can use the Admin REST API or a SQL++ query:

      curl -u Administrator:pword -X DELETE http://localhost:8093/admin/prepareds/p1
      DELETE FROM system:prepareds WHERE name = "p1";

      To delete all the known prepared statements, you must use a SQL++ query:

      DELETE FROM system:prepareds;

      Examples

      Example 4. Get Prepared
      Prepared statement with default query context — using cbq
      \UNSET -query_context;
      PREPARE p1 AS SELECT * FROM `travel-sample`.inventory.airline WHERE iata = "U2";
      {
        "requestID": "64069886-eb17-4fa6-8cc8-e60ebe93d97c",
        "signature": "json",
        "results": [
          {
            "encoded_plan": "H4sIAAAAAAAA/wEAAP//AAAAAAAAAAA=",
            "featureControls": 76,
            "indexApiVersion": 4,
            "indexScanKeyspaces": {
              "default:travel-sample.inventory.airline": false
            },
            "name": "[127.0.0.1:8091]p1",
            "namespace": "default",
            "operator": {
              "#operator": "Authorize",
              "privileges": {
                "List": [
                  {
                    "Priv": 7,
                    "Props": 0,
                    "Target": "default:travel-sample.inventory.airline"
                  }
                ]
              },
              "~child": {
                "#operator": "Sequence",
                "~children": [
                  {
                    "#operator": "Sequence",
                    "~children": [
                      {
                        "#operator": "PrimaryScan3",
                        "bucket": "travel-sample",
                        "index": "def_inventory_airline_primary",
                        "index_projection": {
                          "primary_key": true
                        },
                        "keyspace": "airline",
                        "namespace": "default",
                        "scope": "inventory",
                        "using": "gsi"
                      },
                      {
                        "#operator": "Fetch",
                        "bucket": "travel-sample",
                        "keyspace": "airline",
                        "namespace": "default",
                        "scope": "inventory"
                      },
                      {
                        "#operator": "Parallel",
                        "~child": {
                          "#operator": "Sequence",
                          "~children": [
                            {
                              "#operator": "Filter",
                              "condition": "((`airline`.`iata`) = \"U2\")"
                            },
                            {
                              "#operator": "InitialProject",
                              "result_terms": [
                                {
                                  "expr": "self",
                                  "star": true
                                }
                              ]
                            }
                          ]
                        }
                      }
                    ]
                  },
                  {
                    "#operator": "Stream"
                  }
                ]
              }
            },
            "queryContext": "",
            "reqType": "SELECT",
            "signature": {
              "*": "*"
            },
            "text": "PREPARE p1 AS SELECT * FROM `travel-sample`.inventory.airline WHERE iata = \"U2\";",
            "useCBO": true
          }
        ],
        "status": "success",
        "metrics": {
          "elapsedTime": "105.814848ms",
          "executionTime": "105.648798ms",
          "resultCount": 1,
          "resultSize": 3301,
          "serviceLoad": 12
        }
      }
      Prepared statement with specified query context — using cbq
      \SET -query_context travel-sample.inventory;
      PREPARE p1 AS SELECT * FROM airline WHERE iata = "U2";
      {
        "requestID": "1c90603e-5e42-42b4-9362-4fc96bf895ac",
        "signature": "json",
        "results": [
          {
            "encoded_plan": "H4sIAAAAAAAA/wEAAP//AAAAAAAAAAA=",
            "featureControls": 76,
            "indexApiVersion": 4,
            "indexScanKeyspaces": {
              "default:travel-sample.inventory.airline": false
            },
            "name": "[127.0.0.1:8091]p1",
            "namespace": "default",
            "operator": {
              "#operator": "Authorize",
              "privileges": {
                "List": [
                  {
                    "Priv": 7,
                    "Props": 0,
                    "Target": "default:travel-sample.inventory.airline"
                  }
                ]
              },
              "~child": {
                "#operator": "Sequence",
                "~children": [
                  {
                    "#operator": "Sequence",
                    "~children": [
                      {
                        "#operator": "PrimaryScan3",
                        "bucket": "travel-sample",
                        "index": "def_inventory_airline_primary",
                        "index_projection": {
                          "primary_key": true
                        },
                        "keyspace": "airline",
                        "namespace": "default",
                        "scope": "inventory",
                        "using": "gsi"
                      },
                      {
                        "#operator": "Fetch",
                        "bucket": "travel-sample",
                        "keyspace": "airline",
                        "namespace": "default",
                        "scope": "inventory"
                      },
                      {
                        "#operator": "Parallel",
                        "~child": {
                          "#operator": "Sequence",
                          "~children": [
                            {
                              "#operator": "Filter",
                              "condition": "((`airline`.`iata`) = \"U2\")"
                            },
                            {
                              "#operator": "InitialProject",
                              "result_terms": [
                                {
                                  "expr": "self",
                                  "star": true
                                }
                              ]
                            }
                          ]
                        }
                      }
                    ]
                  },
                  {
                    "#operator": "Stream"
                  }
                ]
              }
            },
            "queryContext": "travel-sample.inventory",
            "reqType": "SELECT",
            "signature": {
              "*": "*"
            },
            "text": "PREPARE p1 AS SELECT * FROM airline WHERE iata = \"U2\";",
            "useCBO": true
          }
        ],
        "status": "success",
        "metrics": {
          "elapsedTime": "17.476424ms",
          "executionTime": "17.187836ms",
          "resultCount": 1,
          "resultSize": 3298,
          "serviceLoad": 12
        }
      }
      List prepared statements
      SELECT *, meta().plan FROM system:prepareds;
      {
        "requestID": "d976e59a-d74e-4350-b0df-fa137099d594",
        "signature": {
          "*": "*",
          "plan": "json"
        },
        "results": [
          {
            "plan": {
              // ...
            },
            "prepareds": {
              "encoded_plan": "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",
              "featuresControl": 76,
              "indexApiVersion": 4,
              "indexScanKeyspaces": {
                "default:travel-sample.inventory.airline": false
              },
              "name": "p1", (1)
              "namespace": "default",
              "node": "127.0.0.1:8091",
              "statement": "PREPARE p1 AS SELECT * FROM `travel-sample`.inventory.airline WHERE iata = \"U2\";",
              "uses": 0
            }
          },
          {
            "plan": {
              // ...
            },
            "prepareds": {
              "encoded_plan": "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",
              "featuresControl": 76,
              "indexApiVersion": 4,
              "indexScanKeyspaces": {
                "default:travel-sample.inventory.airline": false
              },
              "name": "p1(travel-sample.inventory)", (2)
              "namespace": "default",
              "node": "127.0.0.1:8091",
              "statement": "PREPARE p1 AS SELECT * FROM airline WHERE iata = \"U2\";",
              "uses": 0
            }
          }
        ],
        "status": "success",
        "metrics": {
          "elapsedTime": "25.323496ms",
          "executionTime": "25.173646ms",
          "resultCount": 2,
          "resultSize": 7891,
          "serviceLoad": 12
        }
      }

