Meta functions

These functions provide instance-level information and table, column and partition information including metadata. They are particularly useful for learning useful information about your instance, including:

• Designated timestamp columns
• Attached, detached, or attachable partitions
• Partition storage size on disk
• Running SQL commands

build

Arguments:

• build() does not require arguments.

Return value:

Returns a string with the current QuestDB version and hash.

Examples:

SELECT build();

build
Build Information: QuestDB 7.3.5, JDK 17.0.7, Commit Hash 460b817b0a3705c5633619a8ef9efb5163f1569c

functions

Arguments:

• functions() does not require arguments.

Return value:

Returns all available database functions.

Examples:

functions();

name	signature	signature_translated	runtime_constant	type
or	or(TT)	or(boolean, boolean)	FALSE	STANDARD
and	and(TT)	and(boolean, boolean)	FALSE	STANDARD
not	not(T)	not(boolean)	FALSE	STANDARD

query_activity

Arguments:

• query_activity() does not require arguments.

Return value:

Returns metadata on running SQL queries, including columns such as:

• query_id - identifier of the query that can be used with cancel query command or cancelQuery() function
• worker_id - identifier of worker thread that initiated query processing. Note that many multithreaded queries also run on other workers
• worker_pool - name of worker pool used to execute the query
• username - name of user executing the query
• query_start - timestamp of when query started
• state_change - timestamp of latest query state change, such as a cancellation
• state - state of running query, can be active or cancelled
• query - text of sql query

Examples:

SELECT * FROM query_activity();

query_id	worker_id	worker_pool	username	query_start	state_change	state	query
62179	5	shared	bob	2024-01-09T10:03:05.557397Z	2024-01-09T10:03:05.557397	active	select * from query_activity()
57777	6	shared	bob	2024-01-09T08:58:55.988017Z	2024-01-09T08:58:55.988017Z	active	SELECT symbol,approx_percentile(price, 50, 2) from trades

memory_metrics

Arguments:

• memory_metrics() does not require arguments.

Return value:

Returns granular memory metrics.

Examples:

memory_metrics();

memory_tag	bytes
TOTAL_USED	142624730
RSS	328609792
MMAP_DEFAULT	196728
NATIVE_DEFAULT	256
MMAP_O3	0
NATIVE_O3	96

reader_pool

Arguments:

• reader_pool() does not require arguments.

Return value:

Returns information about the current state of the reader pool in QuestDB. The reader pool is a cache of table readers that are kept open to speed up subsequent reads from the same table. The returned information includes the table name, the ID of the thread that currently owns the reader, the timestamp of the last time the reader was accessed, and the current transaction ID with which the reader is associated.

Examples:

SELECT * FROM reader_pool();

table_name	owner_thread_id	last_access_timestamp	current_txn
sensors	null	2023-12-01T19:28:14.311703Z	1

writer_pool

Arguments:

• writer_pool() does not require arguments.

Return value:

Returns information about the current state of the writer pool in QuestDB. The writer pool is a cache of table writers that are kept open to speed up subsequent writes to the same table. The returned information includes the table name, the ID of the thread that currently owns the writer, the timestamp of the last time the writer was accessed, and the reason for the ownership.

Examples:

SELECT * FROM writer_pool();

table_name	owner_thread_id	last_access_timestamp	ownership_reason
sys.column_versions_purge_log	1	2023-12-01T18:50:03.412468Z	QuestDB system
telemetry_config	1	2023-12-01T18:50:03.470604Z	telemetryConfig
telemetry	1	2023-12-01T18:50:03.464501Z	telemetry
sys.telemetry_wal	1	2023-12-01T18:50:03.467924Z	telemetry
example_table	null	2023-12-01T20:33:33.270984Z	null

current database, schema, or user

current_database(), current_schema(), and current_user() are standard SQL functions that return information about the current database, schema, schemas, and user, respectively.

-- Get the current database
SELECT current_database();

-- Get the current schema
SELECT current_schema();

-- Get the current user
SELECT current_user();

Each of these functions returns a single value, so you can use them in a SELECT statement without any arguments.

tables

tables() returns metadata and real-time statistics for all tables in the database, including write activity, WAL status, and performance metrics.

Arguments:

• tables() does not require arguments.

