Documentation de référence pour pg_clickhouse

docker run --name pg_clickhouse -e POSTGRES_PASSWORD=my_pass \
       -d ghcr.io/clickhouse/pg_clickhouse:18
docker exec -it pg_clickhouse psql -U postgres

CREATE EXTENSION pg_clickhouse;
CREATE SERVER taxi_srv FOREIGN DATA WRAPPER clickhouse_fdw
       OPTIONS(driver 'binary', host 'localhost', dbname 'taxi');
CREATE USER MAPPING FOR CURRENT_USER SERVER taxi_srv
       OPTIONS (user 'default');
CREATE SCHEMA taxi;
IMPORT FOREIGN SCHEMA taxi FROM SERVER taxi_srv INTO taxi;

CREATE EXTENSION pg_clickhouse;

CREATE SCHEMA ch;
CREATE EXTENSION pg_clickhouse WITH SCHEMA ch;

DROP EXTENSION pg_clickhouse;

DROP EXTENSION pg_clickhouse CASCADE;

CREATE SERVER taxi_srv FOREIGN DATA WRAPPER clickhouse_fdw
       OPTIONS(driver 'binary', host 'localhost', dbname 'taxi');

ALTER SERVER taxi_srv OPTIONS (SET driver 'http');

DROP SERVER taxi_srv;

DROP SERVER taxi_srv CASCADE;

CREATE USER MAPPING FOR CURRENT_USER SERVER taxi_srv
       OPTIONS (user 'demo');

ALTER USER MAPPING FOR CURRENT_USER SERVER taxi_srv
       OPTIONS (SET user 'default');

DROP USER MAPPING FOR CURRENT_USER SERVER taxi_srv;

CREATE SCHEMA taxi;
IMPORT FOREIGN SCHEMA demo FROM SERVER taxi_srv INTO taxi;

IMPORT FOREIGN SCHEMA demo LIMIT TO (trips) FROM SERVER taxi_srv INTO taxi;

IMPORT FOREIGN SCHEMA demo EXCEPT (users) FROM SERVER taxi_srv INTO taxi;

CREATE FOREIGN TABLE acts (
    user_id    bigint NOT NULL,
    page_views int,
    duration   smallint,
    sign       smallint
) SERVER taxi_srv OPTIONS(
    table_name 'acts'
    engine 'CollapsingMergeTree(sign)'
);

CREATE TABLE hits (
    user_id UInt64,
    hits    AggregateFunction(count)
) ENGINE = AggregatingMergeTree() ORDER BY user_id;

CREATE FOREIGN TABLE hits (
    user_id bigint NOT NULL,
    hits    bigint NOT NULL OPTIONS(AggregateFunction 'count')
) SERVER clickhouse_srv;

try=# EXPLAIN (VERBOSE, COSTS OFF)
       SELECT user_id, count(hits) FROM hits GROUP BY user_id;
                                 QUERY PLAN
----------------------------------------------------------------------------
 Foreign Scan
   Output: user_id, (count(*))
   Relations: Aggregate on (hits)
   Remote SQL: SELECT user_id, count(*) FROM "default".hits GROUP BY user_id
(4 rows)

try=# SELECT user_id, count(hits) FROM hits GROUP BY user_id;
 user_id | count
---------+-------
       1 |     1
(1 row)

CREATE FOREIGN TABLE hits (
    user_id bigint NOT NULL,
    hits    bigint OPTIONS(AggregateFunction 'count')
) SERVER clickhouse_srv;

try=# EXPLAIN (VERBOSE, COSTS OFF)
       SELECT user_id, count(hits) FROM hits GROUP BY user_id;
                                     QUERY PLAN
------------------------------------------------------------------------------------
 Foreign Scan
   Output: user_id, (count(hits))
   Relations: Aggregate on (hits)
   Remote SQL: SELECT user_id, countMerge(hits) FROM "default".hits GROUP BY user_id
(4 rows)

try=# SELECT user_id, count(hits) FROM hits GROUP BY user_id;
 user_id | count
---------+-------
       1 |  1000
(1 row)

ALTER FOREIGN TABLE hits ALTER COLUMN hits DROP NOT NULL;

ALTER TABLE table ALTER COLUMN b OPTIONS (SET AggregateFunction 'count');

DROP FOREIGN TABLE acts;

DROP FOREIGN TABLE acts CASCADE;

