ClickHouse

QoreDB ships a native ClickHouse driver that talks to the server over HTTP (port 8123) or HTTPS (port 8443). The driver is wired into the standard DriverRegistry, so everything you expect from another engine — schema browser, query editor, results grid, exports, notebooks, DDL editor — works the same way against ClickHouse.

Quick connect

Pick the ClickHouse engine and enter the server address. The default port is 8123 (HTTP) or 8443 (HTTPS).

http://USER:PASSWORD@HOST:8123/DATABASE
https://USER:PASSWORD@HOST:8443/DATABASE

Managed ClickHouse Cloud clusters are exposed over HTTPS on 8443 with basic authentication.

Connection fields

Supported types

The driver maps 28 ClickHouse types to QoreDB's universal cell representation:

• Integers — Int8, Int16, Int32, Int64, Int128, and the matching UInt* family
• Floats and decimals — Float32, Float64, Decimal(P, S)
• Strings — String, FixedString(N)
• Dates and times — Date, Date32, DateTime, DateTime64(precision, timezone)
• Booleans, UUIDs, IP addresses — Bool, UUID, IPv4, IPv6
• Enums — Enum8, Enum16
• Composite types — Array(T), Tuple(T1, T2, …), Map(K, V)

Nullable(T) wrappers are transparent. Unknown types are surfaced as text rather than failing the query, so a result set with an exotic type still renders.

Query safety

ClickHouse statements are classified by an AST-aware analyzer with a four-level model — Read, Mutation, Dangerous, Unknown — that matches QoreDB's universal safety net:

• SELECT, WITH … SELECT, EXPLAIN, DESCRIBE, SHOW are Read.
• INSERT, ALTER … UPDATE/DELETE, CREATE, DROP, RENAME, TRUNCATE are Mutation.
• OPTIMIZE … FINAL, KILL QUERY, every SYSTEM … operation is refused outright as Dangerous. ClickHouse's SYSTEM commands (cache flushes, replica restarts, etc.) are powerful enough to disrupt a live cluster, so they require a manual override even in dev.

Read-only mode and environment guards apply the same way as on PostgreSQL or MySQL.

Cancelling a query

Long-running queries are cancelled via KILL QUERY WHERE query_id = <id>. ClickHouse treats this as best-effort: the server marks the query for cancellation and returns once the running fragment notices, which can take a moment for heavy aggregations.

DDL editor

The visual DDL editor supports ClickHouse with the dialect's specifics:

• Identifier quoting with backticks (`name`).
• CHECK constraints in CREATE TABLE.
• Indexes with INDEX name expr TYPE bloom_filter|minmax|set(...) GRANULARITY n.
• Engine families are not auto-selected; the generated DDL preserves the engine you typed.

ALTER TABLE coverage is currently limited to the MergeTree-family subset (add/drop column, modify column, add/drop index, attach/detach partition). Distributed table alterations and ON CLUSTER are not surfaced in the v1 editor — write them in the SQL editor for now.

Common issues

Where to go next

• Driver limitations for the per-engine quirks
• SQL safety validation for the universal safety net
• Querying: editor and autocomplete for the SQL editor