Return value:

Returns a table with the following columns:

Basic table information

Column	Type	Description
id	INT	Internal table ID
table_name	STRING	Table name
designatedTimestamp	STRING	Name of the designated timestamp column, or null
partitionBy	STRING	Partition strategy: NONE, HOUR, DAY, WEEK, MONTH, YEAR
walEnabled	BOOLEAN	Whether WAL (Write-Ahead Log) is enabled
dedup	BOOLEAN	Whether deduplication is enabled
ttlValue	INT	TTL (Time-To-Live) value
ttlUnit	STRING	TTL unit: HOUR, DAY, WEEK, MONTH, YEAR
matView	BOOLEAN	Whether this is a materialized view
directoryName	STRING	Directory name on disk (includes (->) suffix for symlinks)
maxUncommittedRows	INT	Table's maxUncommittedRows setting
o3MaxLag	LONG	Table's o3MaxLag setting in microseconds

note

(->) means the table was created using the IN VOLUME clause.

Table metrics (table_* prefix)

Column	Type	Description
table_suspended	BOOLEAN	Whether a WAL table is suspended (false for non-WAL tables)
table_row_count	LONG	Approximate row count at last tracked write
table_max_timestamp	TIMESTAMP	Approximate timestamp of last TableWriter commit
table_txn	LONG	TableWriter transaction number at last tracked write
table_memory_pressure_level	INT	Memory pressure: 0 (none), 1 (reduced parallelism), 2 (backoff). null for non-WAL
table_write_amp_count	LONG	Total write amplification samples recorded
table_write_amp_p50	DOUBLE	Median write amplification ratio
table_write_amp_p90	DOUBLE	90th percentile ratio
table_write_amp_p99	DOUBLE	99th percentile ratio
table_write_amp_max	DOUBLE	Maximum ratio
table_merge_rate_count	LONG	Total merge throughput samples recorded
table_merge_rate_p50	LONG	Median throughput in rows/second
table_merge_rate_p90	LONG	Throughput that 90% of jobs exceeded (slowest 10%)
table_merge_rate_p99	LONG	Throughput that 99% of jobs exceeded (slowest 1%)
table_merge_rate_max	LONG	Maximum throughput in rows/second

Write amplification measures O3 (out-of-order) merge overhead as physicalRowsWritten / logicalRows. A ratio of 1.0 means no amplification. Higher values indicate O3 merge overhead.

note

Merge rate P99 shows the lowest throughput (worst performance), not the highest.

WAL metrics (wal_* prefix)

Column	Type	Description
wal_pending_row_count	LONG	Rows written to WAL but not yet applied to table
dedup_row_count_since_start	LONG	Cumulative rows removed by deduplication (since server start)
wal_txn	LONG	WAL sequencer transaction number (WAL tables only)
wal_max_timestamp	TIMESTAMP	Max data timestamp from last WAL commit (WAL tables only)
wal_tx_count	LONG	Total WAL transactions recorded (since server start)
wal_tx_size_p50	LONG	Median transaction size in rows
wal_tx_size_p90	LONG	90th percentile transaction size in rows
wal_tx_size_p99	LONG	99th percentile transaction size in rows
wal_tx_size_max	LONG	Maximum transaction size in rows

Replica metrics (replica_* prefix)

These columns are populated on replicas only via replication download tracking:

Column	Type	Description
replica_batch_count	LONG	Total download batches recorded
replica_batch_size_p50	LONG	Median batch size in rows
replica_batch_size_p90	LONG	90th percentile batch size
replica_batch_size_p99	LONG	99th percentile batch size
replica_batch_size_max	LONG	Maximum batch size
replica_more_pending	BOOLEAN	true if the last download batch was limited and more data is available

On primary instances, these columns will be 0 or false.

Data precision and limitations

These values are approximations, not precise real-time metrics:

• Null when not tracked: Values are null for tables not written to since server start, or evicted from the tracker
• Writer stats updated on pool return: table_row_count, table_max_timestamp, table_txn are captured when TableWriter returns to the pool, not on every commit. A writer held for a long time won't update these columns until released.
• WAL stats updated in real-time:
  • On WAL commit: wal_pending_row_count (incremented), wal_txn, wal_max_timestamp, wal_tx_size_* histogram
  • On WAL apply: wal_pending_row_count (decremented), dedup_row_count_since_start, table_write_amp_*, table_merge_rate_*
• LRU eviction: Tracker maintains bounded memory (default 1000 tables). Least recently written tables are evicted when capacity is exceeded
• Startup hydration: Values are hydrated from table metadata (TxReader) on startup, but diverge as writes occur

Non-WAL tables: wal_txn, wal_max_timestamp, wal_pending_row_count, dedup_row_count_since_start, table_memory_pressure_level, and histogram columns are null or 0.