CREATE TABLE logs (
    req_id    Int64 NOT NULL,
    start_at   DateTime64(6, 'UTC') NOT NULL,
    duration  Int32 NOT NULL,
    resource  Text  NOT NULL,
    method    Enum8('GET' = 1, 'HEAD', 'POST', 'PUT', 'DELETE', 'CONNECT', 'OPTIONS', 'TRACE', 'PATCH', 'QUERY') NOT NULL,
    node_id   Int64 NOT NULL,
    response  Int32 NOT NULL
) ENGINE = MergeTree
  ORDER BY start_at;

CREATE TABLE nodes (
    node_id Int64 NOT NULL,
    name    Text  NOT NULL,
    region  Text  NOT NULL,
    arch    Text  NOT NULL,
    os      Text  NOT NULL
) ENGINE = MergeTree
  PRIMARY KEY node_id;

try=# EXPLAIN (VERBOSE)
       SELECT resource, avg(duration) AS average_duration
         FROM logs
        GROUP BY resource;
                                     QUERY PLAN
------------------------------------------------------------------------------------
 Foreign Scan  (cost=1.00..5.10 rows=1000 width=64)
   Output: resource, (avg(duration))
   Relations: Aggregate on (logs)
   Remote SQL: SELECT resource, avg(duration) FROM "default".logs GROUP BY resource
(4 rows)

try=# SELECT start_at, duration, resource FROM logs WHERE req_id = 4117909262;
          start_at          | duration |    resource
----------------------------+----------+----------------
 2025-12-05 15:07:32.944188 |      175 | /widgets/totem
(1 row)

try=# EXPLAIN (VERBOSE, COSTS OFF)
       SELECT start_at, duration, resource FROM logs WHERE req_id = 4117909262;
                                             QUERY PLAN
-----------------------------------------------------------------------------------------------------
 Foreign Scan on public.logs
   Output: start_at, duration, resource
   Remote SQL: SELECT start_at, duration, resource FROM "default".logs WHERE ((req_id = 4117909262))
(3 rows)

try=# EXPLAIN (ANALYZE, VERBOSE)
       SELECT name, count(*), round(avg(duration))
         FROM logs
         LEFT JOIN nodes on logs.node_id = nodes.node_id
        GROUP BY name;
                                                                                  QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Foreign Scan  (cost=1.00..5.10 rows=1000 width=72) (actual time=3.201..3.221 rows=8.00 loops=1)
   Output: nodes.name, (count(*)), (round(avg(logs.duration), 0))
   Relations: Aggregate on ((logs) LEFT JOIN (nodes))
   Remote SQL: SELECT r2.name, count(*), round(avg(r1.duration), 0) FROM  "default".logs r1 ALL LEFT JOIN "default".nodes r2 ON (((r1.node_id = r2.node_id))) GROUP BY r2.name
   FDW Time: 0.086 ms
 Planning Time: 0.335 ms
 Execution Time: 3.261 ms
(7 rows)

try=# CREATE TABLE local_nodes AS SELECT * FROM nodes;
SELECT 8

try=# EXPLAIN (ANALYZE, VERBOSE)
       SELECT name, count(*), round(avg(duration))
         FROM logs
         LEFT JOIN local_nodes on logs.node_id = local_nodes.node_id
        GROUP BY name;
                                                             QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------
 HashAggregate  (cost=147.65..150.65 rows=200 width=72) (actual time=6.215..6.235 rows=8.00 loops=1)
   Output: local_nodes.name, count(*), round(avg(logs.duration), 0)
   Group Key: local_nodes.name
   Batches: 1  Memory Usage: 32kB
   Buffers: shared hit=1
   ->  Hash Left Join  (cost=31.02..129.28 rows=2450 width=36) (actual time=2.202..5.125 rows=1000.00 loops=1)
         Output: local_nodes.name, logs.duration
         Hash Cond: (logs.node_id = local_nodes.node_id)
         Buffers: shared hit=1
         ->  Foreign Scan on public.logs  (cost=10.00..20.00 rows=1000 width=12) (actual time=2.089..3.779 rows=1000.00 loops=1)
               Output: logs.req_id, logs.start_at, logs.duration, logs.resource, logs.method, logs.node_id, logs.response
               Remote SQL: SELECT duration, node_id FROM "default".logs
               FDW Time: 1.447 ms
         ->  Hash  (cost=14.90..14.90 rows=490 width=40) (actual time=0.090..0.091 rows=8.00 loops=1)
               Output: local_nodes.name, local_nodes.node_id
               Buckets: 1024  Batches: 1  Memory Usage: 9kB
               Buffers: shared hit=1
               ->  Seq Scan on public.local_nodes  (cost=0.00..14.90 rows=490 width=40) (actual time=0.069..0.073 rows=8.00 loops=1)
                     Output: local_nodes.name, local_nodes.node_id
                     Buffers: shared hit=1
 Planning:
   Buffers: shared hit=14
 Planning Time: 0.551 ms
 Execution Time: 6.589 ms

