CREATE MATERIALIZED VIEW

Creates a materialized view that stores pre-computed query results and refreshes incrementally as new data arrives. For conceptual overview, see Materialized Views.

Syntax

CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] viewName
[ WITH BASE baseTableName ]
[ REFRESH ( IMMEDIATE | MANUAL | EVERY interval ) [ DEFERRED ]
           [ START timestamp ] [ TIME ZONE timezone ]
           [ PERIOD ( LENGTH length [ TIME ZONE tz ] [ DELAY delay ] ) ]
           [ PERIOD ( SAMPLE BY INTERVAL ) ] ]
AS [ ( ] query [ ) ]
[ TIMESTAMP ( columnRef ) ]
[ PARTITION BY ( YEAR | MONTH | WEEK | DAY | HOUR ) [ TTL n timeUnit ] ]
[ OWNED BY ownerName ]

Where:

• interval: Duration like 1m, 10m, 1h, 1d
• timeUnit: HOURS | DAYS | WEEKS | MONTHS | YEARS
• query: Must contain SAMPLE BY or time-based GROUP BY

Parameters

Parameter	Description
viewName	Name for the materialized view
IF NOT EXISTS	Create only if view doesn't already exist
WITH BASE	Specify base table (required for JOINs)
REFRESH	Refresh strategy (default: IMMEDIATE)
DEFERRED	Skip initial refresh on creation
query	A SAMPLE BY or time-based GROUP BY query
TIMESTAMP	Designate timestamp column for the view
PARTITION BY	Partitioning unit for view storage
TTL	Retention period for view data
OWNED BY	Assign ownership (Enterprise)

Rules and defaults

Rule	Description
Query must aggregate	Requires SAMPLE BY or GROUP BY with designated timestamp
Default refresh	IMMEDIATE (refreshes after each base table transaction)
WITH BASE required	Must specify when query contains JOINs
PARTITION BY sizing	Should be larger than or equal to SAMPLE BY interval
PERIOD requires SAMPLE BY	The PERIOD clause only works with SAMPLE BY queries
EVERY minimum	Minimum timer interval is 1m

Valid clause combinations

Refresh	DEFERRED	PERIOD	Valid
IMMEDIATE	✓	✓	✓
MANUAL	✓	✓	✓
EVERY interval	✓	✓	✓
(none specified)	✗	✗	✓ (defaults to IMMEDIATE)

Basic example

Base table

CREATE TABLE trades (
  timestamp TIMESTAMP,
  symbol SYMBOL,
  price DOUBLE,
  amount DOUBLE
) TIMESTAMP(timestamp) PARTITION BY DAY;

Materialized view with hourly aggregation

CREATE MATERIALIZED VIEW trades_hourly AS
SELECT
  timestamp,
  symbol,
  avg(price) AS avg_price
FROM trades
SAMPLE BY 1h;

The view refreshes incrementally each time trades receives new data.

Refresh strategies

IMMEDIATE (default)

Refreshes incrementally after each base table transaction:

CREATE MATERIALIZED VIEW trades_hourly
REFRESH IMMEDIATE AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h;

Best for: Real-time dashboards where data freshness matters.

EVERY interval

Checks for new data and refreshes on a timer schedule:

CREATE MATERIALIZED VIEW trades_hourly
REFRESH EVERY 10m AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h;

Every 10 minutes, QuestDB checks if the base table has new data and performs an incremental refresh if needed.

With start time and timezone:

CREATE MATERIALIZED VIEW trades_hourly
REFRESH EVERY 1h START '2025-01-01T00:00:00Z' TIME ZONE 'Europe/Berlin' AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h;

Option	Description
EVERY interval	How often to check for updates (e.g., 10m, 1h)
START timestamp	When to begin the schedule
TIME ZONE	Timezone for schedule alignment

Best for: Reducing refresh overhead when real-time accuracy isn't required.

note

Minimum interval is 1m. For faster refresh, use IMMEDIATE.