WAL tables: All columns populated when tracked. wal_max_timestamp reflects the max data timestamp from the WAL transaction, not wall-clock time.

Configuration

Property	Default	Description
cairo.recent.write.tracker.capacity	1000	Maximum number of tables tracked

Tables exceeding this capacity are evicted based on least recent write activity.

Examples:

List all tables

tables();

id	table_name	designatedTimestamp	partitionBy	walEnabled	directoryName	dedup	ttlValue	ttlUnit	matView
1	my_table	ts	DAY	false	my_table	false	0	HOUR	false
2	device_data	null	NONE	false	device_data	false	0	HOUR	false
3	short_lived	null	HOUR	false	short_lived (->)	false	1	HOUR	false

All tables with a daily partitioning strategy

tables() WHERE partitionBy = 'DAY';

id	table_name	designatedTimestamp	partitionBy	walEnabled	directoryName	dedup	ttlValue	ttlUnit	matView
1	my_table	ts	DAY	true	my_table	false	0	HOUR	false

Recently written tables

SELECT table_name, table_row_count, table_max_timestamp
FROM tables()
WHERE table_max_timestamp IS NOT NULL
ORDER BY table_max_timestamp DESC
LIMIT 10;

WAL apply lag

SELECT
    table_name,
    wal_txn - table_txn AS pending_txns,
    wal_pending_row_count
FROM tables()
WHERE walEnabled
  AND wal_txn IS NOT NULL
  AND wal_txn > table_txn
ORDER BY pending_txns DESC;

Suspended tables

SELECT table_name, table_suspended, table_memory_pressure_level
FROM tables()
WHERE walEnabled AND table_suspended;

Memory pressure

SELECT table_name, table_memory_pressure_level
FROM tables()
WHERE table_memory_pressure_level > 0
ORDER BY table_memory_pressure_level DESC;

Deduplication activity

SELECT table_name, dedup_row_count_since_start, wal_tx_count,
       dedup_row_count_since_start * 100.0 / NULLIF(wal_tx_count, 0) AS dedup_ratio
FROM tables()
WHERE dedup_row_count_since_start > 0
ORDER BY dedup_row_count_since_start DESC;

Large transactions

SELECT table_name, wal_tx_count, wal_tx_size_p50, wal_tx_size_p99, wal_tx_size_max
FROM tables()
WHERE walEnabled AND wal_tx_count > 0
ORDER BY wal_tx_size_p99 DESC;

High variance (spiky workloads)

SELECT table_name, wal_tx_size_p50, wal_tx_size_max,
       wal_tx_size_max / NULLIF(wal_tx_size_p50, 0) AS spike_ratio
FROM tables()
WHERE walEnabled AND wal_tx_size_max > wal_tx_size_p50 * 10;

High write amplification (O3 overhead)

SELECT table_name,
       table_write_amp_count,
       table_write_amp_p50,
       table_write_amp_p99,
       table_write_amp_max
FROM tables()
WHERE walEnabled
  AND table_write_amp_p50 > 2.0
ORDER BY table_write_amp_p99 DESC;

Slow merge performance

SELECT table_name,
       table_merge_rate_p99 AS slowest_throughput,
       table_merge_rate_p50 AS median_throughput,
       table_merge_rate_max AS best_throughput
FROM tables()
WHERE walEnabled
  AND table_merge_rate_count > 0
ORDER BY table_merge_rate_p99 ASC;

Replica download statistics

SELECT table_name, replica_batch_count, replica_batch_size_p50,
       replica_batch_size_p90, replica_batch_size_max, replica_more_pending
FROM tables()
WHERE replica_batch_count > 0
ORDER BY replica_batch_count DESC;

Table configuration overview

SELECT table_name,
       partitionBy,
       walEnabled,
       dedup,
       maxUncommittedRows,
       o3MaxLag / 1000000 AS o3MaxLagSeconds
FROM tables()
WHERE walEnabled
ORDER BY table_name;

Health dashboard query

SELECT
    table_name,
    table_row_count,
    wal_pending_row_count,
    CASE
        WHEN table_suspended THEN 'SUSPENDED'
        WHEN table_memory_pressure_level = 2 THEN 'BACKOFF'
        WHEN table_memory_pressure_level = 1 THEN 'PRESSURE'
        ELSE 'OK'
    END AS status,
    wal_txn - table_txn AS lag_txns,
    table_write_amp_p50 AS write_amp,
    table_merge_rate_p99 AS slowest_merge
FROM tables()
WHERE walEnabled
ORDER BY
    table_suspended DESC,
    table_memory_pressure_level DESC,
    wal_pending_row_count DESC;

table_storage

table_storage() - Returns information about the storage and structure of all user tables and materialized views in the database.

