Update HISTORY.md for forward compatibility

Summary: facebook#6060 broke forward compatiblity for releases from 3.10 to 4.2. Update HISTORY.md to mention it. Also remove it from the compatibility tests.

HISTORY.md

@@ -1,10 +1,7 @@
 # Rocksdb Change Log
 ## Unreleased
-### Bug Fixes
-* Fix data corruption casued by output of intra-L0 compaction on ingested file not being placed in correct order in L0.
-* Fix a data race between Version::GetColumnFamilyMetaData() and Compaction::MarkFilesBeingCompacted() for access to being_compacted (#6056). The current fix acquires the db mutex during Version::GetColumnFamilyMetaData(), which may cause regression.
-
 ### Public API Change
+* RocksDB release 4.1 or older will not be able to open DB generated by the new release. 4.2 was released on Feb 23, 2016.
 * TTL Compactions in Level compaction style now initiate successive cascading compactions on a key range so that it reaches the bottom level quickly on TTL expiry. `creation_time` table property for compaction output files is now set to the minimum of the creation times of all compaction inputs.
 * Changed the default value of periodic_compaction_seconds to `UINT64_MAX` which allows RocksDB to auto-tune periodic compaction scheduling. When using the default value, periodic compactions are now auto-enabled if a compaction filter is used. A value of `0` will turn off the feature completely.
 * With FIFO compaction style, options.periodic_compaction_seconds will have the same meaning as options.ttl. Whichever stricter will be used. With the default options.periodic_compaction_seconds value with options.ttl's default of 0, RocksDB will give a default of 30 days.
@@ -24,7 +21,9 @@
 * For 64-bit hashing, RocksDB is standardizing on a slightly modified preview version of XXH3. This function is now used for many non-persisted hashes, along with fastrange64() in place of the modulus operator, and some benchmarks show a slight improvement.
 
 ### Bug Fixes
-* Fix a assertion failure in MultiGe4t() when BlockBasedTableOptions::no_block_cache is true and there is no compressed block cache
+* Fix data corruption casued by output of intra-L0 compaction on ingested file not being placed in correct order in L0.
+* Fix a data race between Version::GetColumnFamilyMetaData() and Compaction::MarkFilesBeingCompacted() for access to being_compacted (#6056). The current fix acquires the db mutex during Version::GetColumnFamilyMetaData(), which may cause regression.
+* Fix a assertion failure in MultiGet() when BlockBasedTableOptions::no_block_cache is true and there is no compressed block cache
 * If a call to BackupEngine::PurgeOldBackups or BackupEngine::DeleteBackup suffered a crash, power failure, or I/O error, files could be left over from old backups that could only be purged with a call to GarbageCollect. Any call to PurgeOldBackups, DeleteBackup, or GarbageCollect should now suffice to purge such files.
 * Fix a buffer overrun problem in BlockBasedTable::MultiGet() when compression is enabled and no compressed block cache is configured.
 * Fix a bug in DBIter that is_blob_ state isn't updated when iterating backward using seek.

tools/check_format_compatible.sh

@@ -54,7 +54,7 @@ with open('${sorted_input_data}', 'w') as f:
 EOF
 
 declare -a backward_compatible_checkout_objs=("2.2.fb.branch" "2.3.fb.branch" "2.4.fb.branch" "2.5.fb.branch" "2.6.fb.branch" "2.7.fb.branch" "2.8.1.fb" "3.0.fb.branch" "3.1.fb" "3.2.fb" "3.3.fb" "3.4.fb" "3.5.fb" "3.6.fb" "3.7.fb" "3.8.fb" "3.9.fb")
-declare -a forward_compatible_checkout_objs=("3.10.fb" "3.11.fb" "3.12.fb" "3.13.fb" "4.0.fb" "4.1.fb" "4.2.fb" "4.3.fb" "4.4.fb" "4.5.fb" "4.6.fb" "4.7.fb" "4.8.fb" "4.9.fb" "4.10.fb" "4.11.fb" "4.12.fb" "4.13.fb" "5.0.fb" "5.1.fb" "5.2.fb" "5.3.fb" "5.4.fb" "5.5.fb" "5.6.fb" "5.7.fb" "5.8.fb" "5.9.fb" "5.10.fb")
+declare -a forward_compatible_checkout_objs=("4.2.fb" "4.3.fb" "4.4.fb" "4.5.fb" "4.6.fb" "4.7.fb" "4.8.fb" "4.9.fb" "4.10.fb" "4.11.fb" "4.12.fb" "4.13.fb" "5.0.fb" "5.1.fb" "5.2.fb" "5.3.fb" "5.4.fb" "5.5.fb" "5.6.fb" "5.7.fb" "5.8.fb" "5.9.fb" "5.10.fb")
 declare -a forward_compatible_with_options_checkout_objs=("5.11.fb" "5.12.fb" "5.13.fb" "5.14.fb" "5.15.fb" "5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb")
 declare -a checkout_objs=(${backward_compatible_checkout_objs[@]} ${forward_compatible_checkout_objs[@]} ${forward_compatible_with_options_checkout_objs[@]})
 declare -a extern_sst_ingestion_compatible_checkout_objs=("5.14.fb" "5.15.fb" "5.16.fb" "5.17.fb" "5.18.fb" "6.0.fb" "6.1.fb" "6.2.fb" "6.3.fb" "6.4.fb" "6.5.fb")