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.

A designated timestamp is elected by using the timestamp(columnName) function:

  • during a CREATE TABLE operation
  • during a SELECT operation (dynamic timestamp)
  • when ingesting data via ILP, for tables that do not already exist in QuestDB, partitions are applied automatically by day by default with a timestamp column
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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.

Properties#

  • Only a column of type timestamp can be elected as a designated timestamp.
  • Only one column can be elected for a given table.

Out-of-order policy#

As 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.

Advantages#

Electing a designated timestamp allows you to: