- StarRocks
- Introduction to StarRocks
- Quick Start
- Deployment
- Deployment overview
- Prepare
- Deploy
- Deploy shared-nothing StarRocks
- Deploy and use shared-data StarRocks
- Manage
- Table Design
- Understand StarRocks table design
- Table types
- Data distribution
- Data compression
- Sort keys and prefix indexes
- Data Loading
- Concepts
- Overview of data loading
- Load data from a local file system or a streaming data source using HTTP PUT
- Load data from HDFS
- Load data from cloud storage
- Load data from Apache Kafka®
- Continuously load data from Apache Kafka®
- Load data from Apache Sparkâ„¢
- Load data using INSERT
- Load data using Stream Load transaction interface
- Realtime synchronization from MySQL
- Continuously load data from Apache Flink®
- Change data through loading
- Transform data at loading
- Data Unloading
- Query Data Lakes
- Query Acceleration
- Gather CBO statistics
- Synchronous materialized views
- Asynchronous materialized views
- Colocate Join
- Lateral Join
- Query Cache
- Index
- Computing the Number of Distinct Values
- Sorted streaming aggregate
- Integrations
- Administration
- Management
- Data recovery
- User Privilege and Authentication
- Performance Tuning
- Reference
- SQL Reference
- User Account Management
- Cluster Management
- ADD SQLBLACKLIST
- ADMIN CANCEL REPAIR TABLE
- ADMIN CHECK TABLET
- ADMIN REPAIR TABLE
- ADMIN SET CONFIG
- ADMIN SET REPLICA STATUS
- ADMIN SHOW CONFIG
- ADMIN SHOW REPLICA DISTRIBUTION
- ADMIN SHOW REPLICA STATUS
- ALTER RESOURCE GROUP
- ALTER STORAGE VOLUME
- ALTER SYSTEM
- CANCEL DECOMMISSION
- CREATE FILE
- CREATE RESOURCE GROUP
- CREATE STORAGE VOLUME
- DELETE SQLBLACKLIST
- DESC STORAGE VOLUME
- DROP FILE
- DROP RESOURCE GROUP
- DROP STORAGE VOLUME
- EXPLAIN
- INSTALL PLUGIN
- KILL
- SET
- SET DEFAULT STORAGE VOLUME
- SHOW BACKENDS
- SHOW BROKER
- SHOW COMPUTE NODES
- SHOW FILE
- SHOW FRONTENDS
- SHOW FULL COLUMNS
- SHOW INDEX
- SHOW PLUGINS
- SHOW PROC
- SHOW PROCESSLIST
- SHOW RESOURCE GROUP
- SHOW SQLBLACKLIST
- SHOW STORAGE VOLUMES
- SHOW TABLE STATUS
- SHOW VARIABLES
- UNINSTALL PLUGIN
- DDL
- ALTER DATABASE
- ALTER MATERIALIZED VIEW
- ALTER TABLE
- ALTER VIEW
- ALTER RESOURCE
- ANALYZE TABLE
- BACKUP
- CANCEL ALTER TABLE
- CANCEL BACKUP
- CANCEL RESTORE
- CREATE ANALYZE
- CREATE DATABASE
- CREATE EXTERNAL CATALOG
- CREATE FUNCTION
- CREATE INDEX
- CREATE MATERIALIZED VIEW
- CREATE REPOSITORY
- CREATE RESOURCE
- CREATE TABLE
- CREATE TABLE AS SELECT
- CREATE TABLE LIKE
- CREATE VIEW
- DROP ANALYZE
- DROP CATALOG
- DROP DATABASE
- DROP FUNCTION
- DROP INDEX
- DROP MATERIALIZED VIEW
- DROP REPOSITORY
- DROP RESOURCE
- DROP STATS
- DROP TABLE
- DROP VIEW
- HLL
- KILL ANALYZE
- RECOVER
- REFRESH EXTERNAL TABLE
- RESTORE
- SET CATALOG
- SHOW ANALYZE JOB
- SHOW ANALYZE STATUS
- SHOW FUNCTION
- SHOW META
- SHOW RESOURCES
- TRUNCATE TABLE
- USE
- DML
- ALTER LOAD
- ALTER ROUTINE LOAD
- BROKER LOAD
- CANCEL LOAD
- CANCEL EXPORT
- CANCEL REFRESH MATERIALIZED VIEW
- CREATE ROUTINE LOAD
- DELETE
- DROP TASK
- EXPORT
- GROUP BY
- INSERT
- PAUSE ROUTINE LOAD
- REFRESH MATERIALIZED VIEW
- RESUME ROUTINE LOAD
- SELECT
- SHOW ALTER TABLE
- SHOW ALTER MATERIALIZED VIEW
- SHOW BACKUP
- SHOW CATALOGS
- SHOW CREATE CATALOG
- SHOW CREATE DATABASE
- SHOW CREATE MATERIALIZED VIEW
- SHOW CREATE TABLE
- SHOW CREATE VIEW
- SHOW DATA
- SHOW DATABASES
- SHOW DELETE
- SHOW DYNAMIC PARTITION TABLES
- SHOW EXPORT
- SHOW LOAD
- SHOW MATERIALIZED VIEWS
- SHOW PARTITIONS
- SHOW PROPERTY
- SHOW REPOSITORIES
- SHOW RESTORE
- SHOW ROUTINE LOAD
- SHOW ROUTINE LOAD TASK
- SHOW SNAPSHOT
- SHOW TABLES
- SHOW TABLET
- SHOW TRANSACTION
- SPARK LOAD
- STOP ROUTINE LOAD
- STREAM LOAD
- SUBMIT TASK
- UPDATE
- Auxiliary Commands
- Data Types
- Keywords