try=# EXPLAIN (ANALYZE, VERBOSE)
       WITH remote AS (
           SELECT node_id, count(*), round(avg(duration))
             FROM logs
            GROUP BY node_id
       )
       SELECT name, remote.count, remote.round
         FROM remote
         JOIN local_nodes
           ON remote.node_id = local_nodes.node_id
        ORDER BY name;
                                                          QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=65.68..66.91 rows=490 width=72) (actual time=4.480..4.484 rows=8.00 loops=1)
   Output: local_nodes.name, remote.count, remote.round
   Sort Key: local_nodes.name
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=4
   ->  Hash Join  (cost=27.60..43.79 rows=490 width=72) (actual time=4.406..4.422 rows=8.00 loops=1)
         Output: local_nodes.name, remote.count, remote.round
         Inner Unique: true
         Hash Cond: (local_nodes.node_id = remote.node_id)
         Buffers: shared hit=1
         ->  Seq Scan on public.local_nodes  (cost=0.00..14.90 rows=490 width=40) (actual time=0.010..0.016 rows=8.00 loops=1)
               Output: local_nodes.node_id, local_nodes.name, local_nodes.region, local_nodes.arch, local_nodes.os
               Buffers: shared hit=1
         ->  Hash  (cost=15.10..15.10 rows=1000 width=48) (actual time=4.379..4.381 rows=8.00 loops=1)
               Output: remote.count, remote.round, remote.node_id
               Buckets: 1024  Batches: 1  Memory Usage: 9kB
               ->  Subquery Scan on remote  (cost=1.00..15.10 rows=1000 width=48) (actual time=4.337..4.360 rows=8.00 loops=1)
                     Output: remote.count, remote.round, remote.node_id
                     ->  Foreign Scan  (cost=1.00..5.10 rows=1000 width=48) (actual time=4.330..4.349 rows=8.00 loops=1)
                           Output: logs.node_id, (count(*)), (round(avg(logs.duration), 0))
                           Relations: Aggregate on (logs)
                           Remote SQL: SELECT node_id, count(*), round(avg(duration), 0) FROM "default".logs GROUP BY node_id
                           FDW Time: 0.055 ms
 Planning:
   Buffers: shared hit=5
 Planning Time: 0.319 ms
 Execution Time: 4.562 ms

CREATE TABLE events (id int, ts date, val int, amt float8)
    PARTITION BY RANGE (ts);

-- 2023 data lives on ClickHouse
CREATE FOREIGN TABLE events_2023 PARTITION OF events
    FOR VALUES FROM ('2023-01-01') TO ('2024-01-01')
    SERVER ch_srv OPTIONS (table_name 'events');

-- 2024 data stays local
CREATE TABLE events_2024 PARTITION OF events
    FOR VALUES FROM ('2024-01-01') TO ('2025-01-01');

SET enable_partitionwise_aggregate = on;

try=# EXPLAIN (VERBOSE, COSTS OFF)
       SELECT count(*), sum(val), min(ts), max(ts) FROM events;
                                                       QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------
 Finalize Aggregate
   Output: count(*), sum(events.val), min(events.ts), max(events.ts)
   ->  Append
         ->  Foreign Scan
               Output: (PARTIAL count(*)), (PARTIAL sum(events.val)), (PARTIAL min(events.ts)), (PARTIAL max(events.ts))
               Relations: Aggregate on (events_2023 events)
               Remote SQL: SELECT count(*), sum(val), min(ts), max(ts) FROM "default".events
         ->  Partial Aggregate
               Output: PARTIAL count(*), PARTIAL sum(events_1.val), PARTIAL min(events_1.ts), PARTIAL max(events_1.ts)
               ->  Seq Scan on public.events_2024 events_1
                     Output: events_1.val, events_1.ts

try=# PREPARE avg_durations_between_dates(date, date) AS
       SELECT date(start_at), round(avg(duration)) AS average_duration
         FROM logs
        WHERE date(start_at) BETWEEN $1 AND $2
        GROUP BY date(start_at)
        ORDER BY date(start_at);
PREPARE

