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  1. MariaDB Server
  2. MDEV-32238

Add a switch to disable spider group by handler

Details

    Description

      This serves as a workaround for many bugs caused by the spider group
      by handler (GBH) (labeled with spider-gbh). There is a system
      variable spider_use_handler that could disable the group by
      handler if it is set to 1*, but it was deprecated, and then deleted
      in 10.10+ (MDEV-27256). So we could add
      spider_disable_group_by_handler to 10.10+.

      For context, see a comment in MDEV-26247[1]:

      Here's a little demo showing disabling the spider GBH "fixes" the
      issue. It could be a fallback / workaround, and it would be
      interesting to see which other gbh bugs can also be mitigated by
      this workaround.

      637c1a3c315 upstream/bb-11.0-ycp-mdev-26247-disable-gbh MDEV-26247 [demo] disabling the spider gbh fixes the issue

      update on [2023-09-22 Fri]: I confirm that all other bugs current
      labeled with spider-gbh can be mitigated by this workaround:

      So it makes sense to add a system variable e.g.
      spider_disable_group_by_handler.

      [1] https://jira.mariadb.org/browse/MDEV-26247?focusedCommentId=269982&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-269982

      *: When spider_use_handler is set to 1, it skips creating
      conn_holder on spider fields which causes the return of a NULL
      pointer in spider_create_group_by_hander().

      Attachments

        Issue Links

          duplicates

          Task - A task that needs to be done. MDEV-26364 Add Spider server variable for disabling GROUP BY handler

          • Major - Major loss of function.
          • Closed
          relates to

          Task - A task that needs to be done. MDEV-32246 Add tests to spider-gbh tickets for 10.4-6 with the spider_use_handler workaround

          • Critical - Crashes, loss of data, severe memory leak.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. MDEV-26247 Spider: Valid LEFT JOIN results in ERROR 1064

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-28998 ASAN errors in spider_fields::free_conn_holder or spider_create_group_by_handler

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-29163 Server crash with SIGSEGV or dynamic-stack-buffer-overflow in spider_db_mbase_util::append_table

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-30392 Syntax error upon query with subquery from Spider table

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-31645 Spider doesn't recognize semi JOIN

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-33197 SIGSEGV and UBSAN member access [within/on] null pointer in spider_db_get_row_from_tmp_tbl, Assertion in spider_db_errorno and SIGSEGV in spider_db_store_result

          • Major - Major loss of function.
          • Confirmed

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              ycp Yuchen Pei
              ycp Yuchen Pei
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              Dates

                Created:
                Updated:
                Resolved:

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