      Note that the names of the prepared statements are identical, but they are associated with different query contexts.

      1 The name of the prepared statement for the default query context
      2 The name of the prepared statement showing the associated query context

      Monitor and Manage Completed Requests

      By default, the system:completed_requests catalog maintains a list of the most recent completed requests that have run longer than a predefined threshold of time. (You can also log completed requests that meet other conditions that you define.)

      For each completed request, this catalog maintains information such as requestId, statement text, prepared name (if prepared statement), request time, service time, and so on. This information provides a general insight into the health and performance of the query engine and the cluster.

      For field names and meanings, refer to Requests. Most field names and meanings match exactly those of system:active_requests.

      Note that the completed state means that the request was started and completed by the Query service, but it does not mean that it was necessarily successful. The request could have been successful, or completed with errors.

      To find requests that completed successfully, search for completed requests whose state is completed and whose errorCount field has the value 0.

      Request profiling affects the system:completed_requests keyspace in the following ways:

      • When the feature is turned on, completed requests are stored with their execution plan.

      • Profiling information is likely to use 100KB+ per entry.

      • Due to the added overhead of running both profiling and logging, we recommend turning on both of them only when needed. Running only one of them continuously has no noticeable affect on performance.

      • Profiling does not carry any extra cost beyond memory for completed requests, so it’s fine to run it continuously.

      Get Completed Requests

      To get a list of all logged completed requests using the Admin REST API:

      curl -u Administrator:pword http://localhost:8093/admin/completed_requests

      To get a list of all logged completed requests using SQL++, including the query plan:

      SELECT *, meta().plan FROM system:completed_requests;

      To get a list of all logged completed requests using SQL++, including only successful requests:

      SELECT * FROM system:completed_requests
      WHERE state = "completed" AND errorCount = 0;

      Purge the Completed Requests

      To purge a completed request uuid with the Admin REST API:

      curl -u Administrator:pword -X DELETE http://localhost:8093/admin/completed_requests/uuid

      To purge a completed request uuid with SQL++:

      DELETE FROM system:completed_requests WHERE requestId = "uuid";

      To purge the completed requests for a given time period, use:

      DELETE FROM system:completed_requests WHERE requestTime LIKE "2015-09-09%";

      Configure the Completed Requests

      You can configure the system:completed_requests keyspace by specifying parameters through the Admin API settings endpoint.

      In Couchbase Server 6.5 and later, you can specify the conditions for completed request logging using the completed field.

