post-fixes for TRUNCATE

* fix the truncate-by-handler variant, used by InnoDB
* test that insert works after truncate, meaning graph table was emptied
* test that the vector index size is zero after truncate in MyISAM

mysql-test/main/vector,myisam.rdiff

+--- a/mysql-test/main/vector.result
++++ b/mysql-test/main/vector.result
+@@ -305,8 +305,30 @@
+ create table t1 (id int auto_increment primary key, v blob not null, vector index (v));
+ insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
+ truncate table t1;
++
++MyISAM file:         datadir/test/t1#i#01
++Record format:       Packed
++Character set:       ? (0)
++Data records:                    0  Deleted blocks:                 0
++Recordlength:                   30
++
++table description:
++Key Start Len Index   Type
++1   3     6   unique  varbin NULL          
++2   2     1   multip. int8                 
+ insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
+ truncate table t1;
++
++MyISAM file:         datadir/test/t1#i#01
++Record format:       Packed
++Character set:       ? (0)
++Data records:                    0  Deleted blocks:                 0
++Recordlength:                   30
++
++table description:
++Key Start Len Index   Type
++1   3     6   unique  varbin NULL          
++2   2     1   multip. int8                 
+ insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
+ select id, hex(v) from t1;
+ id	hex(v)

mysql-test/main/vector.result

@@ -303,11 +303,14 @@ id	hex(v)
 drop table t1, t2;
 db.opt
 create table t1 (id int auto_increment primary key, v blob not null, vector index (v));
+insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
 truncate table t1;
-insert t1 (v) values (x'e360d63ebe554f3fcdbc523f4522193f5236083d');
+insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
 truncate table t1;
-select * from t1;
-id	v
+insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
+select id, hex(v) from t1;
+id	hex(v)
+1	E360D63EBE554F3FCDBC523F4522193F5236083D
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
@@ -315,6 +318,6 @@ t1	CREATE TABLE `t1` (
   `v` blob NOT NULL,
   PRIMARY KEY (`id`),
   VECTOR KEY `v` (`v`)
-) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
+) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
 drop table t1;
 db.opt

mysql-test/main/vector.test

@@ -103,10 +103,20 @@ drop table t1, t2;
 list_files $datadir/test;
 
 create table t1 (id int auto_increment primary key, v blob not null, vector index (v));
+insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
 truncate table t1;
-insert t1 (v) values (x'e360d63ebe554f3fcdbc523f4522193f5236083d');
+if ($MTR_COMBINATION_MYISAM) {
+--replace_result $datadir datadir
+--exec $MYISAMCHK -d $datadir/test/t1#i#01
+}
+insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
 truncate table t1;
-select * from t1;
+if ($MTR_COMBINATION_MYISAM) {
+--replace_result $datadir datadir
+--exec $MYISAMCHK -d $datadir/test/t1#i#01
+}
+insert t1 (id, v) values (1, x'e360d63ebe554f3fcdbc523f4522193f5236083d');
+select id, hex(v) from t1;
 replace_result InnoDB MyISAM;
 show create table t1;
 drop table t1;

sql/handler.cc

@@ -5477,7 +5477,7 @@ handler::ha_delete_all_rows()
 
   int err= delete_all_rows();
   if (!err)
-    err= table->hlindexes_on_delete_all();
+    err= table->hlindexes_on_delete_all(false);
 
   return err;
 }
@@ -5496,7 +5496,14 @@ handler::ha_truncate()
               m_lock_type == F_WRLCK);
   mark_trx_read_write();
 
-  return truncate();
+  int err= truncate();
+  if (!err && table->s->total_keys > table->s->keys)
+  {
+    if (!(err= table->hlindex_open(table->s->keys)))
+      err= table->hlindexes_on_delete_all(true);
+  }
+
+  return err;
 }
 
 

sql/sql_base.cc

@@ -9945,11 +9945,11 @@ int TABLE::hlindexes_on_delete(const uchar *buf)
   return 0;
 }
 
-int TABLE::hlindexes_on_delete_all()
+int TABLE::hlindexes_on_delete_all(bool truncate)
 {
   DBUG_ASSERT(s->total_keys - s->keys == (hlindex != NULL));
   if (hlindex && hlindex->in_use)
-    if (int err= mhnsw_delete_all(this, key_info + s->keys))
+    if (int err= mhnsw_delete_all(this, key_info + s->keys, truncate))
       return err;
   return 0;
 }

sql/table.h

@@ -1798,7 +1798,7 @@ struct TABLE
   int hlindexes_on_insert();
   int hlindexes_on_update();
   int hlindexes_on_delete(const uchar *buf);
-  int hlindexes_on_delete_all();
+  int hlindexes_on_delete_all(bool truncate);
   int reset_hlindexes();
 
   void prepare_triggers_for_insert_stmt_or_event();

sql/vector_mhnsw.cc

@@ -1249,7 +1249,7 @@ int mhnsw_invalidate(TABLE *table, const uchar *rec, KEY *keyinfo)
   return 0;
 }
 
-int mhnsw_delete_all(TABLE *table, KEY *keyinfo)
+int mhnsw_delete_all(TABLE *table, KEY *keyinfo, bool truncate)
 {
   TABLE *graph= table->hlindex;
 
@@ -1258,7 +1258,8 @@ int mhnsw_delete_all(TABLE *table, KEY *keyinfo)
   DBUG_ASSERT(keyinfo->algorithm == HA_KEY_ALG_VECTOR);
   DBUG_ASSERT(keyinfo->usable_key_parts == 1);
 
-  if (int err= graph->file->ha_delete_all_rows())
+  if (int err= truncate ? graph->file->truncate()
+                        : graph->file->delete_all_rows())
    return err;
 
   MHNSW_Context *ctx;

sql/vector_mhnsw.h

@@ -25,7 +25,7 @@ const LEX_CSTRING mhnsw_hlindex_table_def(THD *thd, uint ref_length);
 int mhnsw_insert(TABLE *table, KEY *keyinfo);
 int mhnsw_first(TABLE *table, KEY *keyinfo, Item *dist, ulonglong limit);
 int mhnsw_invalidate(TABLE *table, const uchar *rec, KEY *keyinfo);
-int mhnsw_delete_all(TABLE *table, KEY *keyinfo);
+int mhnsw_delete_all(TABLE *table, KEY *keyinfo, bool truncate);
 int mhnsw_next(TABLE *table);
 void mhnsw_free(TABLE_SHARE *share);