ClickHouse table schemas

ClickHouse database is used as Prisme Analytics events store. This page document schemas of Prisme Analytics tables.

Sessions table

Sessions are stored in sessions table with the following schemas:

Column name	Type	Description
domain	String	Domain from which events originate.
session_timestamp	DateTime (ALIAS)	Date and time at which session was created.
entry_timestamp	DateTime (ALIAS)	Same as session_timestamp.
entry_path	String	Path of this session's first viewed page.
exit_timestamp	DateTime	Date and time of this session's last viewed page.
exit_path	String	Path of this session's last viewed page?
visitor_id	String	Unique visitor identifier.
is_anon	Bool	Whether the visitor is anonymous.
session_uuid	UUID	UUIDv7 associated to this session.
session_id	UInt128 (ALIAS)	session_uuid as a UInt128, use this field if you want to sort on session_uuid.
operating_system	LowCardinality(String)	Visitor's Operating System (OS)
browser_family	LowCardinality(String)	Visitor's browser family (e.g. Chrome, Firefox, etc)
device	LowCardinality(String)	Visitor's device name.
referrer_domain	String	Referrer of entry page.
country_code	LowCardinality(String)	ISO 3166-1 alpha-2 – two-letter country codes. (XX is used when country is unknown)
utm_source	String	UTM source parameter.
utm_medium	String	UTM medium parameter.
utm_campaign	String	UTM campaign parameter.
utm_term	String	UTM term parameter.
utm_content	String	UTM content parameter.
version	UInt16 (ALIAS)	Version field of VersionedCollapsingMergeTree
pageview_count	UInt16 (ALIAS version)	Number of pageviews associated to this session.
is_bounce	UInt16 (ALIAS)	Whether this session is a bounce or not.

Events tables

Page views events

Page views events are stored in pageviews table with the following schemas:

Column name	Type	Description
timestamp	DateTime	Date and time at which pageview events occurred.
domain	String	Domain from which events originate.
path	String	Viewed page path.
visitor_id	String	The visitor ID.
session_uuid	UUID	The session UUIDv7.

Custom events

Custom events are stored in events_custom table with the following schemas:

Column name	Type	Description
timestamp	DateTime	Date and time at which pageview events occurred.
domain	String	Domain from which events originate.
path	String	Viewed page path.
visitor_id	String	A visitor ID.
session_uuid	UUID	The session UUIDv7.
name	String	Name of the event.
keys	Array(String)	Top level keys of event JSON object.
values	Array(String)	Top level values of event JSON object.

Prisme stores custom events JSON in two columns, keys and values, instead of a single String column to improve query performances. Unfortunately, this is not practical, that's why we provide a event_property helper function.

tip

It is recommended to avoid nested JSON objects as it may impact performance at query time.

Let's suppose you're website send click events with two properties, x and y, cursor position on X and Y axis respectively:

document.addEventListener("click", (ev) => {
  window.prisme.trigger("click", { x: ev.clientX, y: ev.clientY });
});

You want to retrieve clicks at position (128, 64).

SELECT * FROM prisme.events_custom
  WHERE name = 'click'
  AND event_property('x') == '128'
  AND event_property('y') == '64';

note

Properties are compared against a String value as event_property helper function always returns a JSON string. You can cast value if needed using appropriate type conversion function.

Now let's say we want to retrieve clicks in the first 100 pixels on Y axis. We need an integer value.

In that case, a simple cast is the more appropriate:

SELECT * FROM prisme.events_custom
  WHERE name = 'click'
  AND toInt64OrZero(event_property('y')) <= 100;

If you're dealing with a more complex case, you may need more specialized JSON functions. You can find the list of all ClickHouse JSON functions here.