      This field takes a JSON object containing the names and values of logging qualifiers. Completed requests that meet the defined qualifiers are logged.

      curl http://localhost:8093/admin/settings -u Administrator:password \
        -H 'Content-Type: application/json' \
        -d '{"completed": {"user": "marco", "error": 12003}}'

      Logging Qualifiers

      You can specify the following logging qualifiers. A completed request is logged if any of the qualifiers are met (logical OR).

      threshold

      The execution time threshold in milliseconds.

      aborted

      Whether to log requests that generate a panic.

      error

      Log requests returning this error number.

      client

      Log requests from this IP address.

      user

      Log requests with this user name.

      context

      Log requests with this client context ID.

      For full details, refer to Logging parameters.

      The basic syntax adds a qualifier to the logging parameters, i.e. any existing qualifiers are not removed. You can change the value of a logging qualifier by specifying the same qualifier again with a new value.

      To add a new instance of an existing qualifier, use a plus sign (+) before the qualifier name, e.g. +user. To remove a qualifier, use a minus sign (-) before the qualifier name, e.g. -user.

      For example, the following request will add user simon to those tracked, and remove error 12003.

      curl http://localhost:8093/admin/settings -u Administrator:password \
        -H 'Content-Type: application/json' \
        -d '{"completed": {"+user": "simon", "-error": 12003}}'

      Similarly, you could remove all logging by execution time with the following request, as long as the value matches the existing threshold.

      curl http://localhost:8093/admin/settings -u Administrator:password \
        -H 'Content-Type: application/json' \
        -d '{"completed": {"-threshold": 1000}}'

      Tagged Sets

      You can also specify qualifiers that have to be met as a group for the completed request to be logged (logical AND).

      To do this, specify the tag field along with a set of qualifiers, like so:

      curl http://localhost:8093/admin/settings -u Administrator:password \
        -H 'Content-Type: application/json' \
        -d '{"completed": {"user": "marco", "error": 12003, "tag": "both_user_and_error"}}'

      In this case, the request will be logged when both user and error match.

      The tag name can be any string that is meaningful and unique. Requests that match a tagged set of conditions are logged with a field ~tag, which is set to the name of the tag.

      To add a qualifier to a tagged set, specify the tag name again along with the new qualifier:

      curl http://localhost:8093/admin/settings -u Administrator:password \
        -H 'Content-Type: application/json' \
        -d '{"completed": {"client": "172.1.2.3", "tag": "both_user_and_error"}}'

      You cannot add a new instance of an existing qualifier to a tagged set using a plus sign (+) before the qualifier name. For example, you cannot add a user qualifier to a tagged set that already contains a user qualifier. If you need to track two users with the same error, create two tagged sets, one per user.

      You can remove a qualifier from a tagged set using a minus sign (-) before the qualifier name, e.g. -user. When you remove the last qualifier from a tagged set, the tagged set is removed.

      You can specify multiple tagged sets. In this case, completed requests are logged if they match all of the qualifiers in any of the tagged sets.

      You can also specify a mixture of tagged sets and individual qualifiers. In this case, completed requests are logged if they match any of the individual qualifiers, or all of the qualifiers in any of the tagged sets.

      Completed Threshold

      The completed-threshold field provides another way of specifying the threshold qualifier within the completed field.

      This field sets the minimum request duration after which requests are added to the system:completed_requests catalog. The default value is 1000ms. Specify 0 to log all requests and -1 to not log any requests to the keyspace.

      To specify a different value, use:

      curl http://localhost:port/admin/settings -u user:pword \
        -H 'Content-Type: application/json' \
        -d '{"completed-threshold":0}'

      Completed Limit

      The completed-limit field sets the number of most recent requests to be tracked in the system:completed_requests catalog. The default value is 4000. Specify 0 to not track any requests and -1 to set no limit.

      To specify a different value, use:

      curl http://localhost:port/admin/settings -u user:pword \
        -H 'Content-Type: application/json' \
        -d '{"completed-limit":1000}'

      Examples

      Example 5. Completed Request

      First, using the cbq shell, we set profile = "timings" and run a long query which takes at least 1000ms (the default value of the completed-threshold query setting) to get registered in the system:completed_requests keyspace:

      Query 1
      \set -profile "timings";
      SELECT * FROM `travel-sample`.inventory.route ORDER BY sourceairport;

      Now, using the cbq shell, we change the profile setting to "phases" and rerun another long query:

      Query 2
      \set -profile "phases";
      SELECT * FROM `travel-sample`.inventory.route ORDER BY destinationairport;

      Run a query system:completed_requests keyspace with meta().plan.

