Add cache pressure summary and include failing query in error logs

Log a one-line summary after each cache-pressure pass (files/bytes
added, evicted, and skipped by reason) so we can see why the cache
stayed full or churned. Append the first 500 chars of the failing
query to pgduck_server parse/bind/execute WARNING lines so a stray
error is debuggable without replaying the session.

Signed-off-by: Marco Slot <marco.slot@snowflake.com>

Author: sfc-gh-mslot

duckdb_pglake/src/fs/file_cache_manager.cpp

@@ -702,6 +702,43 @@ FileCacheManager::ManageCache(ClientContext &context, int64_t maxCacheSize)
 		}
 	}
 
+	int64_t added = 0, addedBytes = 0;
+	int64_t removed = 0, removedBytes = 0;
+	int64_t skippedTooLarge = 0, skippedTooOld = 0;
+	int64_t skippedConcurrent = 0, addFailed = 0;
+
+	for (const CacheAction &a : actions)
+	{
+		switch (a.action)
+		{
+			case ADDED:             added++; addedBytes += a.fileSize; break;
+			case REMOVED:           removed++; removedBytes += a.fileSize; break;
+			case SKIPPED_TOO_LARGE: skippedTooLarge++; break;
+			case SKIPPED_TOO_OLD:   skippedTooOld++; break;
+			case SKIPPED_CONCURRENT_MODIFY: skippedConcurrent++; break;
+			case ADD_FAILED:        addFailed++; break;
+			default:                break;
+		}
+	}
+
+	if (added > 0 || removed > 0 || skippedTooOld > 0 ||
+		skippedTooLarge > 0 || addFailed > 0)
+	{
+		PGDUCK_SERVER_LOG("cache pressure: added %" PRIu64 " files (%" PRIu64
+						  " bytes), evicted %" PRIu64 " files (%" PRIu64 " bytes), "
+						  "skipped %" PRIu64 " (too old), %" PRIu64 " (too large), "
+						  "%" PRIu64 " (concurrent), %" PRIu64 " (add failed); "
+						  "cache now %" PRIu64 "/%" PRIu64 " bytes",
+						  (uint64_t) added, (uint64_t) addedBytes,
+						  (uint64_t) removed, (uint64_t) removedBytes,
+						  (uint64_t) skippedTooOld,
+						  (uint64_t) skippedTooLarge,
+						  (uint64_t) skippedConcurrent,
+						  (uint64_t) addFailed,
+						  (uint64_t) totalCacheSize,
+						  (uint64_t) maxCacheSize);
+	}
+
 	return actions;
 }
 

pgduck_server/src/duckdb/duckdb.c

@@ -759,7 +759,8 @@ duckdb_session_run_command(DuckDBSession * duckSession, const char *queryString,
 		}
 		else
 		{
-			PGDUCK_SERVER_WARN("query on duckdb failed: %s", duckdbError);
+			PGDUCK_SERVER_WARN("query on duckdb failed: %s; query: %.500s",
+							   duckdbError, queryString);
 			status = DUCKDB_QUERY_ERROR;
 		}
 
@@ -931,7 +932,9 @@ duckdb_session_execute_prepared(DuckDBSession * duckSession,
 		}
 		else
 		{
-			PGDUCK_SERVER_WARN("could not execute prepared statement: %s", duckdbError);
+			PGDUCK_SERVER_WARN("could not execute prepared statement: %s; query: %.500s",
+							   duckdbError,
+							   duckSession->clientSession->pgSessionPreparedStmt.queryString);
 			status = DUCKDB_QUERY_ERROR;
 		}
 
@@ -1216,7 +1219,9 @@ process_and_send_data_chunks(DuckDBQueryResult * duckdb_query_result,
 				}
 				else
 				{
-					PGDUCK_SERVER_WARN("query on duckdb failed during execution: %s", duckdbError);
+					PGDUCK_SERVER_WARN("query on duckdb failed during execution: %s; query: %.500s",
+									   duckdbError,
+									   clientSession->pgSessionPreparedStmt.queryString);
 					status = DUCKDB_QUERY_ERROR;
 				}
 

pgduck_server/src/pgsession/pgsession.c

@@ -562,9 +562,10 @@ process_parse_message(PGSession * pgSession, StringInfo inputMessage)
 		/* we have to raise errors to the client */
 		int			sentErrorMsg = handle_pgsession_error_message(status, pgSession, errorMessage);
 
-		PGDUCK_SERVER_WARN("query from client %d failed during parse: %s",
+		PGDUCK_SERVER_WARN("query from client %d failed during parse: %s; query: %.500s",
 						   pgSession->pgClient->clientSocket,
-						   errorMessage);
+						   errorMessage,
+						   queryStringCopy);
 
 		/* free error message allocated by duckdb_session_prepare */
 		pfree(errorMessage);
@@ -706,9 +707,10 @@ process_bind_message(PGSession * pgSession, StringInfo inputMessage)
 		{
 			int			sentResult = handle_pgsession_error_message(bindResult, pgSession, errorMessage);
 
-			PGDUCK_SERVER_WARN("query from client %d failed during bind: %s",
+			PGDUCK_SERVER_WARN("query from client %d failed during bind: %s; query: %.500s",
 							   pgSession->pgClient->clientSocket,
-							   errorMessage);
+							   errorMessage,
+							   pgSession->pgSessionPreparedStmt.queryString);
 
 			/* free error message allocated by duckdb_session_bind_varchar */
 			pfree(errorMessage);