wip: add support for custom schema and default schema for cloudsync_init

- Allow schema-qualified inputs, e.g. cloudsync_init('public.users').
- Parse schema/table and propagate through query builders.
- Always generate fully-qualified table names ("schema"."table").
- Apply schema-aware filters in information_schema queries.
- Removes ambiguity regardless of search_path or duplicate table names across schemas.
- Note: payload compatibility requires cloudsync_changes.tbl to remain unqualified; PG apply should resolve schema via cloudsync_table_settings (not search_path) when applying payloads.

The unittest runs fine with this changes, but the merge tests fail. This code need to be fixed before being adopted

Author: andinux

src/cloudsync.c

@@ -82,6 +82,8 @@ int64_t  database_schema_version (cloudsync_context *data);
 uint64_t database_schema_hash (cloudsync_context *data);
 bool     database_check_schema_hash (cloudsync_context *data, uint64_t hash);
 int      database_update_schema_hash (cloudsync_context *data, uint64_t *hash);
+char    *database_current_schema (cloudsync_context *data);
+char    *database_default_schema (cloudsync_context *data);
 
 int database_begin_savepoint (cloudsync_context *data, const char *savepoint_name);
 int database_commit_savepoint (cloudsync_context *data, const char *savepoint_name);
@@ -143,6 +145,11 @@ char *sql_build_insert_pk_ignore (cloudsync_context *data, const char *table_nam
 char *sql_build_upsert_pk_and_col (cloudsync_context *data, const char *table_name, const char *colname);
 char *sql_build_select_cols_by_pk (cloudsync_context *data, const char *table_name, const char *colname);
 char *sql_build_rekey_pk_and_reset_version_except_col (cloudsync_context *data, const char *table_name, const char *except_col);
+char *sql_build_tableinfo_list_nonpk_name_cid (cloudsync_context *data, const char *table_name, const char *schema);
+char *sql_build_delete_cols_not_in_schema_or_pkcol (cloudsync_context *data, const char *table_name, const char *schema, const char *tombstone);
+char *sql_build_pk_qualified_collist (cloudsync_context *data, const char *table_name, const char *schema);
+char *sql_build_pk_collist (cloudsync_context *data, const char *table_name, const char *schema);
+char *sql_build_pk_decode_selectlist (cloudsync_context *data, const char *table_name, const char *schema);
 
 // USED ONLY by SQLite Cloud to implement RLS
 typedef struct cloudsync_pk_decode_bind_context cloudsync_pk_decode_bind_context;

src/database.h

@@ -7,6 +7,7 @@
 
 #include <stdlib.h>
 #include <inttypes.h>
+#include <string.h>
 
 #include "sql.h"
 #include "utils.h"
@@ -358,8 +359,28 @@ int dbutils_settings_table_load_callback (void *xdata, int ncols, char **values,
         if (strcmp(key, "algo")!=0) continue;
 
         table_algo algo = cloudsync_algo_from_name(value);
-        if (database_create_triggers(data, table_name, algo) != DBRES_OK) return DBRES_MISUSE;
-        if (table_add_to_context(data, algo, table_name) == false) return DBRES_MISUSE;
+        char schema[512];
+        schema[0] = '\0';
+        int schema_rc = dbutils_table_settings_get_value(data, table_name, "*", CLOUDSYNC_KEY_SCHEMA, schema, sizeof(schema));
+        if (schema_rc != DBRES_OK || schema[0] == '\0') {
+            char *current_schema = database_current_schema(data);
+            if (current_schema && current_schema[0] != '\0') {
+                strncpy(schema, current_schema, sizeof(schema) - 1);
+                schema[sizeof(schema) - 1] = '\0';
+                dbutils_table_settings_set_key_value(data, table_name, "*", CLOUDSYNC_KEY_SCHEMA, schema);
+            }
+            if (current_schema) cloudsync_memory_free(current_schema);
+        }
+
+        const char *table_ref = table_name;
+        char qualified[1024];
+        if (schema[0] != '\0') {
+            snprintf(qualified, sizeof(qualified), "%s.%s", schema, table_name);
+            table_ref = qualified;
+        }
+
+        if (database_create_triggers(data, table_ref, algo) != DBRES_OK) return DBRES_MISUSE;
+        if (table_add_to_context(data, algo, table_ref) == false) return DBRES_MISUSE;
 
         DEBUG_SETTINGS("load tbl_name: %s value: %s", key, value);
     }

src/dbutils.c

@@ -24,6 +24,7 @@
 #define CLOUDSYNC_KEY_SEND_SEQ              "send_seq"
 #define CLOUDSYNC_KEY_DEBUG                 "debug"
 #define CLOUDSYNC_KEY_ALGO                  "algo"
+#define CLOUDSYNC_KEY_SCHEMA                "schema"
 
 // settings
 int dbutils_settings_init (cloudsync_context *data);