Provides detailed storage information about all user tables and materialized views within QuestDB. It returns one row per table, including information about partitioning, row counts, and disk usage.

• The table_storage() function excludes system tables; it only lists user-created tables.
• The diskSize value represents the total size of all files associated with the table on disk, including data, index, and metadata files.
• The partitionBy column indicates the partitioning strategy used for the table. It can be NONE if the table is not partitioned.

Return values:

The function returns the following columns:

• tableName (string): The name of the table or materialized view.
• walEnabled (boolean): Indicates whether Write-Ahead Logging (WAL) is enabled for the table.
• partitionBy (string): The partitioning type of the table (e.g., NONE, DAY, MONTH, YEAR, etc.).
• partitionCount (long): The number of partitions the table has.
• rowCount (long): The total number of rows in the table.
• diskSize (long): The total disk space used by the table, in bytes.

Examples:

Retrieve storage information for all tables.

Checking our demo tablesDemo this query

SELECT * FROM table_storage();

• The query retrieves storage details for all tables in the database.
• The diskSize column shows the total disk space used by each table in bytes.

tableName	walEnabled	partitionBy	partitionCount	rowCount	diskSize
trips	true	MONTH	126	1634599313	261536158948
AAPL_orderbook	true	HOUR	16	3024878	2149403527
weather	false	NONE	1	137627	9972598
trades	true	DAY	954	1000848308	32764798760
ethblocks_json	true	DAY	3328	20688364	28311960478

---

Filter tables with WAL enabled.

WAL only tablesDemo this query

SELECT tableName, rowCount, diskSize
FROM table_storage()
WHERE walEnabled = true;

tableName	rowCount	diskSize
trips	1634599313	261536158948
AAPL_orderbook	3024878	2149403527
trades	1000850255	32764804264
ethblocks_json	20688364	28311960478

---

Show tables partitioned by HOUR.

Show tables partitioned by hourDemo this query

SELECT tableName, partitionCount, rowCount
FROM table_storage()
WHERE partitionBy = 'HOUR';

wal_tables

note

For monitoring and observability, use tables() instead. tables() provides all the same information plus additional metrics (pending rows, memory pressure, deduplication stats, throughput histograms), and is fully in-memory. wal_tables() reads from disk and is less suitable for frequent polling.

wal_tables() returns the WAL status for all WAL tables or materialized views in the database.

Arguments:

• wal_tables() does not require arguments.

Return value:

Returns a table including the following information:

• name - table or materialized view name
• suspended - suspended status flag
• writerTxn - the last committed transaction in TableWriter (equivalent to table_txn in tables())
• writerLagTxnCount - the number of transactions that are kept invisible when writing to the table; these transactions will be eventually moved to the table data and become visible for readers (equivalent to wal_txn - table_txn)
• sequencerTxn - the last committed transaction in the sequencer (equivalent to wal_txn in tables())

Examples:

List all tables

wal_tables();

name	suspended	writerTxn	writerLagTxnCount	sequencerTxn
sensor_wal	false	2	1	4
weather_wal	false	3	0	3
test_wal	true	7	1	9

table_columns

table_columns('tableName') returns the schema of a table or a materialized view.

Arguments:

• tableName is the name of an existing table or materialized view as a string.

Return value:

Returns a table with the following columns:

• column - name of the available columns in the table
• type - type of the column
• indexed - if indexing is applied to this column
• indexBlockCapacity - how many row IDs to store in a single storage block on disk
• symbolCached - whether this symbol column is cached
• symbolCapacity - how many distinct values this column of symbol type is expected to have
• designated - if this is set as the designated timestamp column for this table
• upsertKey - if this column is a part of UPSERT KEYS list for table deduplication

For more details on the meaning and use of these values, see the CREATE TABLE documentation.

