…ingcap#8044)

* ddl, executor: fix the issue of executing DDL after executing SQL failure in txn

bugfix fixed pingcap#7518

expression: MySQL compatible current_user function (pingcap#7801)

plan: propagate constant over outer join (pingcap#7794)

- extract `outerCol = const` from join conditions and filter conditions,
  substitute `outerCol` in join conditions with `const`;
- extract `outerCol = innerCol` from join conditions, derive new join
  conditions based on this column equal condition and `outerCol` related
  expressions in join conditions and filter conditions;

util/timeutil: fix data race caused by forgetting set stats lease to 0 (pingcap#7901)

stats: handle ddl event for partition table (pingcap#7903)

plan: implement Operand and Pattern of cascades planner. (pingcap#7910)

planner: not convert to TableDual if empty range is derived from deferred constants (pingcap#7808)

plan: move projEliminate behind aggEliminate (pingcap#7909)

admin: fix admin check table bug of byte compare (pingcap#7887)

* admin: remove reflect deepEqual

stats: fix panic caused by empty histogram (pingcap#7912)

plan: fix panic caused by empty schema of LogicalTableDual (pingcap#7906)

* fix drop view if exist error (pingcap#7833)

executor: refine `explain analyze` (pingcap#7888)

executor: add an variable to compatible with MySQL insert for OGG (pingcap#7863)

expression: maintain `DeferredExpr` in aggressive constant folding. (pingcap#7915)

stats: fix histogram boundaries overflow error (pingcap#7883)

ddl:support the definition of `null` change to `not null` using `alter table` (pingcap#7771)

* ddl:support the definition of null change to not null using alter table

ddl: add check when create table with foreign key. (pingcap#7885)

* ddl: add check when create table with foreign key

planner: eliminate if null on non null column (pingcap#7924)

executor: fix a bug in point get (pingcap#7934)

planner, executor: refine ColumnPrune for LogicalUnionAll (pingcap#7930)

executor: fix panic when limit is too large (pingcap#7936)

ddl: add TiDB version to metrics (pingcap#7902)

stats: limit the length of sample values (pingcap#7931)

vendor: update tipb (pingcap#7893)

planner: support the Group and GroupExpr for the cascades planner (pingcap#7917)

store/tikv: log more information when other err occurs (pingcap#7948)

types: fix date time parse (pingcap#7933)

ddl: just print error message when ddl job is normal to calcel, to eliminate noisy log (pingcap#7875)

stats: update delta info for partition table (pingcap#7947)

explaintest: add explain test for partition pruning (pingcap#7505)

util: move disjoint set to util package (pingcap#7950)

util: add PreAlloc4Row and Insert for Chunk and List (pingcap#7916)

executor: add the slow log for commit (pingcap#7951)

expression: add builtin json_keys (pingcap#7776)

privilege: add USAGE in `show grants` for mysql compatibility (pingcap#7955)

ddl: fix invailid ddl job panic (pingcap#7940)

*: move ast.NewValueExpr to standalone parser_driver package (pingcap#7952)

Make the ast package get rid of the dependency of types.Datum

server: allow cors http request (pingcap#7939)

*: move `Statement` and `RecordSet` from ast to sqlexec package (pingcap#7970)

pr suggestion update

executor/aggfuncs: split unit tests to corresponding file (pingcap#7993)

store/tikv: fix typo (pingcap#7990)

executor, planner: clone proj schema for different children in buildProj4Union (pingcap#7999)

executor: let information_schema be the first database in ShowDatabases (pingcap#7938)

stats: use local feedback for partition table (pingcap#7963)

executor: add unit test for aggfuncs (pingcap#7966)

server: add log for binary execute statement (pingcap#7987)

admin: refine admin check decoder (pingcap#7862)

executor: improve wide table insert & update performance (pingcap#7935)

ddl: fix reassigned partition id in `truncate table` does not take effect (pingcap#7919)

fix reassigned partition id in truncate table does not take effect

add changelog for 2.1.0 rc4 (pingcap#8020)

*: make parser package dependency as small as possible (pingcap#7989)

parser: support `:=` in the `set` syntax (pingcap#8018)

According to MySQL document, `set` use the = assignment operator,
but the := assignment operator is also permitted

stats: garbage collect stats for partition table (pingcap#7962)

docs: add the proposal for the column pool (pingcap#7988)

expression: refine built-in func truncate to support uint arg (pingcap#8000)

stats: support show stats for partition table (pingcap#8023)

stats: update error rate for partition table (pingcap#8022)

stats: fix estimation for out of range point queries (pingcap#8015)

*: move parser to a separate repository (pingcap#8036)

executor: fix wrong result when index join on union scan. (pingcap#8031)

Do not modify Plan of dataReaderBuilder directly, because it would
impact next batch of outer rows, as well as other concurrent inner
workers. Instead, build a local child builder to store the child plan.

planner: fix a panic of a cached prepared statement with IndexScan (pingcap#8017)

*: fix the issue of executing DDL after executing SQL failure in txn (pingcap#8044)

* ddl, executor: fix the issue of executing DDL after executing SQL failure in txn

add unit test

remove debug info

add like evaluator case sensitive test

ddl, domain: make schema correct after canceling jobs (pingcap#7997)

unit test fix

code format

proposal: maintaining histograms in plan. (pingcap#7605)

support _tidb_rowid for table scan range (pingcap#8047)

var rename fix