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
timestampcolumn
info
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
timestampcan 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 the ingestion of records that are out-of-order (O3) by time. QuestDB detects and adjusts data ingestion for O3 data automatically and no manual configuration is required.
Advantages#
Electing 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.