Working with metadata

You can work with metadata in Tengri in a number of ways.

System tables

The following system tables are available for the administrator to view.

Table `system.schemas`

Schemas metadata.

catalog_name — catalogue name
namespace — schema name

Table `system.tables`

Tables metadata.

catalog_name — catalogue name
table_namespace — table schema
table_name — table name
metadata_location — path to table metadata
previous_metadata_location — path to metadata of the previous version of the table

Table `system.query_log`

History of user queries.

id — query identifier
username — name of the user executing the query
query — query text
status — query status
started_at — query start time
finished_at — the time when the query execution ends
duration_ms — query execution duration
error_message — error message when executing the query
worker_pool — name of the compute pool processing the query
worker_id — identifier of the worker processing the query
agent_id — identifier of the agent (host for the workers) processing the query
session_id — session identifier
other

Table `system.users`

Users metadata.

id — user identifier
name — user name
default_worker_pool — user’s default worker pool
auth_method — user authorisation type
query_timeout — timeout for user queries
spill_size — spill size (the amount of space on disc to save intermediate query results) for the user
other

Table `system.worker_pools`

Metadata of worker pools.

id — pool id
name — pool name
worker_size_id — pool size label
max_worker_count — maximum number of calculators for the pool
worker_idle_ttl_seconds — the idle time of calculators for the pool
scaling_strategy_id — scaling strategy for the pool

Usage examples

Let’s display all queries made by user tengri_user between December 21 and 23, 2025 with their duration, start time, session ID, and status:

SELECT
    query,
    duration_ms,
    started_at,
    session_id,
    status
FROM system.query_log
WHERE username = 'tengri_user'
    AND started_at BETWEEN '2025-12-21' AND '2025-12-23'

+-------------------+-------------+----------------------------+-----------------------------------------------------+---------+
| query             | duration_ms | started_at                 | session_id                                          | status  |
+-------------------+-------------+----------------------------+-----------------------------------------------------+---------+
| select * from ... | 2526        | 2026-04-13T16:21:31.686087 | f77b9a65-588d-46de-bdcb-07d1cf1f3ba1@localhost:5433 | success |
+-------------------+-------------+----------------------------+-----------------------------------------------------+---------+
| ...               | ...         | ...                        | ...                                                 | ...     |
+-------------------+-------------+----------------------------+-----------------------------------------------------+---------+

Let’s output information about all computational pools of size S:

SELECT * FROM system.worker_pools
WHERE worker_size_id = 'S'

+----+-----------+----------------+------------------+-------------------------+---------------------+
| id | name      | worker_size_id | max_worker_count | worker_idle_ttl_seconds | scaling_strategy_id |
+----+-----------+----------------+------------------+-------------------------+---------------------+
| 1  | default   | S              | 10               | 5                       | STD                 |
+----+-----------+----------------+------------------+-------------------------+---------------------+
| 5  | compute_s | S              | 10               | 5                       | STD                 |
+----+-----------+----------------+------------------+-------------------------+---------------------+

Getting current session ID

To get the current session ID, use the current_session() function.

SELECT current_session();

+-----------------------------------------------------+
| current_session                                     |
+-----------------------------------------------------+
| f77b9a65-588d-46de-bdcb-07d1cf1f3ba1@localhost:5433 |
+-----------------------------------------------------+

`SHOW` expressions

Metadata about various objects can also be retrieved using SHOW expressions:

SHOW TABLES — Table metadata.
SHOW COLUMNS — Column metadata.
SHOW USERS — User metadata.
SHOW WORKER POOLS — Compute pool metadata.
SHOW WORKER POOL — Metadata of the current compute pool.

PostgreSQL system tables

Metadata is also available via the system tables PostgreSQL in the pg_catalog schema:

pg_catalog.pg_namespace — Schema metadata.
pg_catalog.pg_class — Table metadata.
pg_catalog.pg_attribute — Column metadata.
pg_catalog.pg_type — Data type metadata.

Working with metadata

System tables

Table system.schemas

Table system.tables

Table system.query_log

Table system.users

Table system.worker_pools