- Function Reference
- Function list
- Java UDFs
- Window functions
- Lambda expression
- Aggregate Functions
- any_value
- approx_count_distinct
- array_agg
- avg
- bitmap
- bitmap_agg
- count
- corr
- covar_pop
- covar_samp
- group_concat
- grouping
- grouping_id
- hll_empty
- hll_hash
- hll_raw_agg
- hll_union
- hll_union_agg
- max
- max_by
- min
- min_by
- multi_distinct_sum
- multi_distinct_count
- percentile_approx
- percentile_cont
- percentile_disc
- retention
- stddev
- stddev_samp
- sum
- variance, variance_pop, var_pop
- var_samp
- window_funnel
- Array Functions
- all_match
- any_match
- array_agg
- array_append
- array_avg
- array_concat
- array_contains
- array_contains_all
- array_cum_sum
- array_difference
- array_distinct
- array_filter
- array_generate
- array_intersect
- array_join
- array_length
- array_map
- array_max
- array_min
- array_position
- array_remove
- array_slice
- array_sort
- array_sortby
- array_sum
- arrays_overlap
- array_to_bitmap
- cardinality
- element_at
- reverse
- unnest
- Bit Functions
- Bitmap Functions
- base64_to_bitmap
- bitmap_agg
- bitmap_and
- bitmap_andnot
- bitmap_contains
- bitmap_count
- bitmap_from_string
- bitmap_empty
- bitmap_has_any
- bitmap_hash
- bitmap_intersect
- bitmap_max
- bitmap_min
- bitmap_or
- bitmap_remove
- bitmap_subset_in_range
- bitmap_subset_limit
- bitmap_to_array
- bitmap_to_base64
- bitmap_to_string
- bitmap_union
- bitmap_union_count
- bitmap_union_int
- bitmap_xor
- intersect_count
- sub_bitmap
- to_bitmap
- JSON Functions
- Overview of JSON functions and operators
- JSON operators
- JSON constructor functions
- JSON query and processing functions
- Map Functions
- Binary Functions
- Conditional Functions
- Cryptographic Functions
- Date Functions
- add_months
- adddate
- convert_tz
- current_date
- current_time
- current_timestamp
- date
- date_add
- date_diff
- date_format
- date_slice
- date_sub, subdate
- date_trunc
- datediff
- day
- dayname
- dayofmonth
- dayofweek
- dayofyear
- days_add
- days_diff
- days_sub
- from_days
- from_unixtime
- hour
- hours_add
- hours_diff
- hours_sub
- last_day
- makedate
- microseconds_add
- microseconds_sub
- minute
- minutes_add
- minutes_diff
- minutes_sub
- month
- monthname
- months_add
- months_diff
- months_sub
- next_day
- now
- previous_day
- quarter
- second
- seconds_add
- seconds_diff
- seconds_sub
- str_to_date
- str2date
- time_slice
- time_to_sec
- timediff
- timestamp
- timestampadd
- timestampdiff
- to_date
- to_days
- unix_timestamp
- utc_timestamp
- week
- week_iso
- weekofyear
- weeks_add
- day_of_week_iso
- weeks_diff
- weeks_sub
- year
- years_add
- years_diff
- years_sub
- Geographic Functions
- Math Functions
- String Functions
- append_trailing_char_if_absent
- ascii
- char
- char_length
- character_length
- concat
- concat_ws
- ends_with
- find_in_set
- group_concat
- hex
- hex_decode_binary
- hex_decode_string
- instr
- lcase
- left
- length
- locate
- lower
- lpad
- ltrim
- money_format
- null_or_empty
- parse_url
- repeat
- replace
- reverse
- right
- rpad
- rtrim
- space
- split
- split_part
- starts_with
- strleft
- strright
- str_to_map
- substring
- trim
- ucase
- unhex
- upper
- url_decode
- url_encode
- Pattern Matching Functions
- Percentile Functions
- Scalar Functions
- Struct Functions
- Table Functions
- Utility Functions
- cast function
- hash function
- AUTO_INCREMENT
- Generated columns
- System variables
- User-defined variables
- Error code
- System limits
- AWS IAM policies
- SQL Reference
- FAQ
- Benchmark
- Ecosystem Release Notes
- Developers
- Contribute to StarRocks
- Code Style Guides
- Use the debuginfo file for debugging
- Development Environment
- Trace Tools
Query queues
This topic describes how to manage query queues in StarRocks.