MANUAL

Refreshes only when explicitly triggered:

CREATE MATERIALIZED VIEW trades_hourly
REFRESH MANUAL AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h;

Trigger refresh with REFRESH MATERIALIZED VIEW.

Best for: Full control over refresh timing, batch processing workflows.

DEFERRED

Skips the initial full refresh on creation. Applies to any strategy:

CREATE MATERIALIZED VIEW trades_hourly
REFRESH IMMEDIATE DEFERRED AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h;

The view remains empty until:

• IMMEDIATE: Next base table transaction
• EVERY: Next scheduled refresh time
• MANUAL: Explicit REFRESH command

PERIOD clause

For data arriving at fixed intervals (e.g., end-of-day prices), use PERIOD to define an in-flight time window that won't refresh until complete.

Full PERIOD syntax

CREATE MATERIALIZED VIEW trades_daily
REFRESH PERIOD (LENGTH 1d TIME ZONE 'Europe/London' DELAY 2h) AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1d;

Option	Description
LENGTH	Period duration (e.g., 1d)
TIME ZONE	Timezone for period boundaries
DELAY	Grace period before period closes (e.g., 2h for late data)

In this example, each day's data refreshes at 2AM London time.

Compact PERIOD syntax

Matches period to the SAMPLE BY interval:

CREATE MATERIALIZED VIEW trades_hourly
REFRESH PERIOD (SAMPLE BY INTERVAL) AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades
SAMPLE BY 1h ALIGN TO CALENDAR TIME ZONE 'Europe/London';

Ignores the latest incomplete interval, reducing refresh transactions during high-velocity ingestion.

PERIOD with other strategies

Combine PERIOD with EVERY or MANUAL:

Period with timer refresh

CREATE MATERIALIZED VIEW hourly_stats
REFRESH EVERY 15m PERIOD (LENGTH 1h DELAY 5m) AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h;

This configuration:

• Checks for updates every 15 minutes (EVERY 15m)
• Processes data in 1-hour chunks (LENGTH 1h)
• Waits 5 minutes after each hour ends before refreshing it (DELAY 5m)

The DELAY allows late-arriving data to be included before the period closes.

Period with manual refresh

CREATE MATERIALIZED VIEW trades_daily
REFRESH MANUAL PERIOD (LENGTH 1d TIME ZONE 'UTC' DELAY 1h) AS
SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1d;

With MANUAL, refresh only occurs when you run REFRESH MATERIALIZED VIEW explicitly.

WITH BASE (for JOINs)

When querying multiple tables, specify which table triggers refresh:

CREATE MATERIALIZED VIEW trades_with_metadata
WITH BASE trades AS
SELECT
  t.timestamp,
  t.symbol,
  m.description,
  avg(t.price) AS avg_price
FROM trades t
JOIN instruments m ON t.symbol = m.symbol
SAMPLE BY 1h;

Only changes to trades trigger refresh. Changes to instruments do not.

Partitioning

Specify storage partitioning with PARTITION BY:

CREATE MATERIALIZED VIEW trades_hourly AS (
  SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h
) PARTITION BY DAY;

Options: YEAR, MONTH, WEEK, DAY, HOUR

If omitted, partitioning is inferred from SAMPLE BY.

warning

Partitioning cannot be changed after creation.

TTL (Time-To-Live)

Limit data retention with TTL:

CREATE MATERIALIZED VIEW trades_hourly AS (
  SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h
) PARTITION BY DAY TTL 7 DAYS;

Time units: HOURS, DAYS, WEEKS, MONTHS, YEARS

The view's TTL is independent of the base table's TTL. See TTL documentation for details.

Storage Policy

note

Storage policies are available in QuestDB Enterprise only.

A storage policy automates the partition lifecycle by defining when partitions are converted to Parquet locally, when native data is removed, and when local copies are dropped. Place the STORAGE POLICY(...) clause after PARTITION BY:

With storage policy (Enterprise)

CREATE MATERIALIZED VIEW trades_hourly AS (
  SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h
) PARTITION BY DAY
  STORAGE POLICY(TO PARQUET 7d, DROP NATIVE 14d);

A storage policy supports up to four settings: TO PARQUET, DROP NATIVE, DROP LOCAL, and DROP REMOTE. All are optional. TTL values must be in ascending order.

