Designated timestamp
QuestDB offers the option to elect a column as a designated timestamp. This allows you to specify which column the tables will be indexed by in order to leverage time-oriented language features and high-performance functionalities.
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Checking if tables contain a designated timestamp column can be done via the
tables()
and table_columns()
functions which are described in the
meta functions documentation page.
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Properties- Only a column of type
timestamp
can be elected as a designated timestamp. - Only one column can be elected for a given table.
- A designated timestamp is elected either:
- during table creation
- within a query using a timestamp function
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Out-of-order policyAs of version 6.0.0, QuestDB supports ingestion of records which are out-of-order (O3) by time. Configuring how often out-of-order data is committed is done via commit lag and row count.
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In versions prior to 6.0.0, when a column was elected as a designated timestamp, it would enforce an order policy and O3 inserts would be rejected. In other words, new timestamp values needed to be greater than or equal to the most recent timestamp in the column.
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AdvantagesElecting a designated timestamp allows you to:
- Partition tables by time range. For more information, see the partitions reference.
- Use time series joins such as
ASOF JOIN
. For more information, see the JOIN reference.