try=# EXECUTE avg_durations_between_dates('2025-12-09', '2025-12-13');
    date    | average_duration
------------+------------------
 2025-12-09 |              190
 2025-12-10 |              194
 2025-12-11 |              197
 2025-12-12 |              190
 2025-12-13 |              195
(5 rows)

try=# EXPLAIN (VERBOSE) EXECUTE avg_durations_between_dates('2025-12-09', '2025-12-13');
                                                                                                            QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Foreign Scan  (cost=1.00..5.10 rows=1000 width=36)
   Output: (date(start_at)), (round(avg(duration), 0))
   Relations: Aggregate on (logs)
   Remote SQL: SELECT date(start_at), round(avg(duration), 0) FROM "default".logs WHERE ((date(start_at) >= '2025-12-09')) AND ((date(start_at) <= '2025-12-13')) GROUP BY (date(start_at)) ORDER BY date(start_at) ASC NULLS LAST
(4 rows)

                                                                                                         QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Foreign Scan  (cost=1.00..5.10 rows=1000 width=36)
   Output: (date(start_at)), (round(avg(duration), 0))
   Relations: Aggregate on (logs)
   Remote SQL: SELECT date(start_at), round(avg(duration), 0) FROM "default".logs WHERE ((date(start_at) >= {p1:Date})) AND ((date(start_at) <= {p2:Date})) GROUP BY (date(start_at)) ORDER BY date(start_at) ASC NULLS LAST
(4 rows)

try=# DEALLOCATE avg_durations_between_dates;
DEALLOCATE

try=# INSERT INTO nodes(node_id, name, region, arch, os)
VALUES (9,  'Augustin Gamarra', 'us-west-2', 'amd64', 'Linux')
     , (10, 'Cerisier', 'us-east-2', 'amd64', 'Linux')
     , (11, 'Dewalt', 'use-central-1', 'arm64', 'macOS')
;
INSERT 0 3

try=# COPY logs FROM stdin CSV;
4285871863,2025-12-05 11:13:58.360760,206,/widgets,POST,8,401
4020882978,2025-12-05 11:33:48.248450,199,/users/1321945,HEAD,3,200
3231273177,2025-12-05 12:20:42.158575,220,/search,GET,2,201
\.
>> COPY 3

try=# LOAD 'pg_clickhouse';
LOAD

SET pg_clickhouse.session_settings = 'join_use_nulls 1, final 1';

join_use_nulls 1, group_by_use_nulls 1, final 1, transform_null_in 0

SET pg_clickhouse.session_settings = '';

SET pg_clickhouse.session_settings = 'join_algorithm grace_hash\,hash';

SET pg_clickhouse.session_settings = $$join_algorithm 'grace_hash,hash'$$;

SET pg_clickhouse.session_settings TO $$
    connect_timeout 2,
    count_distinct_implementation uniq,
    final 1,
    group_by_use_nulls 1,
    join_algorithm 'prefer_partial_merge',
    join_use_nulls 1,
    log_queries_min_type QUERY_FINISH,
    max_block_size 32768,
    max_execution_time 45,
    max_result_rows 1024,
    metrics_perf_events_list 'this,that',
    network_compression_method ZSTD,
    poll_interval 5,
    totals_mode after_having_auto
$$;

SET pg_clickhouse.pushdown_regex = 'false';

try=# ALTER ROLE CURRENT_USER SET session_preload_libraries = pg_clickhouse;
ALTER ROLE

try=# ALTER ROLE CURRENT_USER SET pg_clickhouse.session_settings = 'final 1';
ALTER ROLE

try=# ALTER ROLE CURRENT_USER RESET session_preload_libraries;
ALTER ROLE

try=# ALTER ROLE CURRENT_USER RESET pg_clickhouse.session_settings;
ALTER ROLE

session_preload_libraries = pg_clickhouse

shared_preload_libraries = pg_clickhouse

-- Create ClickHouse table with String columns.
CALL clickhouse_perform('ch_srv', $$
    CREATE TABLE bytes (
        c1 Int8, c2 String, c3 String
    ) ENGINE = MergeTree ORDER BY (c1);
$$);

-- Create foreign table with BYTEA columns.
CREATE FOREIGN TABLE bytes (
    c1 int,
    c2 BYTEA,
    c3 BYTEA
) SERVER ch_srv OPTIONS( table_name 'bytes' );