To modify a storage policy after creation, see ALTER MATERIALIZED VIEW SET STORAGE POLICY.

note

In QuestDB Enterprise, TTL is deprecated. Use STORAGE POLICY instead. If a materialized view has a TTL set, remove it before setting a storage policy.

Complete example

Putting it all together:

Fully specified materialized view

CREATE MATERIALIZED VIEW IF NOT EXISTS trades_hourly_stats
WITH BASE trades
REFRESH EVERY 15m
  START '2025-01-01T00:00:00Z'
  TIME ZONE 'UTC'
  PERIOD (LENGTH 1h DELAY 5m)
AS (
  SELECT
    timestamp,
    symbol,
    avg(price) AS avg_price,
    sum(amount) AS total_volume
  FROM trades
  SAMPLE BY 1h
)
PARTITION BY DAY TTL 30 DAYS;

This creates a view that:

• Checks for updates every 15 minutes (EVERY 15m)
• Processes data in 1-hour chunks, waiting 5 minutes for late data (PERIOD)
• Aggregates from trades table (WITH BASE trades)
• Stores hourly averages and volumes (SAMPLE BY 1h)
• Keeps 30 days of data (TTL 30 DAYS)

Metadata

Query view metadata with materialized_views():

SELECT view_name, base_table_name, view_status, last_refresh_finish_timestamp
FROM materialized_views();

See meta functions for all available columns.

Query constraints

Materialized view queries must:

• Use SAMPLE BY or GROUP BY with designated timestamp
• Not use FROM-TO, FILL, or ALIGN TO FIRST OBSERVATION
• Not use non-deterministic functions (now(), rnd_*)

See query constraints for the full list.

Permissions (Enterprise)

Creating and managing materialized views requires specific permissions.

Required permissions

Permission	Level	Required for
CREATE MATERIALIZED VIEW	Database (global)	Creating a materialized view
SELECT	Table/Column (base table)	All columns referenced in the view query
DROP MATERIALIZED VIEW	Materialized view	Dropping the view
REFRESH MATERIALIZED VIEW	Materialized view	Manually refreshing the view

Owner permissions

When you create a materialized view, you automatically receive all permissions on it (including DROP MATERIALIZED VIEW and REFRESH MATERIALIZED VIEW) with the GRANT option.

OWNED BY clause

Assign ownership to a user, group, or service account:

CREATE GROUP analysts;
CREATE MATERIALIZED VIEW trades_hourly AS (
  SELECT timestamp, symbol, avg(price) AS avg_price FROM trades SAMPLE BY 1h
) OWNED BY analysts;

note

External users (authenticated via external identity providers) must specify the OWNED BY clause when creating materialized views.

Permission examples

Grant permission to create materialized views

GRANT CREATE MATERIALIZED VIEW TO user1;

Grant SELECT on base table (required to create view from it)

GRANT SELECT ON trades TO user1;

Grant permission to refresh a specific view

GRANT REFRESH MATERIALIZED VIEW ON trades_hourly TO user1;

Grant permission to drop a specific view

GRANT DROP MATERIALIZED VIEW ON trades_hourly TO user1;

Errors

Error	Cause
materialized view already exists	View exists and IF NOT EXISTS not specified
base table does not exist	Referenced table doesn't exist
query is not supported	Query doesn't meet constraints (missing SAMPLE BY, uses FILL, etc.)
permission denied	Missing required permission (Enterprise)

See also

• Materialized views concept
• REFRESH MATERIALIZED VIEW
• DROP MATERIALIZED VIEW
• ALTER MATERIALIZED VIEW SET REFRESH
• ALTER MATERIALIZED VIEW SET STORAGE POLICY
• ALTER MATERIALIZED VIEW SET TTL