---
title: "pg_clickhouse & chdb updates: Encoding, nesting, and types"
description: "pg_clickhouse v0.11.0 and the chdb extension v0.1.2 continue their focus on cross-database compatibility between ClickHouse and PostgreSQL with several enhancements derived from header-only C libraries. A new check_encoding server option provides error handlers for invalid byte sequences in text columns: fail, remove, replace, and truncate, with replace displaying the Unicode replacement character for UTF-8 databases. ClickHouse Interval types such as IntervalMillisecond are now imported as PostgreSQL interval columns, and expressions like start_at + duration are pushed down to ClickHouse. Unflattened Nested columns are mapped to two-dimensional text arrays by default, or to arrays of composite types when a structure is specified; parameterized JSON columns are mapped to jsonb with proper ORDER BY pushdown. Additional type mappings include Int128 and UInt256 to numeric, BFloat16 to float4, and spatial types; the deprecated clickhouse_raw_query function was removed, and PostgreSQL 13 support was dropped."
---

# pg\_clickhouse & chdb updates: Encoding, nesting, and types

[Clickhouse](https://yomu.fyi/company/clickhouse) · Sep 30, 2026

**Type:** Announcement

## Summary

pg\_clickhouse v0.11.0 and the chdb extension v0.1.2 continue their focus on cross-database compatibility between ClickHouse and PostgreSQL with several enhancements derived from header-only C libraries. A new check\_encoding server option provides error handlers for invalid byte sequences in text columns: fail, remove, replace, and truncate, with replace displaying the Unicode replacement character for UTF-8 databases. ClickHouse Interval types such as IntervalMillisecond are now imported as PostgreSQL interval columns, and expressions like start\_at + duration are pushed down to ClickHouse. Unflattened Nested columns are mapped to two-dimensional text arrays by default, or to arrays of composite types when a structure is specified; parameterized JSON columns are mapped to jsonb with proper ORDER BY pushdown. Additional type mappings include Int128 and UInt256 to numeric, BFloat16 to float4, and spatial types; the deprecated clickhouse\_raw\_query function was removed, and PostgreSQL 13 support was dropped.

## Context

The post announces new releases of pg\_clickhouse and the chdb extension, focusing on encoding, nesting, and type mapping improvements for cross-database compatibility.

## Approach / What changed

Added check\_encoding server option with four error handlers (fail, remove, replace, truncate); mapped ClickHouse Interval types to PostgreSQL interval with pushdown; mapped unflattened Nested to text\[\]\[\] or composite type arrays; mapped parameterized JSON to jsonb; updated type mappings for large integers, time, and spatial types; removed deprecated clickhouse\_raw\_query function; dropped PostgreSQL 13 support.

## Takeaways

- The check\_encoding option in pg\_clickhouse v0.11.0 provides four handlers (fail, remove, replace, truncate) for invalid byte sequences in text columns imported from ClickHouse.
- ClickHouse Interval types such as IntervalMillisecond are now imported as PostgreSQL interval columns, and expressions combining them with timestamps are pushed down to ClickHouse for execution.
- Unflattened Nested columns in ClickHouse are mapped to two-dimensional text arrays by default, or to arrays of composite types when a structure specification is provided.

## FAQ

### How can I handle invalid UTF-8 bytes in ClickHouse text columns?

Set the check\_encoding server option to 'replace' using ALTER SERVER; invalid bytes will be replaced with the Unicode replacement character for UTF-8 databases, or removed for other encodings. Alternative handlers are 'remove' and 'truncate'.

### Can I use ClickHouse Interval types in PostgreSQL?

Yes, they are automatically imported as PostgreSQL interval columns. Expressions like start\_at + duration are pushed down to ClickHouse, enabling efficient queries such as counting records before a certain date.

### How does pg\_clickhouse handle ClickHouse Nested types?

Unflattened Nested columns (with flatten\_nested=0) are mapped to two-dimensional text arrays (text\[\]\[\]) by default. You can also specify a structure to map them to arrays of composite types for better type fidelity.

**Tags:** [ClickHouse](https://yomu.fyi/topic/clickhouse), [Encoding](https://yomu.fyi/topic/encoding), [Postgres](https://yomu.fyi/topic/postgres)

- Source: [Clickhouse](https://clickhouse.com/blog/pg_clickhouse-chdb)
- Source URL: https://clickhouse.com/blog/pg_clickhouse-chdb
- Ingested by Yomu: 2026-09-30T18:00:08.558Z

[Read original post](https://clickhouse.com/blog/pg_clickhouse-chdb)