Hologres:Usage and billing

Prerequisites

To query Serverless Computing resource consumption from slow query logs, you need one of the following permission levels.

To view data scan volume across all databases in an instance:

• Option 1 — Superuser permission:

  -- Replace "Alibaba Cloud account ID" with the actual username.
  -- For RAM users, prepend the account ID with "p4_".
  ALTER USER "Alibaba Cloud account ID" SUPERUSER;

• Option 2 — pg_read_all_stats group membership (regular users who need full log access must contact a Superuser for authorization):

  GRANT pg_read_all_stats TO "Alibaba Cloud account ID";           -- Standard PostgreSQL authorization model
  CALL spm_grant('pg_read_all_stats', 'Alibaba Cloud account ID'); -- SPM
  CALL slpm_grant('pg_read_all_stats', 'Alibaba Cloud account ID'); -- SLPM

To view data scan volume for the current database only:

• Enable the simple permission model (SPM) or the schema-level simple permission model (SLPM), then add the user to the db_admin group:

  CALL spm_grant('<db_name>_admin', 'Alibaba Cloud account ID');  -- SPM
  CALL slpm_grant('<db_name>.admin', 'Alibaba Cloud account ID'); -- SLPM

• Regular users can query their own data scan volume within databases associated with their account.

For more information, see Permission management overview.

Query resource consumption for a single SQL statement

The following query returns detailed resource consumption for each Serverless Computing job, including the CUs allocated and the time the job spent waiting in the queue.

SELECT
    *,
    queue_time_ms,                    -- Time the SQL spent waiting in the Serverless Computing queue (ms)
    serverless_allocated_cores,       -- Number of CUs allocated to this SQL job
    serverless_resource_used_time_ms, -- Duration the SQL actually used Serverless Computing resources (ms)
    (serverless_allocated_cores::DECIMAL(38, 4)) * (serverless_resource_used_time_ms::DECIMAL(38, 4)) AS serverless_cums
FROM
    hologres.hg_serverless_computing_query_log;

The serverless_cums column shows the raw CU·millisecond value for each job. Divide by 1000 * 60 * 60 to convert to CU·H.

Query total resource consumption over a time range

The following query calculates total CU·H consumed by all successfully executed Serverless Computing jobs within a specified time window. Adjust the query_end range to match the period you want to analyze.

SELECT
    (SUM((serverless_allocated_cores::DECIMAL(38, 4)) * (serverless_resource_used_time_ms::DECIMAL(38, 4))) / 1000 / 60 / 60)::bigint AS serverless_cuh
FROM
    hologres.hg_serverless_computing_query_log
WHERE
    status = 'SUCCESS'
    AND serverless_allocated_cores IS NOT NULL
    AND serverless_resource_used_time_ms IS NOT NULL
    AND query_end BETWEEN '2024-05-01 00:00:00' AND '2024-05-31 24:00:00'; -- Specify time range

The result is the estimated Serverless Computing resource consumption for that period in CU·H.

Configure the daily limit

-- Set limit for a database
ALTER DATABASE <db_name> SET hg_serverless_computing_daily_max_cuh_usage_threshold = <value>;

-- Set limit for a user
ALTER USER <user_name> SET hg_serverless_computing_daily_max_cuh_usage_threshold = <value>;

Hologres tracks daily usage based on the default time zone of the database. To check the database time zone, run the following commands in the same session:

-- Reset time zone to avoid influence from client or user settings
RESET timezone;

-- Show the database's default time zone
SHOW timezone;

When to set a limit:

• If Serverless Computing is already part of your regular workload, review the output of Query total resource consumption over a time range to determine an appropriate daily cap.

• If you are new to Serverless Computing, wait until your workload stabilizes before setting a daily limit.

Configure behavior when the limit is exceeded

By default, when the daily limit is reached, SQL jobs automatically fall back to using instance resources rather than Serverless Computing. Before executing each SQL statement, Hologres compares the current daily Serverless usage against the configured limit for the user or database. If the limit is reached, the statement runs on instance resources instead.

To disable automatic fallback and fail queries immediately when the limit is exceeded, run the following commands (Superuser only):

-- Set at database level
ALTER DATABASE <db_name> SET hg_serverless_computing_enable_fallback_when_exceed_cuh_threshold = false;

-- Set at user level
ALTER USER <user_name> SET hg_serverless_computing_enable_fallback_when_exceed_cuh_threshold = false;

Behavior when the limit is exceeded:

Cost Analysis

You can use the Cost > Cost Analysis module in Expenses and Costs to monitor and analyze the billing of Hologres compute resources.

1. Log on to Expenses and Costs. In the navigation pane on the left, click Cost > Cost Analysis.

2. On the Cost Analysis page, in the Condition List > Classification Dimension section on the right, select Billing Item. Then, select a Cost Type and Time Granularity as needed.

3. In the Filter Conditions section on the right, select the appropriate Billing Item based on your resource type.

For more information, see Cost Analysis.

Spending alerts

Use Expenses and Costs to manage budgets and set alerts for pay-as-you-go spending on specific products in specific regions. For more information, see Expense Alerts.

Single SQL execution duration alert

Hologres supports monitoring for Serverless Computing metrics. Create alert rules based on your business needs to avoid unexpected charges.

For example, for the metric Longest duration among running Serverless Computing queries, the following alert rule is recommended:

Warning: The longest duration among running Serverless Computing queries is >= 3,600,000 milliseconds for 5 consecutive periods (1 period = 1 minute).

For more information, see Monitoring and alerting best practices.