      Query 3
      SELECT meta().plan, * from system:completed_requests;
      Result
      {
        "requestID": "4a36e1dc-cea0-4ba2-a428-258511d50582",
        "signature": {
          "*": "*",
          "plan": "json"
        },
        "results": [
          // ...
          { (1)
            "completed_requests": {
              "elapsedTime": "15.641879295s",
              "errorCount": 0,
              "node": "127.0.0.1:8091",
              "phaseCounts": {
                "fetch": 24024,
                "primaryScan": 24024,
                "sort": 24024
              },
              "phaseOperators": {
                "authorize": 1,
                "fetch": 1,
                "primaryScan": 1,
                "sort": 1
              },
              "phaseTimes": {
                "authorize": "51.305µs",
                "fetch": "3.27276723s",
                "instantiate": "60.662µs",
                "parse": "66.701943ms",
                "plan": "15.12951ms",
                "primaryScan": "171.439769ms",
                "run": "15.548781894s",
                "sort": "153.767638ms"
              },
              "remoteAddr": "172.17.0.1:56962",
              "requestId": "08445bae-66ef-4ccd-8b2d-ea899b453a1b",
              "requestTime": "2021-04-30T21:14:57.576Z",
              "resultCount": 24024,
              "resultSize": 81821919,
              "scanConsistency": "unbounded",
              "serviceTime": "15.630714144s",
              "state": "completed",
              "statement": "SELECT * FROM `travel-sample`.inventory.route ORDER BY destinationairport;",
              "useCBO": true,
              "userAgent": "Go-http-client/1.1 (CBQ/2.0)",
              "users": "Administrator"
            }
          },
          // ...
          { (2)
            "completed_requests": {
              "elapsedTime": "15.321128463s",
              "errorCount": 0,
              "node": "127.0.0.1:8091",
              "phaseCounts": {
                "fetch": 24024,
                "primaryScan": 24024,
                "sort": 24024
              },
              "phaseOperators": {
                "authorize": 1,
                "fetch": 1,
                "primaryScan": 1,
                "sort": 1
              },
              "phaseTimes": {
                "authorize": "23.037µs",
                "fetch": "3.092306635s",
                "instantiate": "7.313569ms",
                "parse": "579.368µs",
                "plan": "2.449143ms",
                "primaryScan": "153.686873ms",
                "run": "15.29433203s",
                "sort": "147.889352ms"
              },
              "remoteAddr": "172.17.0.1:56900",
              "requestId": "5eefc9e5-bdaa-4824-bcd7-47977eb1f08a",
              "requestTime": "2021-04-30T21:13:58.707Z",
              "resultCount": 24024,
              "resultSize": 81821919,
              "scanConsistency": "unbounded",
              "serviceTime": "15.30510306s",
              "state": "completed",
              "statement": "SELECT * FROM `travel-sample`.inventory.route ORDER BY sourceairport;",
              "useCBO": true,
              "userAgent": "Go-http-client/1.1 (CBQ/2.0)",
              "users": "Administrator"
            },
            "plan": {
              "#operator": "Authorize",
              "#stats": {
                "#phaseSwitches": 4,
                "execTime": "1.725µs",
                "servTime": "21.312µs"
              },
              "privileges": {
                "List": [
                  {
                    "Priv": 7,
                    "Props": 0,
                    "Target": "default:travel-sample.inventory.route"
                  }
                ]
              },
              "~child": {
                "#operator": "Sequence",
                "#stats": {
                  "#phaseSwitches": 2,
                  "execTime": "1.499µs"
                },
                "~children": [
                  {
                    "#operator": "PrimaryScan3",
                    "#stats": {
                      "#heartbeatYields": 6,
                      "#itemsOut": 24024,
                      "#phaseSwitches": 96099,
                      "execTime": "84.366121ms",
                      "kernTime": "3.021901421s",
                      "servTime": "69.320752ms"
                    },
                    "bucket": "travel-sample",
                    "index": "def_inventory_route_primary",
                    "index_projection": {
                      "primary_key": true
                    },
                    "keyspace": "route",
                    "namespace": "default",
                    "scope": "inventory",
                    "using": "gsi"
                  },
                  {
                    "#operator": "Fetch",
                    "#stats": {
                      "#heartbeatYields": 7258,
                      "#itemsIn": 24024,
                      "#itemsOut": 24024,
                      "#phaseSwitches": 99104,
                      "execTime": "70.34694ms",
                      "kernTime": "142.630196ms",
                      "servTime": "3.021959695s"
                    },
                    "bucket": "travel-sample",
                    "keyspace": "route",
                    "namespace": "default",
                    "scope": "inventory"
                  },
                  {
                    "#operator": "InitialProject",
                    "#stats": {
                      "#itemsIn": 24024,
                      "#itemsOut": 24024,
                      "#phaseSwitches": 96100,
                      "execTime": "15.331951ms",
                      "kernTime": "3.219612458s"
                    },
                    "result_terms": [
                      {
                        "expr": "self",
                        "star": true
                      }
                    ]
                  },
                  {
                    "#operator": "Order",
                    "#stats": {
                      "#itemsIn": 24024,
                      "#itemsOut": 24024,
                      "#phaseSwitches": 72078,
                      "execTime": "147.889352ms",
                      "kernTime": "3.229055752s"
                    },
                    "sort_terms": [
                      {
                        "expr": "(`route`.`sourceairport`)"
                      }
                    ]
                  },
                  {
                    "#operator": "Stream",
                    "#stats": {
                      "#itemsIn": 24024,
                      "#itemsOut": 24024,
                      "#phaseSwitches": 24025,
                      "execTime": "11.851634134s"
                    }
                  }
                ]
              },
              "~versions": [
                "7.0.0-N1QL",
                "7.0.0-4960-enterprise"
              ]
            }
          }
        ],
        "status": "success",
        "metrics": {
          "elapsedTime": "172.831251ms",
          "executionTime": "172.586836ms",
          "resultCount": 40,
          "resultSize": 65181,
          "serviceLoad": 12
        },
        "profile": { (3)
          "phaseTimes": {
            "authorize": "19.912µs",
            "fetch": "123.022426ms",
            "instantiate": "29.424µs",
            "parse": "6.414711ms",
            "plan": "3.19076ms",
            "primaryScan": "55.521683ms",
            "run": "158.514001ms"
          },
          "phaseCounts": {
            "fetch": 40,
            "primaryScan": 40
          },
          "phaseOperators": {
            "authorize": 1,
            "fetch": 1,
            "primaryScan": 1
          },
          "requestTime": "2021-04-30T21:15:18.104Z",
          "servicingHost": "127.0.0.1:8091"
        }
      }