Examples:

Get all columns in a table

table_columns('my_table');

column	type	indexed	indexBlockCapacity	symbolCached	symbolCapacity	designated	upsertKey
symb	SYMBOL	true	1048576	false	256	false	false
price	DOUBLE	false	0	false	0	false	false
ts	TIMESTAMP	false	0	false	0	true	false
s	VARCHAR	false	0	false	0	false	false

Get designated timestamp column

SELECT column, type, designated FROM table_columns('my_table') WHERE designated = true;

column	type	designated
ts	TIMESTAMP	true

Get the count of column types

SELECT type, count() FROM table_columns('my_table');

type	count
SYMBOL	1
DOUBLE	1
TIMESTAMP	1
VARCHAR	1

table_partitions

table_partitions('tableName') returns information for the partitions of a table or a materialized view with the option to filter the partitions.

Arguments:

• tableName is the name of an existing table or materialized view as a string.

Return value:

Returns a table with the following columns:

• index - INTEGER, index of the partition (NaN when the partition is not attached)
• partitionBy - STRING, one of NONE, HOUR, DAY, WEEK, MONTH and YEAR
• name - STRING, name of the partition, e.g. 2023-03-14, 2023-03-14.detached, 2023-03-14.attachable
• minTimestamp - LONG, min timestamp of the partition (NaN when the table is not partitioned)
• maxTimestamp - LONG, max timestamp of the partition (NaN when the table is not partitioned)
• numRows - LONG, number of rows in the partition
• diskSize - LONG, size of the partition in bytes
• diskSizeHuman - STRING, size of the partition meant for humans to read (same output as function size_pretty)
• readOnly - BOOLEAN, true if the partition is attached via soft link
• active - BOOLEAN, true if the partition is the last partition, and whether we are writing to it (at least one record)
• attached - BOOLEAN, true if the partition is attached
• detached - BOOLEAN, true if the partition is detached (name of the partition will contain the .detached extension)
• attachable - BOOLEAN, true if the partition is detached and can be attached (name of the partition will contain the .attachable extension)

Examples:

Create table my_table

CREATE TABLE my_table AS (
    SELECT
        rnd_symbol('EURO', 'USD', 'OTHER') symbol,
        rnd_double() * 50.0 price,
        rnd_double() * 20.0 amount,
        to_timestamp('2023-01-01', 'yyyy-MM-dd') + x * 6 * 3600 * 100000L timestamp
    FROM long_sequence(700)
), INDEX(symbol capacity 32) TIMESTAMP(timestamp) PARTITION BY WEEK;

Get all partitions from my_table

table_partitions('my_table');

index	partitionBy	name	minTimestamp	maxTimestamp	numRows	diskSize	diskSizeHuman	readOnly	active	attached	detached	attachable
0	WEEK	2022-W52	2023-01-01 00:36:00.0	2023-01-01 23:24:00.0	39	98304	96.0 KiB	false	false	true	false	false
1	WEEK	2023-W01	2023-01-02 00:00:00.0	2023-01-08 23:24:00.0	280	98304	96.0 KiB	false	false	true	false	false
2	WEEK	2023-W02	2023-01-09 00:00:00.0	2023-01-15 23:24:00.0	280	98304	96.0 KiB	false	false	true	false	false
3	WEEK	2023-W03	2023-01-16 00:00:00.0	2023-01-18 12:00:00.0	101	83902464	80.0 MiB	false	true	true	false	false

Get size of a table in disk

SELECT size_pretty(sum(diskSize)) FROM table_partitions('my_table');

size_pretty
80.3 MB

Get active partition of a table

SELECT * FROM table_partitions('my_table') WHERE active = true;

index	partitionBy	name	minTimestamp	maxTimestamp	numRows	diskSize	diskSizeHuman	readOnly	active	attached	detached	attachable
3	WEEK	2023-W03	2023-01-16 00:00:00.0	2023-01-18 12:00:00.0	101	83902464	80.0 MiB	false	true	true	false	false

materialized_views

materialized_views() returns the list of all materialized views in the database.

Arguments:

• materialized_views() does not require arguments.

