Weekly update in TiDB

Last two weeks, we landed 62 PRs in the TiDB repositories.

Added

• Support the SyncLog Key-Value request option.
• Support the NotFillCache Key-Value request option.
• Support the combination SQL modes.

Removed

• Close the aggregation pushdown by default and remove the CBO switch.
• Remove some useless code.
• Remove the usage of TypeClass completely.

Fixed

• Change the like function to be case sensitive.
• Prepare to enforce errcheck, step 1.
• Make the prepare statement retry when the schema is out-dated.
• Revoke etcd on ctx.Done to prevent the situation that no owner entry left.
• Pre-calculate the lower and upper scalar.
• Add length limitation for index comment.
• Make insert with calculated value behave the same as MySQL.
• Drop invalid cached region.

Improved

• Turn on the analyze statement pushdown switch.
• Upgrade pd-client to fix a bug.
• Rewrite the unit test for Minus and Plus functions.
• The analyze statement uses NewSelectResult.
• Remove the usage of evalExprToXXX functions to improve performance.
• Change structured slow log to friendly JSON output.
• Refactor parser step 2: to be compatible with MySQL syntax.
• Refactor the SelectDAG function parameter.
• Speed up the add index operation.
• Optimize the SortExec executor.
• Split separated region for newly created table.
• Change the schema validator data structure to queue.
• Change the way of transferring the handle.
• Support more signatures pushdown.

Weekly update in TiSpark

Added

• Add the Configuration Framework

Fixed

• Fix invalid leader store ID cases
• Remove unused parameter for TiSpark context during the startup

Weekly update in TiKV

Last two weeks, We landed 39 PRs in the TiKV repositories.

Added

• Use expression in DAG.
• Namespace isolation: http interface and classifier.
• Report read statistics to PD.
• Pushdown sampling: implement histogram.
• Support ppc64le.
• Pushdown the analyze request.
• Support the must_sync flag for raft ready.
• Introduce Disconnected and LowSpace states for store.
• Add an API to compact a range for the specified column family.

Fixed

• Stop the thread pool on shutdown.
• Fix block send problem in grpc.
• Fix potential unreachable drop.
• Fix tablecodec.

Improved

• Select response of DAG don’t need row meta.
• Add drop message metrics.
• Debug: implement size.
• Debug: implement region information.
• Add slow log for applying.
• Update gRPC to 1.6.1.
• Check whether peers need to split after initialization.
• Refactor Key-Value for PD.
• Config: change all the names to kebab-case](https://github.com/pingcap/pd/pull/772).
• Flush the leader message as soon as possible.
• Return error instead of panic if an expression is illegal.
• Update etcd to v3.2.6 for PD.
• Synchronize data before applying snapshots.
• Update the client URLs continuously.
• Adjust the region heartbeat metrics.

New contributors

• Priya Seth