-- Insert binary data into the foreign table.
INSERT INTO bytes
SELECT n, sha224(bytea('val'||n)), decode(md5('int'||n), 'hex')
  FROM generate_series(1, 4) n;

-- View the results.
SELECT * FROM bytes;

 c1 |                             c2                             |                 c3
----+------------------------------------------------------------+------------------------------------
  1 | \x1bf7f0cc821d31178616a55a8e0c52677735397cdde6f4153a9fd3d7 | \xae3b28cde02542f81acce8783245430d
  2 | \x5f6e9e12cd8592712e638016f4b1a2e73230ee40db498c0f0b1dc841 | \x23e7c6cacb8383f878ad093b0027d72b
  3 | \x53ac2c1fa83c8f64603fe9568d883331007d6281de330a4b5e728f9e | \x7e969132fc656148b97b6a2ee8bc83c1
  4 | \x4e3c2e4cb7542a45173a8dac939ddc4bc75202e342ebc769b0f5da2f | \x8ef30f44c65480d12b650ab6b2b04245
(4 rows)

-- Create foreign table with TEXT columns.
CREATE FOREIGN TABLE texts (
    c1 int,
    c2 TEXT,
    c3 TEXT
) SERVER ch_srv OPTIONS( table_name 'bytes' );

-- Encode binary data as hex.
SELECT c1, encode(c2::bytea, 'hex'), encode(c3::bytea, 'hex') FROM texts ORDER BY c1;

ERROR:  invalid byte sequence for encoding "UTF8": 0xf7 0xf0 0xcc 0x82

-- Insert via text columns:
TRUNCATE texts;
INSERT INTO texts
SELECT n, sha224(bytea('val'||n)), decode(md5('int'||n), 'hex')
  FROM generate_series(1, 4) n;

-- View the data.
SELECT c1, encode(c2::bytea, 'hex'), encode(c3::bytea, 'hex') FROM texts ORDER BY c1;

 c1 |                          encode                          |              encode
----+----------------------------------------------------------+----------------------------------
  1 | 1bf7f0cc821d31178616a55a8e0c52677735397cdde6f4153a9fd3d7 | ae3b28cde02542f81acce8783245430d
  2 | 5f6e9e12cd8592712e638016f4b1a2e73230ee40db498c0f0b1dc841 | 23e7c6cacb8383f878ad093b0027d72b
  3 | 53ac2c1fa83c8f64603fe9568d883331007d6281de330a4b5e728f9e | 7e969132fc656148b97b6a2ee8bc83c1
  4 | 4e3c2e4cb7542a45173a8dac939ddc4bc75202e342ebc769b0f5da2f | 8ef30f44c65480d12b650ab6b2b04245
(4 rows)

# SELECT * FROM bytes;
 c1 |                                                           c2                                                           |                                   c3
----+------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------
  1 | \x5c783162663766306363383231643331313738363136613535613865306335323637373733353339376364646536663431353361396664336437 | \x5c786165336232386364653032353432663831616363653837383332343534333064
  2 | \x5c783566366539653132636438353932373132653633383031366634623161326537333233306565343064623439386330663062316463383431 | \x5c783233653763366361636238333833663837386164303933623030323764373262
  3 | \x5c783533616332633166613833633866363436303366653935363864383833333331303037643632383164653333306134623565373238663965 | \x5c783765393639313332666336353631343862393762366132656538626338336331
  4 | \x5c783465336332653463623735343261343531373361386461633933396464633462633735323032653334326562633736396230663564613266 | \x5c783865663330663434633635343830643132623635306162366232623034323435
(4 rows)

SELECT * FROM things where tags[1] = 'foo';
SELECT * FROM things where pairs[1][2] = 'bar';

SELECT id, vals FROM t1 WHERE vals[1:2] = ARRAY[10,20];
SELECT id, vals FROM t1 WHERE vals[1:2][2] = 20; -- currently fails

-- Create ClickHouse table with Map column.
CALL clickhouse_perform('ch_srv', $$
    CREATE TABLE maps (
        c1 Int32,
        c2 Map(String, Int64)
    ) ENGINE = MergeTree ORDER BY (c1);
$$);

-- Import text[][] column, then insert two pairs.
IMPORT FOREIGN SCHEMA ch LIMIT TO (maps) FROM SERVER ch_srv INTO public;
INSERT INTO maps VALUES (1, ARRAY[['a', '1'], ['b', '2']]);

try=# SELECT * FROM maps;
 c1 |      c2
----+---------------
  1 | {{a,1},{b,2}}
(1 row)