      This example shows:

      1 The profile attribute with all phases-related statistics for Query 2.
      2 The meta().plan with all detailed statistics collected for Query 1.
      3 The profile attribute with all phases-related statistics for this query itself, which is querying the system:completed_requests keyspace.

      Monitor Your User Info

      The system:my_user_info catalog maintains a list of all information of your profile.

      To see your current information, use:

      SELECT * FROM system:my_user_info;

      This will result in a list similar to:

      [
        {
          "my_user_info": {
            "domain": "local",
            "external_groups": [],
            "groups": [],
            "id": "jane",
            "name": "Jane Doe",
            "password_change_date": "2019-05-07T02:31:53.000Z",
            "roles": [
              {
                "origins": [
                  {
                    "type": "user"
                  }
                ],
                "role": "admin"
              }
            ]
          }
        }
      ]

      Monitor All User Info

      The system:user_info catalog maintains a list of all current users in your bucket and their information.

      To see the list of all current users, use:

      SELECT * FROM system:user_info;

      This will result in a list similar to:

      [
        {
          "user_info": {
            "domain": "local",
            "external_groups": [],
            "groups": [],
            "id": "jane",
            "name": "Jane Doe",
            "password_change_date": "2019-05-07T02:31:53.000Z",
            "roles": [
              {
                "origins": [
                  {
                    "type": "user"
                  }
                ],
                "role": "admin"
              }
            ]
          }
        },
        {
          "user_info": {
            "domain": "ns_server",
            "id": "Administrator",
            "name": "Administrator",
            "roles": [
              {
                "role": "admin"
              }
            ]
          }
        }
      ]

      Monitor Nodes

      The system:nodes catalog shows the datastore topology information. This is separate from the Query clustering view, in that Query clustering shows a map of the Query cluster, as provided by the cluster manager, while system:nodes shows a view of the nodes and services that make up the actual datastore, which may or may not include Query nodes.

      • The dichotomy is important in that Query nodes could be clustered by one entity (e.g. Zookeeper) and be connected to a clustered datastore (e.g. Couchbase) such that each does not have visibility of the other.

      • Should SQL++ be extended to be able to concurrently connect to multiple datastores, each datastore will report its own topology, so that system:nodes offers a complete view of all the storage nodes, whatever those may be.

      • The system:nodes keyspace provides a way to report services advertised by each node as well as services that are actually running. This is datastore dependent.

      • Query clustering is still reported by the /admin endpoints.

      To see the list of all current node information, use:

      SELECT * FROM system:nodes;

      This will result in a list similar to:

      [
        {
          "nodes": {
            "name": "127.0.0.1:8091",
            "ports": {
              "cbas": 8095,
              "cbasAdmin": 9110,
              "cbasCc": 9111,
              "cbasSSL": 18095,
              "eventingAdminPort": 8096,
              "eventingSSL": 18096,
              "fts": 8094,
              "ftsSSL": 18094,
              "indexAdmin": 9100,
              "indexHttp": 9102,
              "indexHttps": 19102,
              "indexScan": 9101,
              "indexStreamCatchup": 9104,
              "indexStreamInit": 9103,
              "indexStreamMaint": 9105,
              "kv": 11210,
              "kvSSL": 11207,
              "n1ql": 8093,
              "n1qlSSL": 18093
            },
            "services": [
              "cbas",
              "eventing",
              "fts",
              "index",
              "kv",
              "n1ql"
            ]
          }
        }
      ]

      Monitor Applicable Roles

      The system:applicable_roles catalog maintains a list of all applicable roles and grantee of each bucket.

