remove explain, Currently, the query plan is
    in the process of change and modification,
    and the consistency check of the query plan is not performed

    remove explain, Currently, the query plan is
    in the process of change and modification,
    and the consistency check of the query plan is not performed

    remove explain, Currently, the query plan is
    in the process of change and modification,
    and the consistency check of the query plan is not performed

    Test results for reference:
    https://blog.csdn.net/adofsauron/article/details/127228984?spm=1001.2014.3001.5501

    TODO: Q4 and Q21
    The case is an exists subquery
    because the Tianmu engine converts
    the syntax tree to an inner join
    on an association surface.
    For details, see
    https://blog.csdn.net/adofsauron/article/details/127228984?spm=1001.2014.3001.5501

fix(handler): fix the bug for create table #mysql50#q.q should return failure and actually return success (#487)
	[summary]
	1.When creating a table in the tianmu engine, add code to determine whether the table name is empty.
	2.Add issue corresponding to mtr test case.

[summary]
1 innodb(in 5.7) system variable "innodb_large_prefix" default value is ON, follow it;

- fix the wrong links
- update contributors

    Switches are added to support controlling whether multithreading is used to nested loops

    The reason for adding a parameter to control whether to enable multithreaded nested loop is that

    1. Provides parameters for fast execution of single-threaded versus multithreaded comparisons
    2. At present, the physical layer is placed in the second stage because
    the multi-threaded transformation of Nested loop has not been thoroughly carried out during the development period.
    The argument that controls turning on multithreading is also needed for easy code rollback

    TODO: There is no time to continue to optimize this parameter,
    later need to provide a configurable parameter to
    control whether to enable multithreading

fix(tianmu) Fix: The problem that the corresponding table is conditional but will still be executed (EvaluatePack_IsNoDelete)(#579)

 Cause of the problem
    The reason for this problem is that when (ParameterizedFilter:: UpdateMultiIndex()) starts,
    (desc. attr. vc ->GetVarMap()) There is a problem with the size judgment of size().
    It should be>=1, but it is written as>1. Each filter logic will go to (FilterDeletedByTable).

 Solution
    Modify the judgment condition to>=1

    The current version does not enable multithreaded aggregation optimization,
    Here's why:
    Currently, for multi-thread parallel,
    it is not completely carried out to the physical layer,
    for DPN and PACK data structure,
    because the underlying physical block processing for multi-thread from the data structure support is missing,
    when a multi-thread switch occurs,
    the data that has been read out is reset.
    More time is needed to support parallel read IO across multiple threads from the underlying data structures,
    which is not available in the current version,
    so we plan to start the second phase of the multi-thread read IO process completely.

[summary]
We should apply pr lable, not issue lable.
1. A-bug ---> PR-bug
2. PR-Docs ---> PR-docs

[summary]
1. fix typo on mergify `PR-Docs` ---> `PR-docs`

* docs(tianmu): Update the docs of the intro and architecture

* style(trouble&FAQ): Update the style

* docs(Contributor): Update the Contributor list

* fix(docs): fix the wrong link

The logic of this modification is as follows:

Descriptor object, MIUpdatingIterator object and DimensionVector are all newly defined objects this time. If you want iterators to work, you must have corresponding DimGroups. Because I didn't fully understand the usage of these classes, I used (dims. SetAll()) to set them, causing all DimGroups to converge.

The modification method is to use the corresponding virtual column to set DimGroups, so that the data volume is at most the data volume of the current table

* feat(mergify):add docs pr rule and change queue method rebase

* docs(README): fix urls (#522)

* docs(README): fix Chinese document urls (#522)

* syw test

* syw commit mtr/create_index.test

* syw commit dropdb mtr

* add mtr create

* add mtr create_table

* commit mtr select

* Submit the modified script

* add mtr insert

* delete select_tpch.test

test

* delete select_tpch.result

* add tianmu_insert_delayed
Co-authored-by: Nmergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

1. fix the wrong command
2. Fix style display error of TCP-H Test Report

* feat(tianmu) Add upgrade directory (#510)

* Optimize the structure of DPN to support memory alignment