Improve error messages for publication/subscription failures

Extract full PostgreSQL error details (code, message, detail, hint) instead
of showing unhelpful "db error" messages. Helps users diagnose permission
issues, missing tables, and other sync failures.

Taariq Lewis, SerenAI, Paloma, and Volume at https://serendb.com

Author: taariq

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes to this project will be documented in this file.
 
+## [7.2.2] - 2026-01-05
+
+### Improved
+
+- **Better error messages for publication/subscription failures**: Publication and subscription creation errors now extract the full PostgreSQL error including error code, message, detail, and hint. Previously, errors would show unhelpful "db error" messages instead of the actual PostgreSQL error (e.g., missing privileges, table not found).
+
 ## [7.2.1] - 2026-01-05
 
 ### Fixed

Cargo.lock

@@ -7,7 +7,7 @@ members = [
 
 [package]
 name = "database-replicator"
-version = "7.2.1"
+version = "7.2.2"
 edition = "2021"
 license = "Apache-2.0"
 description = "Universal database-to-PostgreSQL replication CLI. Supports PostgreSQL, SQLite, MongoDB, and MySQL."

Cargo.toml

@@ -132,6 +132,37 @@ pub async fn create_publication(
     execute_publication_query(client, publication_name, &query).await
 }
 
+/// Extract detailed error message from tokio-postgres error
+fn extract_pg_error_details(e: &tokio_postgres::Error) -> String {
+    let error_msg = e.to_string();
+
+    if let Some(db_error) = e.as_db_error() {
+        // PostgreSQL returned a specific error - extract all details
+        let mut details = format!(
+            "PostgreSQL error {}: {}",
+            db_error.code().code(),
+            db_error.message()
+        );
+        if let Some(detail) = db_error.detail() {
+            details.push_str(&format!("\nDetail: {}", detail));
+        }
+        if let Some(hint) = db_error.hint() {
+            details.push_str(&format!("\nHint: {}", hint));
+        }
+        details
+    } else if let Some(source) = std::error::Error::source(e) {
+        // Check for underlying IO or TLS errors
+        format!("{} (caused by: {})", error_msg, source)
+    } else {
+        // Use debug format for more information when to_string() is unhelpful
+        if error_msg == "db error" || error_msg.len() < 20 {
+            format!("{:?}", e)
+        } else {
+            error_msg
+        }
+    }
+}
+
 async fn execute_publication_query(
     client: &Client,
     publication_name: &str,
@@ -143,7 +174,7 @@ async fn execute_publication_query(
             Ok(())
         }
         Err(e) => {
-            let err_str = e.to_string();
+            let err_str = extract_pg_error_details(&e);
             // Publication might already exist - that's okay
             if err_str.contains("already exists") {
                 tracing::info!("✓ Publication '{}' already exists", publication_name);

src/replication/publication.rs

@@ -5,6 +5,37 @@ use anyhow::{Context, Result};
 use std::time::Duration;
 use tokio_postgres::Client;
 
+/// Extract detailed error message from tokio-postgres error
+fn extract_pg_error_details(e: &tokio_postgres::Error) -> String {
+    let error_msg = e.to_string();
+
+    if let Some(db_error) = e.as_db_error() {
+        // PostgreSQL returned a specific error - extract all details
+        let mut details = format!(
+            "PostgreSQL error {}: {}",
+            db_error.code().code(),
+            db_error.message()
+        );
+        if let Some(detail) = db_error.detail() {
+            details.push_str(&format!("\nDetail: {}", detail));
+        }
+        if let Some(hint) = db_error.hint() {
+            details.push_str(&format!("\nHint: {}", hint));
+        }
+        details
+    } else if let Some(source) = std::error::Error::source(e) {
+        // Check for underlying IO or TLS errors
+        format!("{} (caused by: {})", error_msg, source)
+    } else {
+        // Use debug format for more information when to_string() is unhelpful
+        if error_msg == "db error" || error_msg.len() < 20 {
+            format!("{:?}", e)
+        } else {
+            error_msg
+        }
+    }
+}
+
 /// Create a subscription to a publication on the source database
 pub async fn create_subscription(
     client: &Client,
@@ -66,7 +97,7 @@ pub async fn create_subscription(
             Ok(())
         }
         Err(e) => {
-            let err_str = e.to_string();
+            let err_str = extract_pg_error_details(&e);
             // Subscription might already exist - that's okay
             if err_str.contains("already exists") {
                 tracing::info!("✓ Subscription '{}' already exists", subscription_name);