Return value:

Returns a table including the following information:

• view_name - materialized view name
• refresh_type - refresh strategy type
• base_table_name - base table name
• last_refresh_start_timestamp - last time when an incremental refresh for the view was started
• last_refresh_finish_timestamp - last time when an incremental refresh for the view finished
• view_sql - query used to populate view data
• view_table_dir_name - view directory name
• invalidation_reason - message explaining why the view was marked as invalid
• view_status - view status: 'valid', 'refreshing', or 'invalid'
• refresh_base_table_txn - the last base table transaction used to refresh the materialized view
• base_table_txn - the last committed transaction in the base table
• refresh_limit_value - how many units back in time the refresh limit goes
• refresh_limit_unit - how long each unit is
• timer_start - start date for the scheduled refresh timer
• timer_interval_value - how many interval units between each refresh
• timer_interval_unit - how long each unit is

Examples:

List all materialized views

materialized_views();

view_name	refresh_type	base_table_name	last_refresh_start_timestamp	last_refresh_finish_timestamp	view_sql	view_table_dir_name	invalidation_reason	view_status	refresh_base_table_txn	base_table_txn	refresh_limit_value	refresh_limit_unit	timer_start	timer_interval_value	timer_interval_unit
trades_OHLC_15m	immediate	trades	2025-05-30T16:40:37.562421Z	2025-05-30T16:40:37.568800Z	SELECT timestamp, symbol, first(price) AS open, max(price) as high, min(price) as low, last(price) AS close, sum(amount) AS volume FROM trades SAMPLE BY 15m	trades_OHLC_15m~27	null	valid	55141609	55141609	0	null	null	0	null
trades_latest_1d	immediate	trades	2025-05-30T16:40:37.554274Z	2025-05-30T16:40:37.562049Z	SELECT timestamp, symbol, side, last(price) AS price, last(amount) AS amount, last(timestamp) as latest FROM trades SAMPLE BY 1d	trades_latest_1d~28	null	valid	55141609	55141609	0	null	null	0	null

views

views() returns the list of all views in the database.

Arguments:

• views() does not require arguments.

Return value:

Returns a table including the following information:

• view_name - view name
• view_sql - query used to define the view (without CREATE VIEW wrapper)
• view_table_dir_name - internal directory name
• invalidation_reason - message explaining why the view was marked as invalid, empty if valid
• view_status - view status: valid or invalid
• view_status_update_time - timestamp of last status change

Examples:

List all views

views();

view_name	view_sql	view_table_dir_name	invalidation_reason	view_status	view_status_update_time
hourly_summary	SELECT ts, symbol, sum(qty) FROM trades SAMPLE BY 1h	hourly_summary~1		valid	2025-05-30T10:15:00.000000Z
price_view	SELECT symbol, last(price) FROM trades SAMPLE BY 1d	price_view~2		valid	2025-05-30T10:20:00.000000Z

Find invalid views

SELECT view_name, invalidation_reason
FROM views()
WHERE view_status = 'invalid';

List views ordered by name

SELECT * FROM views() ORDER BY view_name;

version/pg_catalog.version

version() or pg_catalog.version() returns the supported version of the PostgreSQL Wire Protocol.

Arguments:

• version() or pg_catalog.version() does not require arguments.

Return value:

Returns string.

Examples:

SELECT version();

--The above equals to:

SELECT pg_catalog.version();

version
PostgreSQL 12.3, compiled by Visual C++ build 1914, 64-bit, QuestDB

hydrate_table_metadata('table1', 'table2' ...)

`hydrate_table_metadata' re-reads table metadata from disk to update the static metadata cache.

warning

This function should only be used when directed by QuestDB support. Misuse could cause corruption of the metadata cache, requiring the database to be restarted.

Arguments:

A variable list of strings, corresponding to table names.

Alternatively, a single asterisk, '*', representing all tables.

Return value:

Returns boolean. true if successful, false if unsuccessful.

Examples:

Simply pass table names as arguments to the function.

SELECT hydrate_table_metadata('trades', 'trips');

hydrate_table_metadata
true

If you want to re-read metadata for all user tables, simply use an asterisk:

SELECT hydrate_table_metadata('*');

flush_query_cache()

`flush_query_cache' invalidates cached query execution plans.

Arguments:

• flush_query_cache() does not require arguments.

Return value:

Returns boolean. true if successful, false if unsuccessful.

Examples:

Flush cached query execution plans

SELECT flush_query_cache();

reload_config()

reload_config' reloads server configuration file's contents (server.conf`) without server restart. The list of reloadable settings can be found here.

Arguments:

• reload_config() does not require arguments.

Return value:

Returns boolean. true if any configuration properties were reloaded, false if none were reloaded.

Examples:

Edit server.conf and run reload_config:

Reload server configuration

SELECT reload_config();