From v2.5, StarRocks supports query queues. With query queues enabled, StarRocks automatically queues the incoming queries when the concurrency threshold or resource limit is reached, thereby avoiding the overload deteriorating. Pending queries wait in a queue until there is enough compute resources available to begin execution.
You can set thresholds on CPU usage, memory usage, and query concurrency to trigger query queues.
Enable query queues
Query queues are disabled by default. You can enable query queues for INSERT loading, SELECT queries, and statistics queries by setting corresponding global session variables.
- Enable query queues for loading tasks:
SET GLOBAL enable_query_queue_load = true;
- Enable query queues for SELECT queries:
SET GLOBAL enable_query_queue_select = true;
- Enable query queues for statistics queries:
SET GLOBAL enable_query_queue_statistic = true;
Specify resource thresholds
You can set the thresholds that trigger query queues via the following global session variables:
Variable | Default | Description |
---|---|---|
query_queue_concurrency_limit | 0 | The upper limit of concurrent queries on a BE. It takes effect only after being set greater than 0 . |
query_queue_mem_used_pct_limit | 0 | The upper limit of memory usage percentage on a BE. It takes effect only after being set greater than 0 . Range: [0, 1] |
query_queue_cpu_used_permille_limit | 0 | The upper limit of CPU usage permille (CPU usage * 1000) on a BE. It takes effect only after being set greater than 0 . Range: [0, 1000] |
NOTE
By default, BE reports resource usage to FE at one-second intervals. You can change this interval by setting the BE configuration item
report_resource_usage_interval_ms
.
Configure query queues
You can set the capacity of a query queue and the maximum timeout of queries in queues via the following global session variables:
Variable | Default | Description |
---|---|---|
query_queue_max_queued_queries | 0 | The upper limit of queries in a queue. When this threshold is reached, incoming queries are rejected. It takes effect only after being set greater than 0 . |
query_queue_pending_timeout_second | 300 | The maximum timeout of a pending query in a queue. When this threshold is reached, the corresponding query is rejected. Unit: second. |
View query queue statistics
You can view the statistics of query queues via the following ways:
- Check the number of running queries, and memory and CPU usages in BE nodes using SHOW PROC:
mysql> SHOW PROC '/backends'\G
*************************** 1. row ***************************
...
NumRunningQueries: 0
MemUsedPct: 0.79 %
CpuUsedPct: 0.0 %
- Check if a query is in a queue (when
IsPending
istrue
) using SHOW PROCESSLIST:
mysql> SHOW PROCESSLIST;
+------+------+---------------------+-------+---------+---------------------+------+-------+-------------------+-----------+
| Id | User | Host | Db | Command | ConnectionStartTime | Time | State | Info | IsPending |
+------+------+---------------------+-------+---------+---------------------+------+-------+-------------------+-----------+
| 2 | root | xxx.xx.xxx.xx:xxxxx | | Query | 2022-11-24 18:08:29 | 0 | OK | SHOW PROCESSLIST | false |
+------+------+---------------------+-------+---------+---------------------+------+-------+-------------------+-----------+
Check the FE audit log file fe.audit.log. The field
PendingTimeMs
indicates the time that a query is in a queue, and its unit is milliseconds.Check the following FE metrics:
Metrics | Description |
---|---|
starrocks_fe_query_queue_pending | Number of pending queries in the queue. |
starrocks_fe_query_queue_total | Total number of queries that have been queued. |
starrocks_fe_query_queue_timeout | Number of timeout queries in the queue. |