      To see the list of all current applicable role information, use:

      SELECT * FROM system:applicable_roles;

      This will result in a list similar to:

      [
        {
          "applicable_roles": {
            "grantee": "anil",
            "role": "replication_admin"
          }
        },
        {
          "applicable_roles": {
            "bucket_name": "travel-sample",
            "grantee": "anil",
            "role": "select"
          }
        },
        {
          "applicable_roles": {
            "bucket_name": "*",
            "grantee": "anil",
            "role": "select"
          }
        }
      ]

      For more examples, take a look at the blog: Optimize SQL++ performance using request profiling.

      Monitor Statistics

      The system:dictionary catalog maintains a list of the on-disk optimizer statistics stored in the _query collection within the _system scope.

      If you have multiple query nodes, the data retrieved from this catalog will be the same, regardless of the node on which you run the query.

      To see the list of on-disk optimizer statistics, use:

      SELECT * FROM system:dictionary;

      This will result in a list similar to:

      [
        {
          "dictionary": {
            "avgDocKeySize": 12,
            "avgDocSize": 278,
            "bucket": "travel-sample",
            "distributionKeys": [
              "airportname",
              "faa",
              "city"
            ],
            "docCount": 1968,
            "indexes": [
              {
                "indexId": "bc3048e87bf84828",
                "indexName": "def_inventory_airport_primary",
                "indexStats": [
                  {
                    "avgItemSize": 24,
                    "avgPageSize": 11760,
                    "numItems": 1968,
                    "numPages": 4,
                    "resRatio": 1
                  }
                ]
              },
              // ...
            ],
            "keyspace": "airport",
            "namespace": "default",
            "scope": "inventory"
          }
        },
        // ...
      ]

      This catalog contains an array of dictionaries, one for each keyspace for which optimizer statistics are available. Each dictionary gives the following information:

      Name Description Schema

      avgDocKeySize
      required

      Average doc key size.

      Integer

      avgDocSize
      required

      Average doc size.

      Integer

      bucket
      required

      The bucket for which statistics are available.

      String

      keyspace
      required

      The keyspace for which statistics are available.

      String

      namespace
      required

      The namespace for which statistics are available.

      String

      scope
      required

      The scope for which statistics are available.

      String

      distributionKeys
      required

      Distribution keys for which histograms are available.

      String array

      docCount
      required

      Document count.

      Integer

      indexes
      required

      An array of indexes in this keyspace for which statistics are available.

      Indexes array

      node
      required

      The query node where this dictionary cache is resident.

      String

      Indexes

      Name Description Schema

      indexId
      required

      The index ID.

      String

      indexName
      required

      The index name.

      String

      indexStats
      required

      An array of statistics for each index, with one element for each index partition.

      Index Statistics

      Name Description Schema

      avgItemSize
      required

      Average item size.

      Integer

      avgPageSize
      required

      Average page size.

      Integer

      numItems
      required

      Number of items.

      Integer

      numPages
      required

      Number of pages.

      Integer

      resRatio
      required

      Resident ratio.

      Integer

      For further details, refer to UPDATE STATISTICS.

      Monitor Cached Statistics

      The system:dictionary_cache catalog maintains a list of the in-memory cached subset of the optimizer statistics.

      If you have multiple query nodes, the data retrieved from this node shows cached optimizer statistics from all nodes. Individual nodes may have a different subset of cached information.

      To see the list of in-memory optimizer statistics, use:

      SELECT * FROM system:dictionary_cache;

      This will result in a list similar to:

      [
        {
          "dictionary_cache": {
            "avgDocKeySize": 12,
            "avgDocSize": 278,
            "bucket": "travel-sample",
            "distributionKeys": [
              "airportname",
              "faa",
              "city"
            ],
            "docCount": 1968,
            "indexes": [
              {
                "indexId": "bc3048e87bf84828",
                "indexName": "def_inventory_airport_primary",
                "indexStats": [
                  {
                    "avgItemSize": 24,
                    "avgPageSize": 11760,
                    "numItems": 1968,
                    "numPages": 4,
                    "resRatio": 1
                  }
                ]
              },
              // ...
            ],
            "keyspace": "airport",
            "namespace": "default",
            "node": "172.23.0.3:8091",
            "scope": "inventory"
          }
        },
        // ...
      ]

      This catalog contains an array of dictionary caches, one for each keyspace for which optimizer statistics are available. Each dictionary cache gives the same information as the system:dictionary catalog.

