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96 lines
4.1 KiB
ReStructuredText
96 lines
4.1 KiB
ReStructuredText
Quotas
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======
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Quotas allow you to limit resource usage over a period of time, or simply track the use of resources.
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Quotas are set up in the user config. This is usually ``users.xml``.
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The system also has a feature for limiting the complexity of a single query (see the section "Restrictions on query complexity").
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In contrast to query complexity restrictions, quotas:
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* place restrictions on a set of queries that can be run over a period of time, instead of limiting a single query.
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* account for resources spent on all remote servers for distributed query processing.
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Let's look at the section of the ``users.xml`` file that defines quotas.
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.. code-block:: xml
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<!-- Quotas. -->
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<quotas>
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<!-- Quota name. -->
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<default>
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<!-- Restrictions for a time period. You can set multiple time intervals with various restrictions. -->
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<interval>
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<!-- Length of time. -->
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<duration>3600</duration>
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<!-- No restrictions. Just collect data for the specified time interval. -->
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<queries>0</queries>
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<errors>0</errors>
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<result_rows>0</result_rows>
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<read_rows>0</read_rows>
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<execution_time>0</execution_time>
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</interval>
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</default>
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By default, the quota just tracks resource consumption for each hour, without limiting usage.
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.. code-block:: xml
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<statbox>
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<!-- Restrictions for a time period. You can set multiple time intervals with various restrictions. -->
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<interval>
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<!-- Length of time.-->
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<duration>3600</duration>
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<queries>1000</queries>
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<errors>100</errors>
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<result_rows>1000000000</result_rows>
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<read_rows>100000000000</read_rows>
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<execution_time>900</execution_time>
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</interval>
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<interval>
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<duration>86400</duration>
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<queries>10000</queries>
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<errors>1000</errors>
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<result_rows>5000000000</result_rows>
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<read_rows>500000000000</read_rows>
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<execution_time>7200</execution_time>
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</interval>
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</statbox>
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For the ``statbox`` quota, restrictions are set for every hour and for every 24 hours (86,400 seconds). The time interval is counted starting from an implementation-defined fixed moment in time. In other words, the 24-hour interval doesn't necessarily begin at midnight.
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When the interval ends, all collected values are cleared. For the next hour, the quota calculation starts over.
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Let's examine the amounts that can be restricted:
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``queries`` - The overall number of queries.
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``errors`` - The number of queries that threw exceptions.
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``result_rows`` - The total number of rows output in results.
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``read_rows`` - The total number of source rows retrieved from tables for running a query, on all remote servers.
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``execution_time`` - The total time of query execution, in seconds (wall time).
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If the limit is exceeded for at least one time interval, an exception is thrown with a text about which restriction was exceeded, for which interval, and when the new interval begins (when queries can be sent again).
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Quotas can use the "quota key" feature in order to report on resources for multiple keys independently. Here is an example of this:
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.. code-block:: xml
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<!-- For the global report builder. -->
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<web_global>
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<!-- keyed - the quota_key "key" is passed in the query parameter, and the quota is tracked separately for each key value.
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For example, you can pass a Metrica username as the key, so the quota will be counted separately for each username.
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Using keys makes sense only if quota_key is transmitted by the program, not by a user.
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You can also write <keyed_by_ip /> so the IP address is used as the quota key.
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(But keep in mind that users can change the IPv6 address fairly easily.) -->
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<keyed />
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The quota is assigned to users in the ``users`` section of the config. See the section "Access rights".
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For distributed query processing, the accumulated amounts are stored on the requestor server. So if the user goes to another server, the quota there will "start over".
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When the server is restarted, quotas are reset.
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