Bug#30108154 - SLOW STARTUP FOR MYSQL 8.0 WITH MANY TABLES DUE TO THE TABLESPACE FILES SCAN

Post-push fix: Fix test failures reported on ASAN and Windows

The test failed because the server could not find the space id because of the
corrupted header page.

Modified the code to fall back to the heavier method of finding the space id
by traversing all the pages in the tablespace.

RB# 23455
Reviewed by: Mayank Prasad ([email protected])

Author: Rahul Agarkar

storage/innobase/fil/fil0fil.cc

@@ -10671,37 +10671,46 @@ space_id_t Fil_system::get_tablespace_id(const std::string &filename) {
     return dict_sys_t::s_invalid_space_id;
   }
 
-  auto bytes_read = fread(buf.get(), page_size, MAX_PAGES_TO_READ, fp);
+  auto pages_read = fread(buf.get(), page_size, MAX_PAGES_TO_READ, fp);
+
+  DBUG_EXECUTE_IF("invalid_header", pages_read = 0;);
+
+  /* Find the space id from the pages read if enough pages could be read.
+  Fall back to the more heavier method of finding the space id from
+  Datafile::find_space_id() if pages cannot be read properly. */
+  if (pages_read >= MAX_PAGES_TO_READ) {
+    auto bytes_read = pages_read * page_size;
 
 #ifdef POSIX_FADV_DONTNEED
-  posix_fadvise(fileno(fp), 0, bytes_read, POSIX_FADV_DONTNEED);
+    posix_fadvise(fileno(fp), 0, bytes_read, POSIX_FADV_DONTNEED);
 #endif /* POSIX_FADV_DONTNEED */
 
-  for (page_no_t i = 0; i < MAX_PAGES_TO_READ; ++i) {
-    const auto off = i * page_size + FIL_PAGE_SPACE_ID;
+    for (page_no_t i = 0; i < MAX_PAGES_TO_READ; ++i) {
+      const auto off = i * page_size + FIL_PAGE_SPACE_ID;
 
-    if (off == FIL_PAGE_SPACE_ID) {
-      /* Find out the page size of the tablespace from the first page.
-      In case of compressed pages, the subsequent pages can be of different
-      sizes. If MAX_PAGES_TO_READ is changed to a different value, then the
-      page size of subsequent pages is needed to find out the offset for
-      space ID. */
+      if (off == FIL_PAGE_SPACE_ID) {
+        /* Find out the page size of the tablespace from the first page.
+        In case of compressed pages, the subsequent pages can be of different
+        sizes. If MAX_PAGES_TO_READ is changed to a different value, then the
+        page size of subsequent pages is needed to find out the offset for
+        space ID. */
 
-      auto space_flags_offset = FSP_HEADER_OFFSET + FSP_SPACE_FLAGS;
+        auto space_flags_offset = FSP_HEADER_OFFSET + FSP_SPACE_FLAGS;
 
-      ut_a(space_flags_offset + 4 < n_bytes);
+        ut_a(space_flags_offset + 4 < n_bytes);
 
-      const auto flags = mach_read_from_4(buf.get() + space_flags_offset);
+        const auto flags = mach_read_from_4(buf.get() + space_flags_offset);
 
-      page_size_t space_page_size(flags);
+        page_size_t space_page_size(flags);
 
-      page_size = space_page_size.physical();
-    }
+        page_size = space_page_size.physical();
+      }
 
-    space_ids.push_back(mach_read_from_4(buf.get() + off));
+      space_ids.push_back(mach_read_from_4(buf.get() + off));
 
-    if ((i + 1) * page_size >= bytes_read) {
-      break;
+      if ((i + 1) * page_size >= bytes_read) {
+        break;
+      }
     }
   }
 
@@ -10725,11 +10734,9 @@ space_id_t Fil_system::get_tablespace_id(const std::string &filename) {
 
   /* Try the more heavy duty method, as a last resort. */
   if (space_id == UINT32_UNDEFINED) {
-    /* The ifstream will work for all file formats compressed or
-    otherwise because the header of the page is not compressed.
-    Where it will fail is if the first page is corrupt. Then for
-    compressed tablespaces we don't know where the page boundary
-    starts because we don't know the page size. */
+    /* If the first page cannot be read properly, then for compressed
+    tablespaces we don't know where the page boundary starts because
+    we don't know the page size. */
 
     Datafile file;
 
@@ -10740,8 +10747,8 @@ space_id_t Fil_system::get_tablespace_id(const std::string &filename) {
     ut_a(file.is_open());
     ut_a(err == DB_SUCCESS);
 
-    /* Read and validate the first page of the tablespace.
-    Assign a tablespace name based on the tablespace type. */
+    /* Use the heavier Datafile::find_space_id() method to
+    find the space id. */
     err = file.find_space_id();
 
     if (err == DB_SUCCESS) {