-- Create ClickHouse table with flattened Nested column.
CALL clickhouse_perform('ch_srv', $$
    CREATE TABLE ch.nests (
        c1 Int32,
        c2 Nested(id Int64, name String)
    ) ENGINE = MergeTree ORDER BY (c1)
$$);

-- Import text[][] column, then insert two pairs.
IMPORT FOREIGN SCHEMA ch LIMIT TO (nests) FROM SERVER ch_srv INTO public;

                   Foreign table "public.nests"
 Column  |   Type   | Collation | Nullable | Default | FDW options
---------+----------+-----------+----------+---------+-------------
 c1      | integer  |           | not null |         |
 c2.id   | bigint[] |           | not null |         |
 c2.name | text[]   |           | not null |         |

SELECT ci, "c2.id" FROM nests;

SELECT * FROM nests
 WHERE "c2.id[2]" = '2' OR '12' = ANY("c2.id");

-- Create ClickHouse table with unflattened Nested column.
CALL clickhouse_perform('ch_srv', $$
    CREATE TABLE nests (
        c1 Int32,
        c2 Nested(id Int64, name String)
    ) ENGINE = MergeTree ORDER BY (c1) SETTINGS flatten_nested=0
$$);

-- Import text[][] column, then insert two pairs.
IMPORT FOREIGN SCHEMA ch LIMIT TO (nests) FROM SERVER ch_srv INTO public;

                  Foreign table "public.nests"
 Column |  Type   | Collation | Nullable | Default | FDW options
--------+---------+-----------+----------+---------+-------------
 c1     | integer |           | not null |         |
 c2     | text[]  |           | not null |         |

INSERT INTO nests
VALUES (1, ARRAY[['42', 'Arthur'], ['99', 'Barbara']]);

SELECT * FROM nests WHERE c2[1][1] = '42`
ERROR:  pg_clickhouse: DB::Exception: First argument for function 'arrayElement' must be array, got 'Tuple(serial UInt32, order_id String)' instead

SELECT * FROM nests WHERE c2[1].id = 42;

CALL clickhouse_perform('ch_srv', $$
    CREATE TABLE events (
      id     UInt32,
      status Enum8('new' = 1, 'done' = 2),
      point  Tuple(Int32, Int32),
      labels Map(String, Int64),
      items  Nested(id Int32, name String)
    ) ORDER BY id SETTINGS flatten_nested = 0
$$);

CALL clickhouse_perform('ch_srv', $$
    INSERT INTO events
    VALUES(1, 'new', tuple(3, 4), {'k1': 5, 'k2': 6}, [tuple(100, 'xx')])
$$);

CREATE TYPE event_status AS ENUM ('new', 'done');
CREATE TYPE event_point AS (x integer, y integer);
CREATE TYPE event_label AS (key text, value bigint);
CREATE TYPE event_item AS (id integer, name text);

CREATE FOREIGN TABLE events (
    id     bigint,
    status event_status,
    point  event_point,
    labels event_label[],
    items  event_item[]
) SERVER clickhouse_srv;

SELECT * FROM events ORDER BY id;
 id | status | point |       labels        |          items
----+--------+-------+---------------------+-------------------------
  1 | new    | (3,4) | {"(k1,5)","(k2,6)"} | {"(100,xx)","(101,yy)"}
(1 row)

SELECT (point).x,       (point).y,
       (labels[1]).key, (labels[1]).value,
       (items[1]).id,   (items[1]).name
  FROM events ORDER BY id;
 x | y | key | value | id  | name
---+---+-----+-------+-----+------
 3 | 4 | k1  |     5 | 100 | xx

SELECT * FROM events WHERE items[1].name = 'xx';

SELECT clickhouse_server_version('taxi_srv');

 clickhouse_server_version
---------------------------
 25.8.1
(1 row)

SELECT * FROM clickhouse_query(
    'server',
    'SELECT id, name, salary FROM remote_table WHERE salary > 50000'
) AS ch(id int, name text, salary numeric);

GRANT EXECUTE ON FUNCTION clickhouse_query(text, text) TO ch_admin;

CALL clickhouse_perform(
    'server',
    'CREATE TABLE remote_table (id Int32) ENGINE = MergeTree ORDER BY id'
);

GRANT EXECUTE ON PROCEDURE clickhouse_perform(text, text) TO ch_admin;

SELECT percentile_cont(0.25) WITHIN GROUP (ORDER BY a) FROM t1;

SELECT quantile(0.25)(a) FROM t1;