      For further details, refer to UPDATE STATISTICS.

      Monitor Functions

      The system:functions catalog maintains a list of all user-defined functions across all nodes. To see the list of all user-defined functions, use:

      SELECT * FROM system:functions;

      This will result in a list similar to:

      [
        {
          "functions": {
            "definition": {
              "#language": "inline",
              "expression": "(((`fahrenheit` - 32) * 5) / 9)",
              "parameters": [
                "fahrenheit"
              ],
              "text": "((fahrenheit - 32) * 5/9)"
            },
            "identity": {
              "bucket": "travel-sample",
              "name": "celsius",
              "namespace": "default",
              "scope": "inventory",
              "type": "scope"
            }
          }
        },
        {
          "functions": {
            "definition": {
              "#language": "javascript",
              "library": "geohash-js",
              "name": "geohash-js",
              "object": "calculateAdjacent",
              "parameters": [
                "src",
                "dir"
              ]
            },
            "identity": {
              "name": "adjacent",
              "namespace": "default",
              "type": "global"
            }
          }
        },
        // ...
      ]

      This catalog contains the following attributes:

      Name Description Schema

      definition
      required

      The definition of the function.

      Definition object

      identity
      required

      The identity of the function.

      Identity object

      Definition

      Name Description Schema

      #language
      required

      The language of the function.

      Example: inline

      String

      parameters
      required

      The parameters required by the function.

      String array

      expression
      optional

      For inline functions only: the expression defining the function.

      String

      text
      optional

      For inline functions: the verbatim text of the function.


      For SQL++ managed user-defined functions: the external code defining the function.

      String

      library
      optional

      For external functions only: the library containing the function.

      String

      name
      optional

      For external functions only: the relative name of the library.

      String

      object
      optional

      For external functions only: the object defining the function.

      String

      Identity

      Name Description Schema

      name
      required

      The name of the function.

      String

      namespace
      required

      The namespace of the function.

      Example: default

      String

      type
      required

      The type of the function.

      Example: global

      String

      bucket
      optional

      For scoped functions only: the bucket containing the function.

      String

      scope
      optional

      For scoped functions only: the scope containing the function.

      String

      Monitor Cached Functions

      The system:functions_cache catalog maintains a list of recently-used user-defined functions across all nodes. The catalog also lists user-defined functions that have been called recently, but do not exist. To see the list of recently-used user-defined functions, use:

      SELECT * FROM system:functions_cache;

      This will result in a list similar to:

      [
        {
          "functions_cache": {
            "#language": "inline",
            "avgServiceTime": "3.066847ms",
            "expression": "(((`fahrenheit` - 32) * 5) / 9)",
            "lastUse": "2022-03-09 00:17:59.60659793 +0000 UTC m=+35951.429537902",
            "maxServiceTime": "3.066847ms",
            "minServiceTime": "0s",
            "name": "celsius",
            "namespace": "default",
            "node": "127.0.0.1:8091",
            "parameters": [
              "fahrenheit"
            ],
            "scope": "inventory",
            "text": "((fahrenheit - 32) * 5/9)",
            "type": "scope",
            "uses": 1
          }
        },
        {
          "functions_cache": {
            "#language": "javascript",
            "avgServiceTime": "56.892636ms",
            "lastUse": "2022-03-09 00:15:46.289934029 +0000 UTC m=+35818.007560703",
            "library": "geohash-js",
            "maxServiceTime": "146.025426ms",
            "minServiceTime": "0s",
            "name": "geohash-js",
            "namespace": "default",
            "node": "127.0.0.1:8091",
            "object": "calculateAdjacent",
            "parameters": [
              "src",
              "dir"
            ],
            "type": "global",
            "uses": 4
          }
        },
        {
          "functions_cache": {
            "avgServiceTime": "3.057421ms",
            "lastUse": "2022-03-09 00:17:25.396840275 +0000 UTC m=+35917.199008929",
            "maxServiceTime": "3.057421ms",
            "minServiceTime": "0s",
            "name": "notFound",
            "namespace": "default",
            "node": "127.0.0.1:8091",
            "type": "global",
            "undefined_function": true,
            "uses": 1
          }
        }
      ]

      This catalog contains the following attributes:

      Name Description Schema

      #language
      required

      The language of the function.

      Example: inline

      String

      name
      required

      The name of the function.

      String

      namespace
      required

      The namespace of the function.

      Example: default

      String

      parameters
      required

      The parameters required by the function.

      String array

      type
      required

      The type of the function.

      Example: global

      String

      scope
      optional

      For scoped functions only: the scope containing the function.

      String

      expression
      optional

      For inline functions only: the expression defining the function.

      String

      text
      optional

      For inline functions: the verbatim text of the function.


