Re-drive index/constraint creation for split tables on --resume

src/bin/pgcopydb/cli_clone_follow.c

@@ -773,6 +773,21 @@ cloneDB(CopyDataSpec *copySpecs)
 		return false;
 	}
 
+	/*
+	 * On --resume the per-run part/index election tables still hold the pids of
+	 * dead prior-run workers. Clear them now, single-threaded and before any
+	 * table-data worker is forked, so a fresh election among live workers
+	 * re-drives index/constraint creation for split (multi-part) tables.
+	 */
+	if (copySpecs->resume)
+	{
+		if (!copydb_resume_reset_part_election(copySpecs))
+		{
+			/* errors have already been logged */
+			return false;
+		}
+	}
+
 	/* now register in the catalogs the already known startTime */
 	if (!summary_start_timing(sourceDB, TIMING_SECTION_TOTAL))
 	{

src/bin/pgcopydb/copydb.h

@@ -413,6 +413,7 @@ bool copydb_prepare_sequence_specs(CopyDataSpec *specs, PGSQL *pgsql, bool reset
 
 /* copydb_schema.c */
 bool copydb_fetch_schema_and_prepare_specs(CopyDataSpec *specs);
+bool copydb_resume_reset_part_election(CopyDataSpec *specs);
 bool copydb_objectid_is_filtered_out(CopyDataSpec *specs,
 									 uint32_t catalogOid,
 									 uint32_t oid,

src/bin/pgcopydb/copydb_schema.c

@@ -179,6 +179,45 @@ copydb_fetch_schema_and_prepare_specs(CopyDataSpec *specs)
 }
 
 
+/*
+ * copydb_resume_reset_part_election clears the per-run "who finished last"
+ * election tables (s_table_parts_done, s_table_indexes_done) so that a
+ * --resume run holds a fresh election among live workers.
+ *
+ * These tables only ever store per-run election tokens (a tableoid and the
+ * getpid() of the worker that observed the last part/index as done); progress
+ * itself lives in the summary table (done_time_epoch). On resume the stored
+ * pids belong to dead prior-run processes, so no live worker matches and the
+ * index/constraint enqueue for a split (multi-part) table is never re-driven.
+ * Clearing the tokens loses no progress and re-enqueue is idempotent
+ * (IF NOT EXISTS / doneTime / foundConstraintOnTarget checks).
+ *
+ * Must run single-threaded before any COPY/table-data worker is forked, or the
+ * workers would race and wipe freshly-elected tokens.
+ */
+bool
+copydb_resume_reset_part_election(CopyDataSpec *specs)
+{
+	DatabaseCatalog *sourceDB = &(specs->catalogs.source);
+
+	log_notice("Resetting stale part/index election state for --resume");
+
+	if (!catalog_execute(sourceDB, "delete from s_table_parts_done"))
+	{
+		/* errors have already been logged */
+		return false;
+	}
+
+	if (!catalog_execute(sourceDB, "delete from s_table_indexes_done"))
+	{
+		/* errors have already been logged */
+		return false;
+	}
+
+	return true;
+}
+
+
 /*
  * copydb_fetch_source_catalog_setup initializes our local catalog cache and
  * checks the setup and cache state.