      For SQL++ managed user-defined functions: the external code defining the function.

      String

      library
      optional

      For external functions only: the library containing the function.

      String

      object
      optional

      For external functions only: the object defining the function.

      String

      avgServiceTime
      required

      The mean service time for the function.

      String

      lastUse
      required

      The date and time when the function was last used.

      String

      maxServiceTime
      required

      The maximum service time for the function.

      String

      minServiceTime
      required

      The minimum service time for the function.

      String

      node
      required

      The query node where the function is cached.

      String

      undefined_function
      required

      Whether the function exists or is undefined.

      Boolean

      uses
      required

      The number of uses of the function.

      Number

      Each query node keeps its own cache of recently-used user-defined functions, so you may see the same function listed for multiple nodes.

      Monitor Cached Tasks

      The system:tasks_cache catalog maintains a list of recently-used scheduled tasks, such as index advisor sessions. To see the list of recently-used scheduled tasks, use:

      SELECT * FROM system:tasks_cache;

      This will result in a list similar to:

      [
        {
          "tasks_cache": {
            "class": "advisor",
            "delay": "1h0m0s",
            "id": "bcd9f8e4-b324-504c-a98b-ace90dba869f",
            "name": "aa7f688a-bf29-438f-888f-eeaead87ca40",
            "node": "10.143.192.101:8091",
            "state": "scheduled",
            "subClass": "analyze",
            "submitTime": "2019-09-17 05:18:12.903122381 -0700 PDT m=+8460.550715992"
          }
        },
        {
          "tasks_cache": {
            "class": "advisor",
            "delay": "5m0s",
            "id": "254abec5-5782-543e-9ee0-d07da146b94e",
            "name": "ca2cfe56-01fa-4563-8eb0-a753af76d865",
            "node": "10.143.192.101:8091",
            "results": [
              // ...
            ],
            "startTime": "2019-09-17 05:03:31.821597725 -0700 PDT m=+7579.469191487",
            "state": "completed",
            "stopTime": "2019-09-17 05:03:31.963133954 -0700 PDT m=+7579.610727539",
            "subClass": "analyze",
            "submitTime": "2019-09-17 04:58:31.821230131 -0700 PDT m=+7279.468823737"
          }
        }
      ]

      This catalog contains the following attributes:

      Name Description Schema

      class
      required

      The class of the task.

      Example: advisor

      string

      delay
      required

      The scheduled duration of the task.

      string

      id
      required

      The internal ID of the task.

      string

      name
      required

      The name of the task.

      string

      node
      required

      The node where the task was started.

      string

      state
      required

      The state of the task.

      Values: scheduled, cancelled, completed

      string

      subClass
      required

      The subclass of the task.

      Example: analyze

      string

      submitTime
      required

      The date and time when the task was submitted.

      string

      results
      optional

      Not scheduled tasks: the results of the task.

      Any array

      startTime
      optional

      Not scheduled tasks: the date and time when the task started.

      string (date-time)

      stopTime
      optional

      Not scheduled tasks: the date and time when the task stopped.

      string (date-time)

      Refer to ADVISOR Function for more information on index advisor sessions.

      Monitor Transactions

      The system:transactions catalog maintains a list of active Couchbase transactions. To see the list of active transactions, use:

      SELECT * FROM system:transactions;

      This will result in a list similar to:

      [
        {
          "transactions": {
            "durabilityLevel": "majority",
            "durabilityTimeout": "2.5s",
            "expiryTime": "2021-04-21T12:53:48.598+01:00",
            "id": "85aea637-2288-434b-b7c5-413ad8e7c175",
            "isolationLevel": "READ COMMITED",
            "lastUse": "2021-04-21T12:51:48.598+01:00",
            "node": "127.0.0.1:8091",
            "numAtrs": 1024,
            "scanConsistency": "unbounded",
            "status": 0,
            "timeout": "2m0s",
            "usedMemory": 960,
            "uses": 1
          }
        // ...
        }
      ]

      This catalog contains the following attributes:

      Name Description Schema

      durabilityLevel
      required

      Durability level for all mutations within a transaction.

      string

      durabilityTimeout
      required

      Durability timeout per mutation within the transaction.

      string (duration)

      expiryTime
      required

      string (date-time)

      id
      required

      The transaction ID.

      string

      isolationLevel
      required

      The isolation level of the transaction.

      string

      lastUse
      required

      string (date-time)

      node
      required

      The node where the transaction was started.

      string

      numAtrs
      required

      The total number of active transaction records.

      integer

      scanConsistency
      required

      The transactional scan consistency.

      string

      status
      required

      integer

      timeout
      required

      The transaction timeout duration.

      string (duration)

      usedMemory
      required

      integer

      uses
      required

      integer

      Refer to SQL++ Support for Couchbase Transactions for more information.